高性能软磁合金的研究进展EI北大核心CSCD

软磁材料是一种极为重要且应用十分广泛的能源材料,近年来,随着磁性元件的日益高频化和小型化,以及节能环保的号召,开发和研究高性能软磁材料具有重要意义。本工作概述了软磁合金的发展历史,重点归纳出各类软磁合金(包括传统软磁合金、非晶/纳米晶软磁合金、高熵软磁合金)的成分、微观组织、磁性能以及应用范围,并总结出不同软磁合金的优、缺点;指出典型合金的微观组织对合金软磁性能(尤其矫顽力)具有关键性的主导作用,进而探讨了影响软磁合金矫顽力的因素及其微观机制,发现控制晶粒尺寸(或纳米粒子尺寸)是获得低矫顽力的关键,并描述了矫顽力的微观影响机制在高熵软磁合金中的发展;最后,展望了高熵软磁合金因多主元混合的成分特性带来的组织多样化,更有利于实现对合金性能的调控,并有望作为新一代高温软磁体材料。     

Co-Pt永磁合金薄膜的研究进展

Co-Pt永磁合金薄膜具有矫顽力高、磁晶各向异性常数大、抗氧化和抗腐蚀性强等优点,因此在高密度磁记录、磁光存储等领域具有良好的应用前景并受到广泛关注。本文简述了Co-Pt永磁薄膜材料目前的研究工作,介绍了该类合金的结构特点和交换耦合作用机理,主要叙述了有关热处理工艺和第三元素添加对该化合物的磁性能影响。     

热处理对高矫顽力型FeCrCo合金性能的影响

FeCrCo合金系永磁合金具有良好的可加工性，适合制造磁性元器件。针对该合金矫顽力低的特点，本文讨一种高矫顽力型FeCrCo合金，从合金的热处理工艺入手，即传统的三步热处理，高温固溶处理、磁场热处理，分级回火处理，通过不同的实验条件下合金的性能变化情况阐明合金实用的处理工艺。     

高导磁纳米晶Fe67.9Cu0.5 Nb0.6Cr3V1Si14B13合金的高频磁性能

报道了新开发的纳米晶Fe67.9Cu0.5Nb0.6Cr3V1Si14B13合金的综合磁性能.新合金的直流起始磁导率和矫顽力水平分别为7.8×104和0.8Am-1.在Bm=0.3T,f=100kHz和Bm=0.2T,f=200kHz条件下,铁损分别为544kW·m-3和830kW·m-3,这可与纳米晶Fe73.5Cu1Nb3Si13.5B9的相比,但比优良的功率Mn-Zn铁氧体H7c4的低得多.在直到1MHz的频率范围内考查了弱场磁导率的频散特性.在f=20～103kHz和Bm=0.01～1.0T范围内,考查了高频矫顽力和Bm的关系.在f=20～103kHz和Bm=0.05～0.9T范围内,描述了铁损和f及Bm的关系.     

各向同性富铁Fe—Pt纳米晶薄膜的形成及其磁性

采用直流溅射多层结合退火技术，制备了不同富铁量的各向同性Fe－Pt纳米晶永磁薄膜。对这些永磁薄膜的研究表明：在500℃退火3min－10min得到的所有不同富Fe量的Fe－Pt永磁薄膜是各向同性的；它们的磁滞回线都显现单相的硬磁行为；所有的薄膜显示出剩磁增强效应，其剩磁随富Fe含量的增加而增大。磁力显微镜观测表明，在热退磁状态下Fe－Pt薄膜显现出不规则的模跨数个晶凿的岛状畴，其大小是平均晶粒尺寸的7倍－10倍。     

DEPENDENCE OF MAGNETISM OF Nd-Fe-B SINTERMAGNETS ON ORIENTATION MAGNETIC FIELD

The effect of the orientation magnetic field on the permanent magnetism of Nd-Fe-B sintermagnets is investigated. The results show that the variation law of mag-netism with orientation field obviosly changes at the critical orientation field and the in-tensity of the orientation field should be determined by the dimension ratio of the magnet for effectively utilizing its magnetic energv product.     

STUDY OF STRUCTURE, MAGNETIC PROPERTIES AND PREPARATION OF Sm_2Fe_(17)N_x POWDER WITH HIGH ENERGY PRODUCTS

The effects of hydrogenation before nitrogenization of Sm_2Fe_(17) alloy on structure andmagnetic properties of Sm_2Fe_(17)N_x powder are studied in this paper.The unit cell volume ofSm_2Fe_(17)increases by about 3.6% and many cracks occur in Sm_2Fe_(17) particles during the process of hydrogenation.The Sm_2Fe_(17)N_x powder treaed by hydrogenation thennitrogenization has the higher content of N and the better intrinsic and technological magnetic properties than that treated by nitrogenization directly.     

COERCIVITY AND ITS GRAIN SIZE DEPENDENCE IN CAST-HOT PRESSED Pr-Fe-B MAGNETS

Characteristics of magnetic hardening in cast-hot pressed magnet Pr_(19)Fe_(74.5)B_5Cu_(1.5)were stu-died.The microstructure features and virgin magnetization curve reveal a nucleation control-led coercivity mechanism.Regression analysis shows that the intrinsic coercivity variesinversely as the logarithm of the average grain size:_iH_c(MA/m)=1.7312-0.48161nd(μm)which confirms the randomness of nucleation of reversed domains and the statistical nature ofcoercivity,indicating that the decrease of grain size would reduce the average number of de-fects on its surface and lower the probability of magnetization reversal of a grain and the cu-mulative fraction of the grains that have reversed their magnetization.Coercivity is thus en-hanced.     

真空退火Co/Pt多层膜的结构、磁及磁光特性分析

本文用直流磁控溅射方法制备了Co／Pt多层膜,并对其进行了较为细致的真空退火处理,结果表明,适度的低温退火可增加Co／Pt多层膜的矫顽力,而并不削弱其磁滞克尔回线的矩形特征．当退火温度达到300℃以后,Co／Pt多层膜的矫顽力、垂直各向异性和克尔角将强烈下降,晶体结构的改善及应力的释放、晶粒的增长、层间原子扩散引起的Co层有效厚度减薄,进而居里温度的下降,分别是Co／Pt多层膜在低温、中温、高温退火过程中,磁及磁光性能变化的主要机制．     

Fe21Ni79合金纳米线阵列的制备与磁性

用交流电化学沉积方法,在多孔铝阳极氧化膜的柱形孔内制备直径约60 nm,长度约为9.7 μm的Fe₂₁Ni₇₉合金纳米线.采用扫描电镜、透射电镜、X射线衍射仪和振动样品磁强计对纳米线的形貌 、结构和磁学性质进行了测试.结果表明,Fe₂₁Ni₇₉纳米线排列有序,长径比可控,合金呈fcc结构.当将其在外磁场下进行垂直磁化时,磁滞回线出现较高的矩形比0.86,矫顽力达1203Oe.且随着退火温度升高,矫顽力迅速增大,500℃时达到最大值1315Oe,之后又随退火温度的升高而下降.矩形比也呈现类似的变化规律.