用机械合金化方法制备Ni-Al系金属间化合物

用球磨机分别对Ｎｉ－５０ａｔ．－％Ａｌ和Ｎｉ－２５ａｔ．－％Ａｌ混合粉末进行机械合金化，并对Ｎｉ_３Ａｌ预合金粉末进行高能球磨，观察了粉末的金相组织，测定了粉末的硬度、平均直径和晶粒尺寸，并作了ＸＲＤ物相分析结果表明，经３ｈ研磨，Ｎｉ－５０ａｔ．－％Ａｌ混合粉末变成ＮｉＡｌ金属间化合物，其晶粒直径约５ｎｍ；经５ｈ机械球磨，Ｎｉ－２５ａｔ．－％Ａｌ混合粉末成为无序的亚稳定Ｎｉ固溶体，而Ｎｉ_３Ａｌ预合金粉末由Ｌｌ_２型长程有序金属间化合物转变为ｆｃｃ无序固溶体；球磨更长时间，则形成纳米晶．

PREPARATION OF Ni-Al INTERMETALLIC COMPOUNDS BY MECHANICAL ALLOYING

The powder mixtures of Ni and Al with compositions of Ni50 at.-% Al and Ni-25 at.-% Al as well as Ni_3Al alloy powder were milled in a Spex 8000 Mixer/Mill respectively.After 3 h of milling,Ni-50 at.-%Al mixture transforms into NiAl with grain size of about 5 nm,while after 5 h,Ni-25 at.-%Al mixture transforms into disordered metastable Ni solid solution.As to the Ni_3Al alloy powder,5 h milling makes its structure change from Ll_2-type intermetallic compound with long range order into fcc disordered solid solution;further milling results in the formation of nanocrystalline structure.