机械合金化制备W-Ni-Fe纳米-非晶材料

Synthesis of W-Ni-Fe Nanostructured and Amorphous Materials by Mechanical Alloying

按照80.7W-13.2Ni-6.1Fe的原子分数,采用机械合金化(MA)方法,制备了W-Ni-Fe合金纳米晶和非晶相的混晶结构。结合XRD,利用近似内标法计算了球磨不同时间球磨粉中残留晶体W的体积分数和非晶相中的W含量,并分析了球磨过程中非晶形成的机制。结果表明:随球磨时间的延长,W晶粒不断细化,球磨60h,钨晶粒尺寸可达到10nm^20nm,非晶相的形成过程主要是Ni(Fe)首先溶入W中形成过饱和固溶体,球磨20h后形成W-Ni(Fe)非晶。过饱和固溶体的形成是由于携带较大晶界存储能的小粒子不断溶入W中,计算得到可固溶的临界Ni粒子尺寸约为3nm。由于Fe污染不断溶入W中,在球磨过程中,残留晶体W的体积分数不断减少,而非晶相中的W-Ni(Fe)比例基本保持恒定,为63W-37Ni(Fe)。

80.7W-13.2Ni-6.1Fe (atom percent) tungsten heavy alloys were prepared by mechanical alloying (MA). The volume fraction of the remanent crystalline W in the as-milled materials and the W atom percent in amorphous phase were measured using a method similar to the internal standard method and the route of amorphization. The mechanism of the amorphous phase forming in the process of milling was analyzed. The results show that the crystalline size of tungsten reaches 11 nm similar to 20 mn after milling for 60 h. Ni dissolves in crystalline W and then amorphization of W supersaturated solid solution occurs after milling for 20 h. Forming of the supersaturated solid solution is attributed to dissolving of the small particles with large stored energy into W continuously and the critical size of the Ni particles which can dissolve in the W is 3nm calculated based on the stored energy model. During milling, the volume fraction of the remanent crystalling W is decreased, and the W contents in the amorphous phase remain content, approximately 63W-37Ni(Fe), due to the Fe contamination dissolving into W continuously.