【摘要】 研究Ni基非晶软磁合金粉末在Ni-Zr二元相图上三个稳定化合物成分配方Ni7Zr2、Ni21Zr8、NiZr和两个共晶点Ni64Zr36、Ni36Zr64组分在机械合金化条件下的非晶合金形成能力和热稳定性。五种配方在一定的时间内都能形成非晶态合金;其中Ni64Zr36的过冷液相区间△Tx达到69.9K。用扫描电子显微镜(SEM)观察了不同球磨时间混合粉末的形貌,发现球磨时间对混合粉末的结构及颗粒形貌存在显著影响。随着球磨时间的增加,Ni、Zr颗粒都发生严重塑性变形,并且通过冷焊团聚起来,形成具有层状结构的复合颗粒。由于磨球的剧烈撞击,使得结构发生了严重的畸变,从而破坏了原有的有序结构而形成了无序结构。另外,在进一步的球磨过程中,合金的晶粒不断减小,形成高体积分数的晶界,而金属粉末不断的发生塑性变形,形成了点缺陷、位错等高密度缺陷,晶格发生严重的畸变,晶体自由能也相应不断上升,最后发生了非晶转变。磁性能测量表明合金粉末具有较好的软磁性能。更多还原

【Abstract】 The glass forming ability of five compound compositions based on the Ni-Zr phase diagram such as Ni7Zr2,Ni21Zr8,NiZr,Ni64Zr36 and Ni36Zr64 was studied under mechanical alloying conditions.The composite powders were performed in a Pulverisette 5 planetary mill using high purity argon at 1atm pressure in the same technical parameter.The structure of the powders was examined by X-ray diffraction(XRD) and the parameter of thermal stability was measured by differential thermal analysis(DTA).It is found that all the alloys form amorphous alloys,and the maximum undercooled liquid temperature region(ΔTx) among five alloys is 69.9K.Micrography of ball-milled powders after selected MA processing time were observed using scanning electron microscopy.The results show that the milling time has significant influence on the powder structure and particle configuration.As the MA time increases,the Ni and Zr powders particles are heavy plastic deformed,getting flattened to platelet/pancake shapes,by the micro-forging process.These flattened particles get cold welded together and form a composite lamellar structure of the constituent metals.Because of acute impacts during the ball milling,particle configuration of the Ni and Zr powders are seriously abnormal deformed,which destroys intrinsic order configuration and transforms out of order.In addition,the average grain size of alloy powders decreases continuously during the further ball milling,volume fraction of interface becomes higher.Ball-milling leads to an increase in the defect density and free energy in elements Zr and Ni,finally,alloy powder transforms into amorphous state.The result of VSM indicates that Ni7Zr2 amorphous alloy powder exhibits excellent soft magnetic properties.更多还原