Correlation of amorphization effects in titanium solid solutions via mechanical milling and annealing
Powders of titanium solid solutions were amorphized completely via mechanical milling. Bulk samples of bcc titanium solid solution were also partially amorphized through low-temperature annealing. The reference alloy Ti 65 Cr 13 Cu 16 Mn 4 Fe 2 requires the shortest milling time to achieve complete amorphization. A strong dependence of critical milling time for complete amorphization on alloy composition is found near the reference alloy. Meanwhile, the reference alloy is also the easiest to amorphize partially by annealing. The strong correlation of amorphization effects observed is consistent with the mechanism where the formation of amorphous areas is dependent on the size of the free-energy gap ΔG c→a between the crystalline phase and the amorphous phase and on how easily this gap can be closed. The smaller the free-energy gap ΔG c→a of the solid solution, the less milling is required for complete amorphization, and the more favourable amorphization by annealing becomes.