Abstract:The microstructure,alloying reaction and sintering behavior of the powder produced by Mechanical Al- loying(MA)for 8 h from 64 wt.-% Ti powder and 36 wt.-% Al powder were studied by scanning electron microscopy,optical microscopy,X-ray diffractometry,differential scanning calorimetry(DSC)and dilatometry. The mechanically alloyed powder partictes are Ti-Al composite particles.Thus,titanium aluminides can form easily in the powder through diffusion during heat treatment.It is shown that the sintering behavior of this pow- der,different from the behaviors of TiAl alloy powder and mixed powder of 64 wt.-% Ti powder and 36 wt.-% Al powder,changes from expansion at temperatures below 1000℃ to shrinkage at temperatures above 1000℃. Homogeneously alloyed TiAl material with a density over 96% of the theoretical density can be produced from the mechanically alloyed powder by compaction-sintering.

Key words: TiAl alloy powder; mechanical alloying; SEM; optical microscopy; DSC; dilatometry