Production of Mechanically Alloyed Amorphous TiAl Powder by Rotating-arm Reaction Ball Mill with a Control System of Water Cooling

Abstract

In order to realize a high quality and effecient mass production of amorphous TiAI powder, we developed a rotating-arm reaction ball mill having a control system of water cooling, with which one can control a rate of solid state amorphization by the mechanical alloying(MA) of powder mixture, TiAI on the basis of kinetics. It is found that MA of TiAI shows one-stage amorphization with Johnson-Mehl-Avrami exponent of 2.5 at a higher plateau attrition temperature above 69°C, and two-stage amorphization with n₁=1.5 and n₂=3, 2.5 at a lower temperature region. When using a relatively lower water temperature of 5°C, we can obtain mechanically alloyed amorphous TiAl with a sharp crystallization peak and well-defined glass transition, and realize a reduction of milling time to less than 10 hours by decreasing water flow rate:i.e., increasing plateau temperature.