Effect of Ni on Amorphization of Ti-Cu-Ni Ternary alloys Prepared by Mechanical alloying

Amorphous alloys has been taken into consideration because of their unique properties and are nominated as the future engineering materials. In this research, the effect of Ni and milling time on amorphization process and thermal stability of Ti۵۰Cu۵۰-xNix(x=۱۰, ۱۵, ۲۵ at%) alloy system were investigated. The evolution of amorphization during milling, thermal stability and subsequent heat treatment were evaluated by x-ray diffraction (XRD) and differential scanning calorimetry (DSC). The results showed that alloys reached to the highest content of amorphous phase in Ti۵۰Cu۴۰Ni۱۰, Ti۵۰Cu۱۵Ni۳۵ and Ti۵۰Cu۲۵Ni۲۵ alloy compounds after ۶۰, ۴۰ and ۱۰ hours respectively. Differential scanning calorimetry showed thermal stability of amorphous alloy, exhibiting a distinct glass transition and crystallization temperature and a wide supercooled liquid region for Ti۵۰Cu۲۵Ni۲۵ powder alloy with a value about ۴۵ k. Heating Ti۵۰Cu۲۵Ni۲۵ amorphous alloy at ۹۴۳ k for ۱۰ min results in the formation of intermetallics such as CuTi and NiTi۲ phases. In addition, mechanical properties of amorphous powders were studied by Vickers microhardness test. The alloy with ۲۵ percent Ni showed The high value of hardness about ۸۸۴ Hv after ۴۰ hours milling.

Keywords:

Amorphization , Thermal stability , Glass Transition , Crystallization , Supercooled