Correlation of amorphization effects in titanium solid solutions via mechanical milling and annealing

Powders of titanium solid solutions were amorphized completely via mechanic al milling. Bulk samples of bcc titanium solid solution were also partially amorphized through low-temperature annealing. The reference alloy Ti65Cr13 Cu16Mn4Fe2 requires the shortest milling time to achieve complete amorphiza tion. A strong dependence of critical milling time for complete amorphizati on on alloy composition is found near the reference alloy. Meanwhile, the r eference alloy is also the easiest to amorphize partially by annealing. The strong correlation of amorphization effects observed is consistent with th e mechanism where the formation of amorphous areas is dependent on the size of the free-energy gap Delta G(c-->a) between the crystalline phase and th e amorphous phase and on how easily this gap can be closed. The smaller the free-energy gap Delta G(c-->a) of the solid solution, the less milling is required for complete amorphization, and the more favourable amorphization by annealing becomes.