The magnetism of magnetic material reachs project application

Oe, with millionfold watch it is MGOe 〕 . Exquisite Hc, Br reachs permanent and magnetic material (BH) M has healed greatly more, especially (BH) M, the energy of interiorly of keep in storage of the place after it is magnetized on behalf of this magnet, (BH) M value represents it to be able to do work external more greatly more, resemble never dried up batteries is same, if Hc is quite big (above of thousands of Oe) , courier temperature is quite high, it not easy by disappear (retreat) magnetism. 200Oe of ＞ of the Hc on the project person, can call permanent magnet. 19 centuries end comes at the beginning of 20 centuries, practicable is permanent magnet quenchs only carbolic steel. Carbolic steel quenchs sclerotic, hc lifts namely, more hard person Hc heals tall, permanent magnetism weighs reason again " hard " magnetic; Conversely anneal bate person present temporary magnetism, or " soft " magnetic. Quench steel Hc has 50 ～ 70Oe only, (BH) M has 0 only.

2 ～ 0.

3MGOe. 1916, the scientist adds Cr, W, Co inside carbolic steel, make Hc is added to 145 ～ 250Oe, (BH) M is close at 1MGOe, at that time it is very big breakthrough. 3 islands invented day person 1931 Fe-Ni-Al3 yuan alloy magnet, hc is as high as 500Oe (BH) M is amounted to 1.

4MGOe, open the entrance door that latter-day magnetically hard material develops. Give priority to with Fe-Al-Ni, add the Alnico alloy that the element such as Co, Cu, Si, Ti is improved and becomes, till the mainstream that permanent magnet is all the time before 1970. The rule that Jie alloy devises material scientist, control its to change, make generation leaves decompose reaction (Spinodaldecomposition) ; Cooling inside magnetic field, the way of photograph edge magnetic field that makes disclose earnings grows and get the outstanding magnet with different square very tall sex, hc amounts to 600 ～ 2000Oe, (BH) M is 3 ～ 12MGOe, what Jie alloy constitutes cent and heat treatment and can adjust magnetic data is characteristic. At this late hour, although update the permanent magnetism of type or valence cheap to already replaced gradually in great quantities, but its very stable magnetism (applicable comes the high temperature of 500 ℃ , make it is in certain and specific application (like microwave communication) on, fall into disuse not easily still. The alloy of Fe-Cr-Co permanent magnetism of acting 1970 invention uses the principle of Alnico to be designed namely, its magnetism also comparatives with Alnico alloy, the author ever had made old research, graph 3 show namely use magnetic field heat treatment, make of Fe28Cr-12Co-Ti alloy from the case that resolves direction of edge magnetic field to arrange. Decompose the grain that come out average diameter makes an appointment with 300Å , average length makes an appointment with 1200Å , the motion that magnetism area wall is inside its is extremely difficult, reason Hc cost is very high, become permanent magnet. 1932 ～ between 1938, the magnetic oxide that in day, carry on one's shoulder two ground begin to develop -- ferrite (Ferrites) , for one of mainstreams of permanent now magnetic material. The bases of ferrite is Ba0.

6Fe2O3 reachs Sr0.

6Fe2O3, belonging to Wu Liufang brilliant is; Its Hc is made an appointment with 1.

8 ～ 3.

2kOe, br is made an appointment with 2.

2 ～ 4.

3, (BH) M is made an appointment with 1.

0 ～ 4.

0MGOe (inspect additive to reach install Cheng to wait and different) . By at valence cheap, make it is easy to take, application is very wide, at present Taiwan month needs 2, more than tons 000, about 3 ／ 4 self-restrained. 1969, rare earth of success of material scientist development - the permanent magnet that cobalt changes thing, for permanent magnet open up another new scope of operation. Come nearly 20 years, permanent magnet has rare land great progress. From the earliest SmCo5 alloy Sm(Co, fe, cu, zr)7.

2-8.

5 (namely Sm2CO17) alloy, the Nd2Fe14B alloy to recently (rose 1984) , magnetism can accumulate the 20MGOe from record-breaking (SmCo5) to 30MGOe (Sm2Co17) arrive again 50MGOe (Nd-Fe-B alloy) , present the progress of saltant type, this is the research of science of Gui Gongwu material and development. Home is in at present the research of this respect and development work are as synchronous as international already, industry is produced also spread out, for very potential high-tech industry. Graph the tall solution of the 4 Nd-Fe-B alloy that study for author place resembles electron microscope picture, show the bead bound between two Nd2Fe14B grain has cubic metre of heart of a body (Bcc) the construction of the photograph, the parallel strain line inside grain is the grid of C plane to resemble. Other magnetically hard material still have a lot of, for example Cu-Ni-Co alloy, Mn-Al-C alloy and Pt-Co alloy, still do not have below more than 10 kinds, be restricted to cannot introduce one by one at length. In permanent and magnetic material, having a few is volume is very minor and effect is very big " magnetism record material " (Magneticrecordingmaterial) : Farinose has γ - Fe2O3, CrO2, Fe4N, metallic pink is like alloyed powder of Fe pink, Fe-Co to wait, use the Wu Luyin belt, kinescope belt, industry such as diskette in great quantities; Additionally the Fe-Ni that makes filmy record, Fe-Ni-P, Fe-Ni-Cr, Fe-Ni-Co waits with at strong pattern diskette, co-Cr uses Wu Chuizhi record, tb-Fe-Co reachs Gd-Co to wait to read written magnetism smooth record to wait with Wu Ke. The place before magnetically hard material is like is narrated is device of one energy storage, should design only proper, it can do work, afore-mentioned " record " it is namely. Other applied circumstances include: Horn, motor, dynamo, plan implement, suck write the too numerous to mention one by one such as machine of device, magnetic separation. Temporarily magnetic material reachs his to use temporarily magnetic data is to be in be magnetized (when the coil that is circled outside its for example connects electrify to flow) hind present very strong magnetism, magnetizing field moves after dividing, the material of the degauss on the horse. Accordingly, can use on alternating current machine, even the applied circumstance of Wu Gaopin and UHF. Its use the requirement that go up is to guide magnetism rate and Bs value heal Gao Yujia, hc value heals low more beautiful (accordingly B × H is worth -- delegate magnetism caustic, more small) . For the course with development, temporarily magnetic material (namely soft magnetism material) earlier than magnetically hard material, and achievement relatively plentiful and substantial. For example pure iron itself is namely very the soft magnetism material of beautiful, begin to use namely from 19 centuries end, current dosage is very big still. Alloy of acting 1910 Fe-Ni already came out by invention of lab of American shellfish Er namely, call later guide high magnetism alloy (Permalloy) ; Take the place of to 1950 0 values of its μ (see a picture 2) already can be as high as 100, 000, call superconductive magnetism alloy (Supermalloy) . The effect that its magnetism suffers nickel content, make friends to extend to anneal means to wait is very big. Silicon steel piece initiate at 1900 around, come to made silicon steel of set prescription tropism 1930 piece since, it already became electric machinery to use the main trend of soft magnetism alloy. Because these soft alloy fasten conductor, suit the occasion that uses at low frequency only mostly. Material of ferrite soft magnetism is given priority to with department of pointed spar brilliant; General pattern is MFe2O4, m is diatomic ion, be like Mn++ , Zn++ , Ni++ , Cu++ , Mg++ , Co++ , wait at Fe++ even, for example at present the commonnest on market (Mn, zn)Fe2O4, (Ni, zn) .

Fe2O4 and (Mn, mg)Fe2O4. Because of ferrite soft magnetism material fastens oxide, resistance is great, applicable Wu Gaopin (the circumstance under 100MHz. If ultrahigh frequency, be like 100MHz ～ 500GHz (microwave limits) needing Zhe Liu stone is iron oxygen magnet -- Y3Fe5O12 and its ramification. 1958, dewey is neat (Duwez) invention noncrystalline alloy (Amorphousalloy) since device, 〔 of the alloy that be not brilliant calls metallic glass again (Metallicglass) the magnetism of 〕 and mechanical sex special suffer take seriously, and at 1970 ～ upsurge of very big a research is formed between 1980. American Allied company at 1974, begin to roll out commercial to be not brilliant small band, its Bs is as high as 16kG, hc is dinky (0.

01Oe is the following) , resistor relatively silicon steel piece tall, because this uses it to make transformer, magnetism caustic is far low at silicon steel piece person, for most the below one for generations that is valued is soft magnetic material. Weak magnetic data applies extensively at following each respect: One communication respect -- club of inductor, filter, antenna. Respect of 2 electric power -- transformer, motor, dynamo, block flows implement etc. Side of product of 3 consumption sex -- television deflection yoke and gallop return circle of streamline of transformer, block to wait. Respect of 4 magnetic head -- recording uses magnetic head (guide high magnetism alloy) , kinescope uses magnetic head (Fe-Si-Al alloy) , computer uses magnetic head (Mn-Zn ferrite) etc. 5 other utility are obstructed like magnetism implement, magnetic core of magnetism amplifier, switch and advanced electro-magnet. Magnetic material is the material that more than 1 appearance turn covers a metal to reach metalloid (pottery and porcelain) , bead of filmy, pink reachs a makings; Its application range is wide reach appliance of mechanical, electric machinery, electron, information, traffic, family expenses; The foundation that its study depend on reachs material project at science of solid-state physics, material. Accordingly, magnetic material is one kind " attraction is very strong " material, it is in " compatible and harbour " in fast thrive. The magnetic data industry of our country already had history of nearly 20 years, magnetic data research is only more than 10 years of histories, although small also have result, but as advanced as industry country is compared, still lag behind very far, need government, business circles and academia many sided cooperate, throw manpower, financial capacity, in order to promote the technology of magnetic material administrative levels. By at it the technology that is diversification, its promote the progress that also can drive other and relevant technology. The attention of our neighbour Japan to magnetic material, advocate with investment, can borrows lens for ours. Reference material 1.

B.

D.

Cullity, introductiontoMagneticMaterials, addison-WesleyPub.

Co.

, 1972.

2.

" magnetic material " data of technology of institute of data of technology academy industry Jin Chongxun taught 1987 project of science of material of Wu Qinghua university is answerer: Enchanter of Babi20boy- learn on job 3 class 3-219:25 [summary] magnetic material points to the stuff that has strong magnetism and project application value. Can divide in the main for: " permanent and magnetic material " , " temporarily magnetic material " reach " half permanent and magnetic material " 3 kinds big. They apply widely go up at the industry such as electron, electric machinery, information, machinery and traffic. The character of the origin of magnetism of article brief introduction, of all kinds magnetic material and function. Magnetic material (Magneticmaterials) fasten our week to meet with the material of can be found everywhere. Markedder, be like white board disk of the magnet below the magnet that go up, magnetic Chinese checkers, compass, tape, magnetic head, gentle style is waited a moment; Have additionally manier package the magnetic data in face of certain device Xuan , if motor, television, transformer, car waits interior a moment, by no means an isolated case. Can say, magnetic material already the life be closely bound up with modern. Inside the domain of material science, its classify is in " electronic material " Xuan face (wait with conductor, dielectric, semiconductor paratactic) . But the stuff that has magnetism covers material of metallic stuff, pottery and porcelain again, even at high polymer material. Its configuration still includes a material (B1uk) , powdery body (Particulate) reach film (Thinfilm) etc. Because this is magnetic,material itself is the stuff that has diversity part. For the viewpoint with physics, any material are magnetic material, that is to say, material of avery kind of has certain magnetism appearance. Some will be quits inside magnetic field intensity of one fraction magnetic field, appear " diamagnetic " (Diamagnetism) , be like copper; Some has inside magnetic field tiny induction, appear " paramagnetic " (Paramagnetism) , be like air; Some produces very strong magnetic amount in induction of the meeting inside magnetic field -- call magnetization to measure (Magnetization) , present ferromagnetism (Ferromagnetism, weigh ferromagnetic again) or ferrimagnetism (Ferrimagnetism, say again inferior ferromagnetic) etc phyletic and various. On industry, provide ferromagnetic only or inferior the material ability of ferromagnetic tries to use. But go up in physics, chemistry and medicine, the magnetism of other type also has very big use. The most interesting example is, the magnetism resonance of element of human body organ is used on medicine, can make systemic checkup quickly, by organic element " magnetic " , can detect of pathological changes have without, uses device is called MRI (Magneticresonanceimaging) . Here, plan to introduce the ferromagnetic Ji Yajiang with industrial application greater value only magnetic material (permanent reach temporarily magnetic material; Half permanent person sort and application are less, be restricted not to talk at length) . Magnetic origin till 20 centuries previously, people (include a scientist) magnetic to material understanding, won't be in than our ancestor hundreds, even the understanding before Wu Shu chiliad is good go to that Xuan . Come more than 70 years recently, the physical home that relies on to write a lot of sufferring to cross close science to train, chemist and mathematician try hard ceaselessly, eventually can gradually unlock its mysterious veil, peep its panorama. Before letting our abide write virtuous the origin that the course will come to understand magnetism. Be informed by the experiment, have between two magnetic pole be sucked or exclusive power, call magnetic force. Accordingly by force measure, can be informed " magnetism " size. Strong can have moment of force, because the moment of force since magnetism place is called " magnetic moment " (Magneticmoment) . Inchoate scientist (for example the person such as Faraday, Courier) the size that tries to measure corporeal place to contain magnetic moment inside magnetic field and the relation that its change along with temperature, discover the different reaction of different material thereby. The amount that one object place contains magnetic moment is called " magnetization is measured " . The magnetization amount that unit magnetic field can cause is called " magnetic susceptibility " (Magneticsusceptibility) , concern to the ration of temperature by magnetic susceptibility, we to be able to be defined diamagnetic, paramagnetic those who reach ferromagnetic to wait is different. But why such? Still do not have the answer. Above all, is magnetic moment assorted Zuo ? If break up magnet again and again, the grain that every get anew all is one new magnet, have south, north (N, S) extremely, break up the smallest and still can retain N, S is polar it is magnetic moment namely. Current, we are foregone electronic spin or revolution, cause this to plant most subsection (be just like electric current to circle coil flow to create magnetic field) . In other words, magnetic moment is electronic motion (revolution, rotation) , the net amount that was not offsetted, i.e. is magnetism Tuo (Magneticspin) net value. Remove diamagnetic material beyond, all and other material has inside magnetic field more or less magnetic moment, measure OK and mensurably, they contain very apparent ground magnetic is atomic (element) . Is that Zuo ferromagnetic how Zuo comes? Why contain magnetic atom likewise and have a plenty of ferromagnetic, is some done not have however? 1907, wei Si (Weiss) repeat house grain at the experiment 1895, cooperate mathematician blue ancient prose again (Langeuim) academic, hypothesis is magnetic " element " (think the element is material at that time most subsection) have interaction, call molecular field (Molecularfield) , bold conclude the molecular field that is not ferromagnetic material is very small, and the molecular field of ferromagnetic material is very big, make to enough greatly " element " magnetic moment is the same as to arrange and amount to saturation. Temperature nods high to Courier (make up note: Ferromagnetism material turns into by ferromagnetic paramagnetic the temperature when, call Courier to nod) when above, the permutation that heat energy destroyed molecular field action, make magnetic " element " confused, it is namely paramagnetic. In that case, why won't the ferromagnetic element such as major iron, cobaltic, nickel attract other iron, cobaltic, nickel? Since their interior already magnetized saturation, should can regarding very strong permanent magnet as ability is. Wei Si puts forward another bold hypothesis again, that is content department to reduce freedom can in order to amount to stable change, can raise chaos to spend. Ferromagnetic material interior is divided automatically into a lot of zonule, call magnetism area (Magneticdomain) . Direction is being magnetized inside same magnetism area is consistent, the magnetization way of different magnetism interval is different and show a disorder to change, reason each other is quits, common sense does not have magnetism to it, try to magnetize inside magnetic field only, break the troubled waters of magnetism area, ability experiences its ferromagnetic. The experiment of later generations (1931) confirm this one " fatidical " (see a picture one) , make Wei Si name hangs down through the ages, its beg the principle that the manner of pursue one's studies of card is humanness take delight in talking about more bold hypothesis, carefully. 1948, wei Si's pupil Neal (N é El) continue his research, discover magnetic moment of certain material atomic gets crystallization check the impact is very big, and the action of molecular field is very strong, for what lose, the magnetization way that brings about photograph adjacent atom to list is opposite. If size is equal completely quits, appear " turn over ferromagnetic " (Antiferromagnetism) . If size differs, appear " inferior ferromagnetic " ; So far, of material " magnetism " phenomenal principle already was announced roughly, er is in the Buddhist nun to had the honor to win Nobel physics award 1970 consequently. The magnetism phenomenon of magnetic material by magnetism the growth and decline of the area is decided. The interface between magnetism area and magnetism area calls magnetism area wall (Domainwall) , tuo of the magnetism inside its turns to another direction gradually by a direction, it is very thin, have tens of coming only hundreds dust (Å ) . If the magnetism area wall of magnetic material can follow adscititious magnetic field change and move at any time, this material is very easy namely saturation be goinged to by magnetization, very easy also degauss; Conversely, if try the motion of wall of area of block up magnetism, be gone to by magnetization after saturation this material not easy by degauss. Former present temporary magnetism, latter presents permanent magnetism. The job that magnetic material learns the home is in namely at: Use metallurgy of engineering of solid-state physics, material, physics, mechanical metallurgy to wait learn manage or skill, the part that controls magnetic material, microstructure and make its property closes to need at place. Permanent and magnetic material and the actor bad that its use magnetic data constant with magnetic hysteresis curve (Hysteresisloop, see a picture 2) , of the data presentation that presents. Watch of the OBs on the graph magnetizes a curve, call at the tangent slope of origin on its guide magnetism is led first (Initialpermeability, µo) , secant slope representing's specific B ／ H (intensity of magnetic field of magnetic induction ／ ) ratio, the biggest person it is namely the biggest guide magnetism is led (µm) . Bs dot represents saturated magnetic induction (Saturationinduction) unit with 1000 gauss (KG) express; Br dot is rudimental magnetic induction; Hc dot is called protect magnetic force or Coerciveforce of 〔 of force of correct magnetic retentivity, the unit is Oe or KOe, 1Oe comparatives at (4 π of 1000 ／ ) 〕 of A ／ M. Allow to represented one specific B × H to be worth on the 2nd quadrantal magnetic hysteresis curve (place of umbriferous to B, H line surrounds an area) , its are the biggest person call the biggest magnetism to be able to accumulate 〔 Maximumenergyproduct, logogram is (BH) M, unit G.

Oe, with millionfold watch it is MGOe 〕 . Exquisite Hc, Br reachs permanent and magnetic material (BH) M has healed greatly more, especially (BH) M, the energy of interiorly of keep in storage of the place after it is magnetized on behalf of this magnet, (BH) M value represents it to be able to do work external more greatly more, resemble never dried up batteries is same, if Hc is quite big (above of thousands of Oe) , courier temperature is quite high, it not easy by disappear (retreat) magnetism. 200Oe of ＞ of the Hc on the project person, can call permanent magnet. 19 centuries end comes at the beginning of 20 centuries, practicable is permanent magnet quenchs only carbolic steel. Carbolic steel quenchs sclerotic, hc lifts namely, more hard person Hc heals tall, permanent magnetism weighs reason again " hard " magnetic; Conversely anneal bate person present temporary magnetism, or " soft " magnetic. Quench steel Hc has 50 ～ 70Oe only, (BH) M has 0 only.

2 ～ 0.

3MGOe. 1916, the scientist adds Cr, W, Co inside carbolic steel, make Hc is added to 145 ～ 250Oe, (BH) M is close at 1MGOe, at that time it is very big breakthrough. 3 islands invented day person 1931 Fe-Ni-Al3 yuan alloy magnet, hc is as high as 500Oe (BH) M is amounted to 1.

4MGOe, open the entrance door that latter-day magnetically hard material develops. Give priority to with Fe-Al-Ni, add the Alnico alloy that the element such as Co, Cu, Si, Ti is improved and becomes, till the mainstream that permanent magnet is all the time before 1970. The rule that Jie alloy devises material scientist, control its to change, make generation leaves decompose reaction (Spinodaldecomposition) ; Cooling inside magnetic field, the way of photograph edge magnetic field that makes disclose earnings grows and get the outstanding magnet with different square very tall sex, hc amounts to 600 ～ 2000Oe, (BH) M is 3 ～ 12MGOe, what Jie alloy constitutes cent and heat treatment and can adjust magnetic data is characteristic. At this late hour, although update the permanent magnetism of type or valence cheap to already replaced gradually in great quantities, but its very stable magnetism (applicable comes the high temperature of 500 ℃ , make it is in certain and specific application (like microwave communication) on, fall into disuse not easily still. The alloy of Fe-Cr-Co permanent magnetism of acting 1970 invention uses the principle of Alnico to be designed namely, its magnetism also comparatives with Alnico alloy, the author ever had made old research, graph 3 show namely use magnetic field heat treatment, make of Fe28Cr-12Co-Ti alloy from the case that resolves direction of edge magnetic field to arrange. Decompose the grain that come out average diameter makes an appointment with 300Å , average length makes an appointment with 1200Å , the motion that magnetism area wall is inside its is extremely difficult, reason Hc cost is very high, become permanent magnet. 1932 ～ between 1938, the magnetic oxide that in day, carry on one's shoulder two ground begin to develop -- ferrite (Ferrites) , for one of mainstreams of permanent now magnetic material. The bases of ferrite is Ba0.

6Fe2O3 reachs Sr0.

6Fe2O3, belonging to Wu Liufang brilliant is; Its Hc is made an appointment with 1.

8 ～ 3.

2kOe, br is made an appointment with 2.

2 ～ 4.

3, (BH) M is made an appointment with 1.

0 ～ 4.

0MGOe (inspect additive to reach install Cheng to wait and different) . By at valence cheap, make it is easy to take, application is very wide, at present Taiwan month needs 2, more than tons 000, about 3 ／ 4 self-restrained. 1969, rare earth of success of material scientist development - the permanent magnet that cobalt changes thing, for permanent magnet open up another new scope of operation. Come nearly 20 years, permanent magnet has rare land great progress. From the earliest SmCo5 alloy Sm(Co, fe, cu, zr)7.

2-8.

5 (namely Sm2CO17) alloy, the Nd2Fe14B alloy to recently (rose 1984) , magnetism can accumulate the 20MGOe from record-breaking (SmCo5) to 30MGOe (Sm2Co17) arrive again 50MGOe (Nd-Fe-B alloy) , present the progress of saltant type, this is the research of science of Gui Gongwu material and development. Home is in at present the research of this respect and development work are as synchronous as international already, industry is produced also spread out, for very potential high-tech industry. Graph the tall solution of the 4 Nd-Fe-B alloy that study for author place resembles electron microscope picture, show the bead bound between two Nd2Fe14B grain has cubic metre of heart of a body (Bcc) the construction of the photograph, the parallel strain line inside grain is the grid of C plane to resemble. Other magnetically hard material still have a lot of, for example Cu-Ni-Co alloy, Mn-Al-C alloy and Pt-Co alloy, still do not have below more than 10 kinds, be restricted to cannot introduce one by one at length. In permanent and magnetic material, having a few is volume is very minor and effect is very big " magnetism record material " (Magneticrecordingmaterial) : Farinose has γ - Fe2O3, CrO2, Fe4N, metallic pink is like alloyed powder of Fe pink, Fe-Co to wait, use the Wu Luyin belt, kinescope belt, industry such as diskette in great quantities; Additionally the Fe-Ni that makes filmy record, Fe-Ni-P, Fe-Ni-Cr, Fe-Ni-Co waits with at strong pattern diskette, co-Cr uses Wu Chuizhi record, tb-Fe-Co reachs Gd-Co to wait to read written magnetism smooth record to wait with Wu Ke. The place before magnetically hard material is like is narrated is device of one energy storage, should design only proper, it can do work, afore-mentioned " record " it is namely. Other applied circumstances include: Horn, motor, dynamo, plan implement, suck write the too numerous to mention one by one such as machine of device, magnetic separation. Temporarily magnetic material reachs his to use temporarily magnetic data is to be in be magnetized (when the coil that is circled outside its for example connects electrify to flow) hind present very strong magnetism, magnetizing field moves after dividing, the material of the degauss on the horse. Accordingly, can use on alternating current machine, even the applied circumstance of Wu Gaopin and UHF. Its use the requirement that go up is to guide magnetism rate and Bs value heal Gao Yujia, hc value heals low more beautiful (accordingly B × H is worth -- delegate magnetism caustic, more small) . For the course with development, temporarily magnetic material (namely soft magnetism material) earlier than magnetically hard material, and achievement relatively plentiful and substantial. For example pure iron itself is namely very the soft magnetism material of beautiful, begin to use namely from 19 centuries end, current dosage is very big still. Alloy of acting 1910 Fe-Ni already came out by invention of lab of American shellfish Er namely, call later guide high magnetism alloy (Permalloy) ; Take the place of to 1950 0 values of its μ (see a picture 2) already can be as high as 100, 000, call superconductive magnetism alloy (Supermalloy) . The effect that its magnetism suffers nickel content, make friends to extend to anneal means to wait is very big. Silicon steel piece initiate at 1900 around, come to made silicon steel of set prescription tropism 1930 piece since, it already became electric machinery to use the main trend of soft magnetism alloy. Because these soft alloy fasten conductor, suit the occasion that uses at low frequency only mostly. Material of ferrite soft magnetism is given priority to with department of pointed spar brilliant; General pattern is MFe2O4, m is diatomic ion, be like Mn++ , Zn++ , Ni++ , Cu++ , Mg++ , Co++ , wait at Fe++ even, for example at present the commonnest on market (Mn, zn)Fe2O4, (Ni, zn) .

Fe2O4 and (Mn, mg)Fe2O4. Because of ferrite soft magnetism material fastens oxide, resistance is great, applicable Wu Gaopin (the circumstance under 100MHz. If ultrahigh frequency, be like 100MHz ～ 500GHz (microwave limits) needing Zhe Liu stone is iron oxygen magnet -- Y3Fe5O12 and its ramification. 1958, dewey is neat (Duwez) invention noncrystalline alloy (Amorphousalloy) since device, 〔 of the alloy that be not brilliant calls metallic glass again (Metallicglass) the magnetism of 〕 and mechanical sex special suffer take seriously, and at 1970 ～ upsurge of very big a research is formed between 1980. American Allied company at 1974, begin to roll out commercial to be not brilliant small band, its Bs is as high as 16kG, hc is dinky (0.

01Oe is the following) , resistor relatively silicon steel piece tall, because this uses it to make transformer, magnetism caustic is far low at silicon steel piece person, for most the below one for generations that is valued is soft magnetic material. Weak magnetic data applies extensively at following each respect: One communication respect -- club of inductor, filter, antenna. Respect of 2 electric power -- transformer, motor, dynamo, block flows implement etc. Side of product of 3 consumption sex -- television deflection yoke and gallop return circle of streamline of transformer, block to wait. Respect of 4 magnetic head -- recording uses magnetic head (guide high magnetism alloy) , kinescope uses magnetic head (Fe-Si-Al alloy) , computer uses magnetic head (Mn-Zn ferrite) etc. 5 other utility are obstructed like magnetism implement, magnetic core of magnetism amplifier, switch and advanced electro-magnet. Magnetic material is the material that more than 1 appearance turn covers a metal to reach metalloid (pottery and porcelain) , bead of filmy, pink reachs a makings; Its application range is wide reach appliance of mechanical, electric machinery, electron, information, traffic, family expenses; The foundation that its study depend on reachs material project at science of solid-state physics, material. Accordingly, magnetic material is one kind " attraction is very strong " material, it is in " compatible and harbour " in fast thrive. The magnetic data industry of our country already had history of nearly 20 years, magnetic data research is only more than 10 years of histories, although small also have result, but as advanced as industry country is compared, still lag behind very far, need government, business circles and academia many sided cooperate, throw manpower, financial capacity, in order to promote the technology of magnetic material administrative levels. By at it the technology that is diversification, its promote the progress that also can drive other and relevant technology. The attention of our neighbour Japan to magnetic material, advocate with investment, can borrows lens for ours. Answerer: Tutu9454- blackart apprentice one class 3-219:29 magnetic material point to the stuff that has strong magnetism and project application value. Can divide in the main for: " permanent and magnetic material " , " temporarily magnetic material " reach " half permanent and magnetic material " 3 kinds big. They apply widely go up at the industry such as electron, electric machinery, information, machinery and traffic. The character of the origin of magnetism of article brief introduction, of all kinds magnetic material and function. Magnetic material (Magneticmaterials) fasten our week to meet with the material of can be found everywhere. Markedder, be like white board disk of the magnet below the magnet that go up, magnetic Chinese checkers, compass, tape, magnetic head, gentle style is waited a moment; Have additionally manier package the magnetic data in face of certain device Xuan , if motor, television, transformer, car waits interior a moment, by no means an isolated case. Can say, magnetic material already the life be closely bound up with modern. Inside the domain of material science, its classify is in " electronic material " Xuan face (wait with conductor, dielectric, semiconductor paratactic) . But the stuff that has magnetism covers material of metallic stuff, pottery and porcelain again, even at high polymer material. Its configuration still includes a material (B1uk) , powdery body (Particulate) reach film (Thinfilm) etc. Because this is magnetic,material itself is the stuff that has diversity part. For the viewpoint with physics, any material are magnetic material, that is to say, material of avery kind of has certain magnetism appearance. Some will be quits inside magnetic field intensity of one fraction magnetic field, appear " diamagnetic " (Diamagnetism) , be like copper; Some has inside magnetic field tiny induction, appear " paramagnetic " (Paramagnetism) , be like air; Some produces very strong magnetic amount in induction of the meeting inside magnetic field -- call magnetization to measure (Magnetization) , present ferromagnetism (Ferromagnetism, weigh ferromagnetic again) or ferrimagnetism (Ferrimagnetism, say again inferior ferromagnetic) etc phyletic and various. On industry, provide ferromagnetic only or inferior the material ability of ferromagnetic tries to use. But go up in physics, chemistry and medicine, the magnetism of other type also has very big use. The most interesting example is, the magnetism resonance of element of human body organ is used on medicine, can make systemic checkup quickly, by organic element " magnetic " , can detect of pathological changes have without, uses device is called MRI (Magneticresonanceimaging) . Here, plan to introduce the ferromagnetic Ji Yajiang with industrial application greater value only magnetic material (permanent reach temporarily magnetic material; Half permanent person sort and application are less, be restricted not to talk at length) . Magnetic origin till 20 centuries previously, people (include a scientist) magnetic to material understanding, won't be in than our ancestor hundreds, even the understanding before Wu Shu chiliad is good go to that Xuan . Come more than 70 years recently, the physical home that relies on to write a lot of sufferring to cross close science to train, chemist and mathematician try hard ceaselessly, eventually can gradually unlock its mysterious veil, peep its panorama. Before letting our abide write virtuous the origin that the course will come to understand magnetism. Be informed by the experiment, have between two magnetic pole be sucked or exclusive power, call magnetic force. Accordingly by force measure, can be informed " magnetism " size. Strong can have moment of force, because the moment of force since magnetism place is called " magnetic moment " (Magneticmoment) . Inchoate scientist (for example the person such as Faraday, Courier) the size that tries to measure corporeal place to contain magnetic moment inside magnetic field and the relation that its change along with temperature, discover the different reaction of different material thereby. The amount that one object place contains magnetic moment is called " magnetization is measured " . The magnetization amount that unit magnetic field can cause is called " magnetic susceptibility " (Magneticsusceptibility) , concern to the ration of temperature by magnetic susceptibility, we to be able to be defined diamagnetic, paramagnetic those who reach ferromagnetic to wait is different. But why such? Still do not have the answer. Above all, is magnetic moment assorted Zuo ? If break up magnet again and again, the grain that every get anew all is one new magnet, have south, north (N, S) extremely, break up the smallest and still can retain N, S is polar it is magnetic moment namely. Current, we are foregone electronic spin or revolution, cause this to plant most subsection (be just like electric current to circle coil flow to create magnetic field) . In other words, magnetic moment is electronic motion (revolution, rotation) , the net amount that was not offsetted, i.e. is magnetism Tuo (Magneticspin) net value. Remove diamagnetic material beyond, all and other material has inside magnetic field more or less magnetic moment, measure OK and mensurably, they contain very apparent ground magnetic is atomic (element) . Is that Zuo ferromagnetic how Zuo comes? Why contain magnetic atom likewise and have a plenty of ferromagnetic, is some done not have however? 1907, wei Si (Weiss) repeat house grain at the experiment 1895, cooperate mathematician blue ancient prose again (Langeuim) academic, hypothesis is magnetic " element " (think the element is material at that time most subsection) have interaction, call molecular field (Molecularfield) , bold conclude the molecular field that is not ferromagnetic material is very small, and the molecular field of ferromagnetic material is very big, make to enough greatly " element " magnetic moment is the same as to arrange and amount to saturation. Temperature nods high to Courier (make up note: Ferromagnetism material turns into by ferromagnetic paramagnetic the temperature when, call Courier to nod) when above, the permutation that heat energy destroyed molecular field action, make magnetic " element " confused, it is namely paramagnetic. In that case, why won't the ferromagnetic element such as major iron, cobaltic, nickel attract other iron, cobaltic, nickel? Since their interior already magnetized saturation, should can regarding very strong permanent magnet as ability is. Wei Si puts forward another bold hypothesis again, that is content department to reduce freedom can in order to amount to stable change, can raise chaos to spend. Ferromagnetic material interior is divided automatically into a lot of zonule, call magnetism area (Magneticdomain) . Direction is being magnetized inside same magnetism area is consistent, the magnetization way of different magnetism interval is different and show a disorder to change, reason each other is quits, common sense does not have magnetism to it, try to magnetize inside magnetic field only, break the troubled waters of magnetism area, ability experiences its ferromagnetic. The experiment of later generations (1931) confirm this one " fatidical " (see a picture one) , make Wei Si name hangs down through the ages, its beg the principle that the manner of pursue one's studies of card is humanness take delight in talking about more bold hypothesis, carefully. 1948, wei Si's pupil Neal (N é El) continue his research, discover magnetic moment of certain material atomic gets crystallization check the impact is very big, and the action of molecular field is very strong, for what lose, the magnetization way that brings about photograph adjacent atom to list is opposite. If size is equal completely quits, appear " turn over ferromagnetic " (Antiferromagnetism) . If size differs, appear " inferior ferromagnetic " ; So far, of material " magnetism " phenomenal principle already was announced roughly, er is in the Buddhist nun to had the honor to win Nobel physics award 1970 consequently. The magnetism phenomenon of magnetic material by magnetism the growth and decline of the area is decided. The interface between magnetism area and magnetism area calls magnetism area wall (Domainwall) , tuo of the magnetism inside its turns to another direction gradually by a direction, it is very thin, have tens of coming only hundreds dust (Å ) . If the magnetism area wall of magnetic material can follow adscititious magnetic field change and move at any time, this material is very easy namely saturation be goinged to by magnetization, very easy also degauss; Conversely, if try the motion of wall of area of block up magnetism, be gone to by magnetization after saturation this material not easy by degauss. Former present temporary magnetism, latter presents permanent magnetism. The job that magnetic material learns the home is in namely at: Use metallurgy of engineering of solid-state physics, material, physics, mechanical metallurgy to wait learn manage or skill, the part that controls magnetic material, microstructure and make its property closes to need at place. Permanent and magnetic material and the actor bad that its use magnetic data constant with magnetic hysteresis curve (Hysteresisloop, see a picture 2) , of the data presentation that presents. Watch of the OBs on the graph magnetizes a curve, call at the tangent slope of origin on its guide magnetism is led first (Initialpermeability, µo) , secant slope representing's specific B ／ H (intensity of magnetic field of magnetic induction ／ ) ratio, the biggest person it is namely the biggest guide magnetism is led (µm) . Bs dot represents saturated magnetic induction (Saturationinduction) unit with 1000 gauss (KG) express; Br dot is rudimental magnetic induction; Hc dot is called protect magnetic force or Coerciveforce of 〔 of force of correct magnetic retentivity, the unit is Oe or KOe, 1Oe comparatives at (4 π of 1000 ／ ) 〕 of A ／ M. Allow to represented one specific B × H to be worth on the 2nd quadrantal magnetic hysteresis curve (place of umbriferous to B, H line surrounds an area) , its are the biggest person call the biggest magnetism to be able to accumulate 〔 Maximumenergyproduct, logogram is (BH) M, unit G.

Oe, with millionfold watch it is MGOe 〕 . Exquisite Hc, Br reachs permanent and magnetic material (BH) M has healed greatly more, especially (BH) M, the energy of interiorly of keep in storage of the place after it is magnetized on behalf of this magnet, (BH) M value represents it to be able to do work external more greatly more, resemble never dried up batteries is same, if Hc is quite big (above of thousands of Oe) , courier temperature is quite high, it not easy by disappear (retreat) magnetism. 200Oe of ＞ of the Hc on the project person, can call permanent magnet. 19 centuries end comes at the beginning of 20 centuries, practicable is permanent magnet quenchs only carbolic steel. Carbolic steel quenchs sclerotic, hc lifts namely, more hard person Hc heals tall, permanent magnetism weighs reason again " hard " magnetic; Conversely anneal bate person present temporary magnetism, or " soft " magnetic. Quench steel Hc has 50 ～ 70Oe only, (BH) M has 0 only.

2 ～ 0.

3MGOe. 1916, the scientist adds Cr, W, Co inside carbolic steel, make Hc is added to 145 ～ 250Oe, (BH) M is close at 1MGOe, at that time it is very big breakthrough. 3 islands invented day person 1931 Fe-Ni-Al3 yuan alloy magnet, hc is as high as 500Oe (BH) M is amounted to 1.

4MGOe, open the entrance door that latter-day magnetically hard material develops. Give priority to with Fe-Al-Ni, add the Alnico alloy that the element such as Co, Cu, Si, Ti is improved and becomes, till the mainstream that permanent magnet is all the time before 1970. The rule that Jie alloy devises material scientist, control its to change, make generation leaves decompose reaction (Spinodaldecomposition) ; Cooling inside magnetic field, the way of photograph edge magnetic field that makes disclose earnings grows and get the outstanding magnet with different square very tall sex, hc amounts to 600 ～ 2000Oe, (BH) M is 3 ～ 12MGOe, what Jie alloy constitutes cent and heat treatment and can adjust magnetic data is characteristic. At this late hour, although update the permanent magnetism of type or valence cheap to already replaced gradually in great quantities, but its very stable magnetism (applicable comes the high temperature of 500 ℃ , make it is in certain and specific application (like microwave communication) on, fall into disuse not easily still. The alloy of Fe-Cr-Co permanent magnetism of acting 1970 invention uses the principle of Alnico to be designed namely, its magnetism also comparatives with Alnico alloy, the author ever had made old research, graph 3 show namely use magnetic field heat treatment, make of Fe28Cr-12Co-Ti alloy from the case that resolves direction of edge magnetic field to arrange. Decompose the grain that come out average diameter makes an appointment with 300Å , average length makes an appointment with 1200Å , the motion that magnetism area wall is inside its is extremely difficult, reason Hc cost is very high, become permanent magnet. 1932 ～ between 1938, the magnetic oxide that in day, carry on one's shoulder two ground begin to develop -- ferrite (Ferrites) , for one of mainstreams of permanent now magnetic material. The bases of ferrite is Ba0.

6Fe2O3 reachs Sr0.

6Fe2O3, belonging to Wu Liufang brilliant is; Its Hc is made an appointment with 1.

8 ～ 3.

2kOe, br is made an appointment with 2.

2 ～ 4.

3, (BH) M is made an appointment with 1.

0 ～ 4.

0MGOe (inspect additive to reach install Cheng to wait and different) . By at valence cheap, make it is easy to take, application is very wide, at present Taiwan month needs 2, more than tons 000, about 3 ／ 4 self-restrained. 1969, rare earth of success of material scientist development - the permanent magnet that cobalt changes thing, for permanent magnet open up another new scope of operation. Come nearly 20 years, permanent magnet has rare land great progress. From the earliest SmCo5 alloy Sm(Co, fe, cu, zr)7.

2-8.

5 (namely Sm2CO17) alloy, the Nd2Fe14B alloy to recently (rose 1984) , magnetism can accumulate the 20MGOe from record-breaking (SmCo5) to 30MGOe (Sm2Co17) arrive again 50MGOe (Nd-Fe-B alloy) , present the progress of saltant type, this is the research of science of Gui Gongwu material and development. Home is in at present the research of this respect and development work are as synchronous as international already, industry is produced also spread out, for very potential high-tech industry. Graph the tall solution of the 4 Nd-Fe-B alloy that study for author place resembles electron microscope picture, show the bead bound between two Nd2Fe14B grain has cubic metre of heart of a body (Bcc) the construction of the photograph, the parallel strain line inside grain is the grid of C plane to resemble. Other magnetically hard material still have a lot of, for example Cu-Ni-Co alloy, Mn-Al-C alloy and Pt-Co alloy, still do not have below more than 10 kinds, be restricted to cannot introduce one by one at length. In permanent and magnetic material, having a few is volume is very minor and effect is very big " magnetism record material " (Magneticrecordingmaterial) : Farinose has γ - Fe2O3, CrO2, Fe4N, metallic pink is like alloyed powder of Fe pink, Fe-Co to wait, use the Wu Luyin belt, kinescope belt, industry such as diskette in great quantities; Additionally the Fe-Ni that makes filmy record, Fe-Ni-P, Fe-Ni-Cr, Fe-Ni-Co waits with at strong pattern diskette, co-Cr uses Wu Chuizhi record, tb-Fe-Co reachs Gd-Co to wait to read written magnetism smooth record to wait with Wu Ke. The place before magnetically hard material is like is narrated is device of one energy storage, should design only proper, it can do work, afore-mentioned " record " it is namely. Other applied circumstances include: Horn, motor, dynamo, plan implement, suck write the too numerous to mention one by one such as machine of device, magnetic separation. Temporarily magnetic material reachs his to use temporarily magnetic data is to be in be magnetized (when the coil that is circled outside its for example connects electrify to flow) hind present very strong magnetism, magnetizing field moves after dividing, the material of the degauss on the horse. Accordingly, can use on alternating current machine, even the applied circumstance of Wu Gaopin and UHF. Its use the requirement that go up is to guide magnetism rate and Bs value heal Gao Yujia, hc value heals low more beautiful (accordingly B × H is worth -- delegate magnetism caustic, more small) . For the course with development, temporarily magnetic material (namely soft magnetism material) earlier than magnetically hard material, and achievement relatively plentiful and substantial. For example pure iron itself is namely very the soft magnetism material of beautiful, begin to use namely from 19 centuries end, current dosage is very big still. Alloy of acting 1910 Fe-Ni already came out by invention of lab of American shellfish Er namely, call later guide high magnetism alloy (Permalloy) ; Take the place of to 1950 0 values of its μ (see a picture 2) already can be as high as 100, 000, call superconductive magnetism alloy (Supermalloy) . The effect that its magnetism suffers nickel content, make friends to extend to anneal means to wait is very big. Silicon steel piece initiate at 1900 around, come to made silicon steel of set prescription tropism 1930 piece since, it already became electric machinery to use the main trend of soft magnetism alloy. Because these soft alloy fasten conductor, suit the occasion that uses at low frequency only mostly. Material of ferrite soft magnetism is given priority to with department of pointed spar brilliant; General pattern is MFe2O4, m is diatomic ion, be like Mn++ , Zn++ , Ni++ , Cu++ , Mg++ , Co++ , wait at Fe++ even, for example at present the commonnest on market (Mn, zn)Fe2O4, (Ni, zn) .

Fe2O4 and (Mn, mg)Fe2O4. Because of ferrite soft magnetism material fastens oxide, resistance is great, applicable Wu Gaopin (the circumstance under 100MHz. If ultrahigh frequency, be like 100MHz ～ 500GHz (microwave limits) needing Zhe Liu stone is iron oxygen magnet -- Y3Fe5O12 and its ramification. 1958, dewey is neat (Duwez) invention noncrystalline alloy (Amorphousalloy) since device, 〔 of the alloy that be not brilliant calls metallic glass again (Metallicglass) the magnetism of 〕 and mechanical sex special suffer take seriously, and at 1970 ～ upsurge of very big a research is formed between 1980. American Allied company at 1974, begin to roll out commercial to be not brilliant small band, its Bs is as high as 16kG, hc is dinky (0.

01Oe is the following) , resistor relatively silicon steel piece tall, because this uses it to make transformer, magnetism caustic is far low at silicon steel piece person, for most the below one for generations that is valued is soft magnetic material. Weak magnetic data applies extensively at following each respect: One communication respect -- club of inductor, filter, antenna. Respect of 2 electric power -- transformer, motor, dynamo, block flows implement etc. Side of product of 3 consumption sex -- television deflection yoke and gallop return circle of streamline of transformer, block to wait. Respect of 4 magnetic head -- recording uses magnetic head (guide high magnetism alloy) , kinescope uses magnetic head (Fe-Si-Al alloy) , computer uses magnetic head (Mn-Zn ferrite) etc. 5 other utility are obstructed like magnetism implement, magnetic core of magnetism amplifier, switch and advanced electro-magnet. Magnetic material is the material that more than 1 appearance turn covers a metal to reach metalloid (pottery and porcelain) , bead of filmy, pink reachs a makings; Its application range is wide reach appliance of mechanical, electric machinery, electron, information, traffic, family expenses; The foundation that its study depend on reachs material project at science of solid-state physics, material. Accordingly, magnetic material is one kind " attraction is very strong " material, it is in " compatible and harbour " in fast thrive. The magnetic data industry of our country already had history of nearly 20 years, magnetic data research is only more than 10 years of histories, although small also have result, but as advanced as industry country is compared, still lag behind very far, need government, business circles and academia many sided cooperate, throw manpower, financial capacity, in order to promote the technology of magnetic material administrative levels. By at it the technology that is diversification, its promote the progress that also can drive other and relevant technology. The attention of our neighbour Japan to magnetic material, advocate with investment, can borrows lens for ours. Reference material 1.

B.

D.

Cullity, introductiontoMagneticMaterials, addison-WesleyPub.

Co.

, 1972.

2.

" magnetic material " data of technology of institute of data of technology academy industry Jin Chongxun taught 1987 project of science of material of Wu Qinghua university is answerer: Enchanter of Babi20boy- learn on job 3 class 3-219:25--------------------------------------------------------------------------------[summary] magnetic material points to the stuff that has strong magnetism and project application value. Can divide in the main for: " permanent and magnetic material " , " temporarily magnetic material " reach " half permanent and magnetic material " 3 kinds big. They apply widely go up at the industry such as electron, electric machinery, information, machinery and traffic. The character of the origin of magnetism of article brief introduction, of all kinds magnetic material and function. Magnetic material (Magneticmaterials) fasten our week to meet with the material of can be found everywhere. Markedder, be like white board disk of the magnet below the magnet that go up, magnetic Chinese checkers, compass, tape, magnetic head, gentle style is waited a moment; Have additionally manier package the magnetic data in face of certain device Xuan , if motor, television, transformer, car waits interior a moment, by no means an isolated case. Can say, magnetic material already the life be closely bound up with modern. Inside the domain of material science, its classify is in " electronic material " Xuan face (wait with conductor, dielectric, semiconductor paratactic) . But the stuff that has magnetism covers material of metallic stuff, pottery and porcelain again, even at high polymer material. Its configuration still includes a material (B1uk) , powdery body (Particulate) reach film (Thinfilm) etc. Because this is magnetic,material itself is the stuff that has diversity part. For the viewpoint with physics, any material are magnetic material, that is to say, material of avery kind of has certain magnetism appearance. Some will be quits inside magnetic field intensity of one fraction magnetic field, appear " diamagnetic " (Diamagnetism) , be like copper; Some has inside magnetic field tiny induction, appear " paramagnetic " (Paramagnetism) , be like air; Some produces very strong magnetic amount in induction of the meeting inside magnetic field -- call magnetization to measure (Magnetization) , present ferromagnetism (Ferromagnetism, weigh ferromagnetic again) or ferrimagnetism (Ferrimagnetism, say again inferior ferromagnetic) etc phyletic and various. On industry, provide ferromagnetic only or inferior the material ability of ferromagnetic tries to use. But go up in physics, chemistry and medicine, the magnetism of other type also has very big use. The most interesting example is, the magnetism resonance of element of human body organ is used on medicine, can make systemic checkup quickly, by organic element " magnetic " , can detect of pathological changes have without, uses device is called MRI (Magneticresonanceimaging) . Here, plan to introduce the ferromagnetic Ji Yajiang with industrial application greater value only magnetic material (permanent reach temporarily magnetic material; Half permanent person sort and application are less, be restricted not to talk at length) . Magnetic origin till 20 centuries previously, people (include a scientist) magnetic to material understanding, won't be in than our ancestor hundreds, even the understanding before Wu Shu chiliad is good go to that Xuan . Come more than 70 years recently, the physical home that relies on to write a lot of sufferring to cross close science to train, chemist and mathematician try hard ceaselessly, eventually can gradually unlock its mysterious veil, peep its panorama. Before letting our abide write virtuous the origin that the course will come to understand magnetism. Be informed by the experiment, have between two magnetic pole be sucked or exclusive power, call magnetic force. Accordingly by force measure, can be informed " magnetism " size. Strong can have moment of force, because the moment of force since magnetism place is called " magnetic moment " (Magneticmoment) . Inchoate scientist (for example the person such as Faraday, Courier) the size that tries to measure corporeal place to contain magnetic moment inside magnetic field and the relation that its change along with temperature, discover the different reaction of different material thereby. The amount that one object place contains magnetic moment is called " magnetization is measured " . The magnetization amount that unit magnetic field can cause is called " magnetic susceptibility " (Magneticsusceptibility) , concern to the ration of temperature by magnetic susceptibility, we to be able to be defined diamagnetic, paramagnetic those who reach ferromagnetic to wait is different. But why such? Still do not have the answer. Above all, is magnetic moment assorted Zuo ? If break up magnet again and again, the grain that every get anew all is one new magnet, have south, north (N, S) extremely, break up the smallest and still can retain N, S is polar it is magnetic moment namely. Current, we are foregone electronic spin or revolution, cause this to plant most subsection (be just like electric current to circle coil flow to create magnetic field) . In other words, magnetic moment is electronic motion (revolution, rotation) , the net amount that was not offsetted, i.e. is magnetism Tuo (Magneticspin) net value. Remove diamagnetic material beyond, all and other material has inside magnetic field more or less magnetic moment, measure OK and mensurably, they contain very apparent ground magnetic is atomic (element) . Is that Zuo ferromagnetic how Zuo comes? Why contain magnetic atom likewise and have a plenty of ferromagnetic, is some done not have however? 1907, wei Si (Weiss) repeat house grain at the experiment 1895, cooperate mathematician blue ancient prose again (Langeuim) academic, hypothesis is magnetic " element " (think the element is material at that time most subsection) have interaction, call molecular field (Molecularfield) , bold conclude the molecular field that is not ferromagnetic material is very small, and the molecular field of ferromagnetic material is very big, make to enough greatly " element " magnetic moment is the same as to arrange and amount to saturation. Temperature nods high to Courier (make up note: Ferromagnetism material turns into by ferromagnetic paramagnetic the temperature when, call Courier to nod) when above, the permutation that heat energy destroyed molecular field action, make magnetic " element " confused, it is namely paramagnetic. In that case, why won't the ferromagnetic element such as major iron, cobaltic, nickel attract other iron, cobaltic, nickel? Since their interior already magnetized saturation, should can regarding very strong permanent magnet as ability is. Wei Si puts forward another bold hypothesis again, that is content department to reduce freedom can in order to amount to stable change, can raise chaos to spend. Ferromagnetic material interior is divided automatically into a lot of zonule, call magnetism area (Magneticdomain) . Direction is being magnetized inside same magnetism area is consistent, the magnetization way of different magnetism interval is different and show a disorder to change, reason each other is quits, common sense does not have magnetism to it, try to magnetize inside magnetic field only, break the troubled waters of magnetism area, ability experiences its ferromagnetic. The experiment of later generations (1931) confirm this one " fatidical " (see a picture one) , make Wei Si name hangs down through the ages, its beg the principle that the manner of pursue one's studies of card is humanness take delight in talking about more bold hypothesis, carefully. 1948, wei Si's pupil Neal (N é El) continue his research, discover magnetic moment of certain material atomic gets crystallization check the impact is very big, and the action of molecular field is very strong, for what lose, the magnetization way that brings about photograph adjacent atom to list is opposite. If size is equal completely quits, appear " turn over ferromagnetic " (Antiferromagnetism) . If size differs, appear " inferior ferromagnetic " ; So far, of material " magnetism " phenomenal principle already was announced roughly, er is in the Buddhist nun to had the honor to win Nobel physics award 1970 consequently. The magnetism phenomenon of magnetic material by magnetism the growth and decline of the area is decided. The interface between magnetism area and magnetism area calls magnetism area wall (Domainwall) , tuo of the magnetism inside its turns to another direction gradually by a direction, it is very thin, have tens of coming only hundreds dust (Å ) . If the magnetism area wall of magnetic material can follow adscititious magnetic field change and move at any time, this material is very easy namely saturation be goinged to by magnetization, very easy also degauss; Conversely, if try the motion of wall of area of block up magnetism, be gone to by magnetization after saturation this material not easy by degauss. Former present temporary magnetism, latter presents permanent magnetism. The job that magnetic material learns the home is in namely at: Use metallurgy of engineering of solid-state physics, material, physics, mechanical metallurgy to wait learn manage or skill, the part that controls magnetic material, microstructure and make its property closes to need at place. Permanent and magnetic material and the actor bad that its use magnetic data constant with magnetic hysteresis curve (Hysteresisloop, see a picture 2) , of the data presentation that presents. Watch of the OBs on the graph magnetizes a curve, call at the tangent slope of origin on its guide magnetism is led first (Initialpermeability, µo) , secant slope representing's specific B ／ H (intensity of magnetic field of magnetic induction ／ ) ratio, the biggest person it is namely the biggest guide magnetism is led (µm) . Bs dot represents saturated magnetic induction (Saturationinduction) unit with 1000 gauss (KG) express; Br dot is rudimental magnetic induction; Hc dot is called protect magnetic force or Coerciveforce of 〔 of force of correct magnetic retentivity, the unit is Oe or KOe, 1Oe comparatives at (4 π of 1000 ／ ) 〕 of A ／ M. Allow to represented one specific B × H to be worth on the 2nd quadrantal magnetic hysteresis curve (place of umbriferous to B, H line surrounds an area) , its are the biggest person call the biggest magnetism to be able to accumulate 〔 Maximumenergyproduct, logogram is (BH) M, unit G.

Oe, with millionfold watch it is MGOe 〕 . Exquisite Hc, Br reachs permanent and magnetic material (BH) M has healed greatly more, especially (BH) M, the energy of interiorly of keep in storage of the place after it is magnetized on behalf of this magnet, (BH) M value represents it to be able to do work external more greatly more, resemble never dried up batteries is same, if Hc is quite big (above of thousands of Oe) , courier temperature is quite high, it not easy by disappear (retreat) magnetism. 200Oe of ＞ of the Hc on the project person, can call permanent magnet. 19 centuries end comes at the beginning of 20 centuries, practicable is permanent magnet quenchs only carbolic steel. Carbolic steel quenchs sclerotic, hc lifts namely, more hard person Hc heals tall, permanent magnetism weighs reason again " hard " magnetic; Conversely anneal bate person present temporary magnetism, or " soft " magnetic. Quench steel Hc has 50 ～ 70Oe only, (BH) M has 0 only.

2 ～ 0.

3MGOe. 1916, the scientist adds Cr, W, Co inside carbolic steel, make Hc is added to 145 ～ 250Oe, (BH) M is close at 1MGOe, at that time it is very big breakthrough. 3 islands invented day person 1931 Fe-Ni-Al3 yuan alloy magnet, hc is as high as 500Oe (BH) M is amounted to 1.

4MGOe, open the entrance door that latter-day magnetically hard material develops. Give priority to with Fe-Al-Ni, add the Alnico alloy that the element such as Co, Cu, Si, Ti is improved and becomes, till the mainstream that permanent magnet is all the time before 1970. The rule that Jie alloy devises material scientist, control its to change, make generation leaves decompose reaction (Spinodaldecomposition) ; Cooling inside magnetic field, the way of photograph edge magnetic field that makes disclose earnings grows and get the outstanding magnet with different square very tall sex, hc amounts to 600 ～ 2000Oe, (BH) M is 3 ～ 12MGOe, what Jie alloy constitutes cent and heat treatment and can adjust magnetic data is characteristic. At this late hour, although update the permanent magnetism of type or valence cheap to already replaced gradually in great quantities, but its very stable magnetism (applicable comes the high temperature of 500 ℃ , make it is in certain and specific application (like microwave communication) on, fall into disuse not easily still. The alloy of Fe-Cr-Co permanent magnetism of acting 1970 invention uses the principle of Alnico to be designed namely, its magnetism also comparatives with Alnico alloy, the author ever had made old research, graph 3 show namely use magnetic field heat treatment, make of Fe28Cr-12Co-Ti alloy from the case that resolves direction of edge magnetic field to arrange. Decompose the grain that come out average diameter makes an appointment with 300Å , average length makes an appointment with 1200Å , the motion that magnetism area wall is inside its is extremely difficult, reason Hc cost is very high, become permanent magnet. 1932 ～ between 1938, the magnetic oxide that in day, carry on one's shoulder two ground begin to develop -- ferrite (Ferrites) , for one of mainstreams of permanent now magnetic material. The bases of ferrite is Ba0.

6Fe2O3 reachs Sr0.

6Fe2O3, belonging to Wu Liufang brilliant is; Its Hc is made an appointment with 1.

8 ～ 3.

2kOe, br is made an appointment with 2.

2 ～ 4.

3, (BH) M is made an appointment with 1.

0 ～ 4.

0MGOe (inspect additive to reach install Cheng to wait and different) . By at valence cheap, make it is easy to take, application is very wide, at present Taiwan month needs 2, more than tons 000, about 3 ／ 4 self-restrained. 1969, rare earth of success of material scientist development - the permanent magnet that cobalt changes thing, for permanent magnet open up another new scope of operation. Come nearly 20 years, permanent magnet has rare land great progress. From the earliest SmCo5 alloy Sm(Co, fe, cu, zr)7.

2-8.

5 (namely Sm2CO17) alloy, the Nd2Fe14B alloy to recently (rose 1984) , magnetism can accumulate the 20MGOe from record-breaking (SmCo5) to 30MGOe (Sm2Co17) arrive again 50MGOe (Nd-Fe-B alloy) , present the progress of saltant type, this is the research of science of Gui Gongwu material and development. Home is in at present the research of this respect and development work are as synchronous as international already, industry is produced also spread out, for very potential high-tech industry. Graph the tall solution of the 4 Nd-Fe-B alloy that study for author place resembles electron microscope picture, show the bead bound between two Nd2Fe14B grain has cubic metre of heart of a body (Bcc) the construction of the photograph, the parallel strain line inside grain is the grid of C plane to resemble. Other magnetically hard material still have a lot of, for example Cu-Ni-Co alloy, Mn-Al-C alloy and Pt-Co alloy, still do not have below more than 10 kinds, be restricted to cannot introduce one by one at length. In permanent and magnetic material, having a few is volume is very minor and effect is very big " magnetism record material " (Magneticrecordingmaterial) : Farinose has γ - Fe2O3, CrO2, Fe4N, metallic pink is like alloyed powder of Fe pink, Fe-Co to wait, use the Wu Luyin belt, kinescope belt, industry such as diskette in great quantities; Additionally the Fe-Ni that makes filmy record, Fe-Ni-P, Fe-Ni-Cr, Fe-Ni-Co waits with at strong pattern diskette, co-Cr uses Wu Chuizhi record, tb-Fe-Co reachs Gd-Co to wait to read written magnetism smooth record to wait with Wu Ke. The place before magnetically hard material is like is narrated is device of one energy storage, should design only proper, it can do work, afore-mentioned " record " it is namely. Other applied circumstances include: Horn, motor, dynamo, plan implement, suck write the too numerous to mention one by one such as machine of device, magnetic separation. Temporarily magnetic material reachs his to use temporarily magnetic data is to be in be magnetized (when the coil that is circled outside its for example connects electrify to flow) hind present very strong magnetism, magnetizing field moves after dividing, the material of the degauss on the horse. Accordingly, can use on alternating current machine, even the applied circumstance of Wu Gaopin and UHF. Its use the requirement that go up is to guide magnetism rate and Bs value heal Gao Yujia, hc value heals low more beautiful (accordingly B × H is worth -- delegate magnetism caustic, more small) . For the course with development, temporarily magnetic material (namely soft magnetism material) earlier than magnetically hard material, and achievement relatively plentiful and substantial. For example pure iron itself is namely very the soft magnetism material of beautiful, begin to use namely from 19 centuries end, current dosage is very big still. Alloy of acting 1910 Fe-Ni already came out by invention of lab of American shellfish Er namely, call later guide high magnetism alloy (Permalloy) ; Take the place of to 1950 0 values of its μ (see a picture 2) already can be as high as 100, 000, call superconductive magnetism alloy (Supermalloy) . The effect that its magnetism suffers nickel content, make friends to extend to anneal means to wait is very big. Silicon steel piece initiate at 1900 around, come to made silicon steel of set prescription tropism 1930 piece since, it already became electric machinery to use the main trend of soft magnetism alloy. Because these soft alloy fasten conductor, suit the occasion that uses at low frequency only mostly. Material of ferrite soft magnetism is given priority to with department of pointed spar brilliant; General pattern is MFe2O4, m is diatomic ion, be like Mn++ , Zn++ , Ni++ , Cu++ , Mg++ , Co++ , wait at Fe++ even, for example at present the commonnest on market (Mn, zn)Fe2O4, (Ni, zn) .

Fe2O4 and (Mn, mg)Fe2O4. Because of ferrite soft magnetism material fastens oxide, resistance is great, applicable Wu Gaopin (the circumstance under 100MHz. If ultrahigh frequency, be like 100MHz ～ 500GHz (microwave limits) needing Zhe Liu stone is iron oxygen magnet -- Y3Fe5O12 and its ramification CNC Milling