机械合金化合成Invar合金纳米晶粉体

Invar alloy nanocrystalline powders prepared by mechanical alloying

采用商用FeNi30及FeNi50合金粉为原料通过机械合金化（MA）合成纳米晶Invar合金（FeNi36）粉体，研究了不同球磨时间的Invar合金粉体的物相组成、显微组织结构与形貌特征，探讨其合金化机制。结果表明：球磨初期（5—10h），微锻造和冷焊过程使合金粉体呈扁平形复合层状结构，同时FeNi50中的Ni原子逐渐向FeNi30中扩散，发生成分均匀化；球磨40h后，已形成了成分均匀的α＇-Fe（Ni）固溶体，其平均晶粒尺寸约为12nm。此时，机械合金化合成的Invar合金粉体呈球形，表面光滑，继续球磨，大颗粒粉体表面出现裂纹，并碎裂，导致粉体细化。

Nanocrystalline Invar alloy （FeNi36） powders were prepared by mechanical alloying （MA） technique using commercial FeNi30 and FeNi50 alloy powders as raw materials. The phases, mierostructure and morphologies of the Invar alloy powders after milled for different time were studied by XRD, SEM and EDS, respectively. Alloying mechanism of the alloy powders was also discussed. The results show that at the initial milling stage （5 -10 h） , the alloy powders are fiat lamellar composites due to the micro-forging and cold- welding process. The Ni atom diffuses from the FeNi50 alloy powders into the FeNi30 alloy powders to accelerate the composition homogenization of the Invar alloy powders. After milling for 40 h, a homogeneous ct＇-Fe（Ni） solid solution with an average grain size of about 12 nm in the powders forms and the mechanically alloyed Invar alloy powders are spherical and smooth. As the milling time increased, some big particles turn to break and fragment, leading to the refinement of the Invar alloy powders.