高溫磁性材料

1、 高溫磁性材料 材料科學與工程學院 北京航空航天大學材料的性質(zhì)1. 力學性質(zhì)2. 物理性質(zhì)2.1 電學性質(zhì) 2.2 磁學性質(zhì)2.3 光學性質(zhì)2.4 熱學性質(zhì)2.5 超導電性性質(zhì)使用性能合成/制備結(jié)構(gòu)/成份材料科學四要素Maglev吸引力和排斥力磁場的產(chǎn)生電子繞核轉(zhuǎn)動和自旋磁性材料的應(yīng)用鐵磁性反鐵磁性亞鐵磁性物質(zhì)的磁性磁疇-Magnetic Domain磁化過程和磁疇運動:磁疇和靜磁能磁疇照片磁滯回線主要參數(shù): Hc(矯頑力); Bs(飽和磁化強度)軟磁材料永磁材料磁性材料的主要種類Various soft magnetic materialsIronFe-Si alloysFe-Ni allo

2、ysFe-Co alloysSoft ferrites MoFe2O3, M,ZnFe2O4Amorphous alloys (Fe72Co8Si5B15)Nanocrystalline alloys (Fe73.5Cu1Nb3Si13.5B9)Various hard magnetic materialsFe & Cot steelNi and Co alloys (alnicos)Oxides (Hard ferrites)Rare earth inter-metallic compoundsExamples of modern permanent magnetsSmCo5 type (s

3、intered)Sm2Co17 type (sintered)Bonded RE cobalt magnets(bonded SmCo5, Sm2Co17)Sintered Nd-Fe-B magnets Bonded Nd-Fe-B magnets 高溫永磁材料An ion propulsion engine incorporating high-temp SmCo magnets (red) powered the Deep Space 1 probe. 氙(Xe)離子空間推進器ADVANCED MAGNTSPhase Diagrams: Binary AlloysIn the binar

4、y Sm-Co system the allowed deviations from the alloys stoichiometries are limited.The eutectoid decomposition of the 1:5 phase is extremely slow and not likely to occur in the practical alloys.Typical magnets have the composition Sm(Co,Fe,Cu,Zr)zZr allows greater deviations from the stoichiometry. A

5、t high temperatures, the continuous range of the 1:7 structure stretches from 1:5 to 2:17*.At lower temperatures this solution phase will decompose into 2:17 and 1:5._* S. Derkaoui, N. Valignat and C.H. Allibert, J. Alloys and Compounds 232 (1996) 296. 1150 oCPhase Diagrams: Effect of ZrCrystallogra

6、phy of PhasesThe hexagonal 1:5 structure consists of alternating Sm-Co and Co layers.The 2:17(R) structure is one of several 1:5 derivatives with ordered Co dumbbells.In the 2:17 magnets, the Cu and Fe atoms occupy the individual Co sites, while the Zr atoms occupy the dumbbell sites (i.e. the Sm si

7、tes of the parent 1:5 lattice).If extra Co atoms added, pairs of them replace the larger Sm atoms as the so-called dumbbells. Random replacement does not change the lattice symmetry leading to the off-stoichiometric 1:5 stucture, sometimes called the 1:7 structure.1150 oCSm(CoFeCuZr) Hci= 14.5 kOe H

8、ci=36.0 kOe Cell Size=50nm Cell Size=110nmTag=700C Tag=850C 時效熱處理溫度的影響Sm(CobalFe0.1Cu0.088Zr0.04)8.5Cell size 35 nm 120 nm - Hc 5.6 kOe 32.0 kOe 0.4 kOe Aged at 850C 1h 9h 12h時效熱處理時間的影響Effect of Z-ratio: Sm(CobalFe0.224Cu0.088Zr0.033)zbacz=7.0, Hci=15 kOe z=8.5, Hci=35 kOe z=9.0, Hci=8 kOe.Cell size

9、: 88 nm 108 nm 237 nm 計算機硬盤以及微電子機械系統(tǒng)(MEMS)的小型化及高性能化關(guān)鍵技術(shù)之一: 磁性材料的小型化、高性能化和集成化磁性材料的應(yīng)用磁記錄材料磁記錄裝置原理圖Nanoparticles by the Cluster GunAMR3%AMR3%巨磁阻結(jié)構(gòu)Fe layer (FM)Cr layer (NM)Fe layer (FM)德國科學家彼得格林貝格爾(Peter Grunberg) 法國物理學家阿爾貝費爾(Albert Fert) 2007年諾貝爾物理學獎自旋閥Exchange-biased spin-valves were developed byDienyet al., Phys. Rev. B43, R1297(1991).隧道結(jié)-Tunneling Junction思考題：利用磁性原理，你如何設(shè)計磁懸浮列車？試分析 磁懸浮列車的優(yōu)缺點。2. 既然磁記錄密度和磁記錄單元尺寸有關(guān)，能否說 將磁記錄單元做的越小，磁記錄密度就會越高？思考題：利用磁性原理，你如何設(shè)計磁懸浮列車？試分析 磁懸浮列車的有缺點。答案：a. Contac