Consolidation at Low Heat in Mechanically Alloyed Ti-Al Powders

Abstract

Mechanical alloying (MA) of Ti-48mol%Al powder mixtures was performed for relatively short milling times (10.8-86.4ks) by planetary ball mill. The MA powders were hot-pressed at relatively low temperatures (673-873K) and pressures (200-600MPa). The influence of hot press temperature and pressure on consolidation (densification, reactive synthesis, etc.) in the MA powders was investigated. In this experiment, some non-reactive Ti powders remained in the consolidated materials, but the optimum hot press conditions for consolidation by reactive sintering were determined by the MA conditions (milling duration, etc.). Subsequently, the hot-pressed specimens were tested for hot-working by compressive creep testing at 1273K and initial pressure of 50MPa. The hot workability was excellent for superplasticity-like deformation. The densification and alloying did not alter the ultra-fine grain size, and the highest density and greatest change in density by hot-working was obtained by the powders milled for longest time.