Akira Terayama

Fabrication of TiNi Powder by Mechanical Alloying and Its Shape Memory Characteristics of Sintered Alloy

This paper presents the fabrication condition of the TiNi alloy powder by mechanical alloying and its shape memory characteristics of the sintered alloy. The effect of mechanical alloying condition on the characteristics of mechanically alloyed powder (MA powder) was investigated. Also, the difference in sintering behavior between the MA powder and the mixed elemental powders by V-blender and the microstructure, shape memory characteristics of the sintered alloys were also examined. The MA powder was fabricated by milling using a planetary ball mill in rotational speed from 200 rpm to 500 rpm for various milling times in an atmosphere of Ar gas. These two types of powders prepared in different processes were sintered by a pulse-current pressure sintering equipment at various sintering temperatures. The powder agglomerated and its particle size became larger with an increase in milling time. The mixture of Ti and Ni powders changed into an amorphous state by processing for 3.6 ks over 300 rpm. The alloy sintered by the MA powder showed more uniform phase of TiNi than that by the mixed elemental powders sintered in a same manner, however, the former showed a lower density than the later due to a larger particle size of its MA powder of before-sintering.