SEM Observation on Solid State Amorphization of Ni–Nb Alloy by Ball Milling

Abstract

The main purpose of this work is to investigate the mechanism of solid state amorphization by mechanical alloying of Ni–Nb alloy. The solid state amorphization process of a Ni–Nb mixture powder by mechanical alloying was studied by means of the SEM observation and DTA measurement. The solid state amorphization reaction proceeds through the alternating two steps. In the first step, a lamellar structure is formed by kneading introducing many defects. In the second step, diffusion occurs through the defects, using the collision energy of balls. Then the elements are distributed uniformly, forming an amorphous structure simultaneously in the lamellar region. When the whole crystalline structure changes to an amorphous structure, the solid state amorphization reaction is complete.