Fe基纳米晶软磁合金退火脆性的研究进展  

Research Progress on Annealing Embrittlement of Fe-based Nanocrystalline Soft Magnetic Alloys

作　　者：张国忠 李艳辉[1] 吴立成 张伟[1] ZHANG Guozhong;LI Yanhui;WU Licheng;ZHANG Wei(Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province),School of Materials Science and Engineering,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]大连理工大学材料科学与工程学院辽宁省凝固控制与数字化制备技术重点实验室

出　　处：《材料导报》2020年第3期165-171,共7页Materials Reports

基　　金：国家重点研发计划项目(2017YFB0903903);国家自然科学基金面上项目(51571047;51771039)~~

摘　　要：Fe基纳米晶软磁合金自1988年被发现以来,因其低矫顽力、高磁导率、低铁损、低磁致伸缩系数等优异特性,尤其是高频下突出的软磁性能一直受到广泛的关注;其中,Finemet合金已作为高频变压器等设备的铁心材料在工业生产中得到了应用。近年来,一系列高饱和磁感应强度的新型纳米晶软磁合金的研发,将进一步促进电子、电力设备的小型化和节能化。Fe基纳米晶软磁合金通常是由其前驱体非晶带材经退火处理结晶化制备获得。在热处理过程中带材会产生脆性,这不仅增加了铁心加工成形的难度,也使得铁心在实际工况下易失效,严重制约了其在工业生产中的广泛应用。因此,材料工作者对其退火脆性问题展开了研究,并取得了一系列成果。Fe基纳米晶软磁合金的退火脆化产生可分为两个阶段,即非晶前驱体在低于初始结晶化温度下退火导致结构弛豫引起的韧-脆性转变,以及结晶化后由α-Fe相析出引起的合金脆性增加。目前,评价带材的韧-脆性主要采用相对断裂应变(Relative strain at fracture,εf)和临界应力强度因子(KQ)这两个参量。虽然εf值的离散性较大,但由于测定方法简便且能够定量地反映合金的脆化程度而被广泛应用于带材退火脆性的研究。通常合金的退火脆性随α-Fe相体积分数的增加而增大,而细化α-Fe晶粒则有利于抑制合金的退火脆性倾向。当合金中α-Fe相体积分数在70%以下时,合金的硬度随α-Fe相体积分数的增加呈线性增长,此时硬度也可以间接地反映合金脆化的程度。添加合金元素、优化热处理工艺以及采用新型热处理方法等均可以细化纳米晶合金的组织结构,从而在一定程度上抑制其退火脆性倾向。本文综述了近年来有关Fe基纳米晶软磁合金的退火脆化机制、韧-脆性评价方法,分析了合金成分、热处理工艺、组织结构、退火脆性间的关系,总结�Since Fe-based nanocrystalline soft magnetic alloys were discovered in 1988,they have attracted increasing attention due to the excellentproperties including low coercivity,high permeability,low core loss,low magnetostriction coefficient,and especially outstanding soft magnetic properties in high frequency. Among them,Finemet alloys have been widely used as core materials in high-frequency transformer and other devices. In recent years,a series of new nanocrystalline soft magnetic alloys with high saturation magnetic flux density have been developed,which will promote the miniaturization and energy saving of the power and electronic equipment.The Fe-based nanocrystalline soft magnetic alloys are usually fabricated by annealing the amorphous ribbons. During annealing,the ribbons become brittle,which increases the difficulty to the processing and forming of the iron cores,and also causes the devices prone to failure in service,hence restricting their extensive applications in industry. Therefore,plenty of work on the annealing embrittlement of the alloys have been conducted,and a series of progress has been made.The process of the annealing embrittlement of the Fe-based nanocrystalline alloys includes two stages,i.e.,the ductile-to-brittle transition due to the structural relaxation of the amorphous precursor annealed below the primary crystallization temperature,and the further increase in the brittleness caused by the precipitation of α-Fe phase after crystallization. The relative strain at fracture( εf) and critical stress intensity factor( K Q)are commonly adopted to evaluate the brittle degree of the alloy ribbons. The εfis mainly employed to study the annealing embrittlement of the ribbons because it can quantitatively characterize the degree of the brittleness,and the test is simple,although the εfvalues are discrete to a certain degree. The increase in the volume fraction of the α-Fe phase usually aggravates the annealing embrittlement,while refining the α-Fe grain is beneficial to restrain the embrit

关 键 词：FE 基纳米晶软磁合金 退火脆性 非晶合金 热处理工艺 组织结构 

分 类 号：TG132.271[一般工业技术—材料科学与工程]