Cyclic crystalline–amorphous transformations of mechanically alloyed Co75Ti25

Abstract

We have found that a cyclic crystalline–amorphous phase transformation can occur in Co75Ti25 alloy powder when subjected to ball milling. The results have shown that a single amorphous phase of Co75Ti25 is obtained after 11 ks of mechanical alloying (MA) time. This amorphous phase transforms into a new metastable phase of bcc-Co3Ti upon milling for 86 ks. The bcc-Co3Ti is thermally stable and does not transform to any other phase(s) upon heating up to 1300 K. It however returns to the same amorphous phase of Co75Ti25 upon milling for 360 ks. Further milling leads to the formation of crystalline and/or amorphous phases depending on the MA time.