Fabrication of TiAl alloys by MA-PDS process and the mechanical properties

Powders of Ti–50Al and Ti–48Al–2Cr alloys were synthesized through mechanical alloying (MA) and were then sintered and concurrently consolidated by using a pulse discharge sintering (PDS) process. The mechanically alloyed Ti–50Al and Ti–48Al–2Cr powders showed similar X-ray diffraction profiles, corresponding to that of the alpha titanium supersaturated with Al. The TiAl alloys were sintered for a short sintering time of 900 s. The microstructures of these two alloys contains equiaxed gamma TiAl with sub-micron grain size and small amount alpha-2 Ti3Al phase. The alloy with chromium addition showed coarser microstructure and superior mechanical properties to that without additives, at the ambient temperature and at elevated temperatures as well. The fracture strength of the as-sintered Ti–50Al and Ti–48Al–2Cr alloys increased with increasing testing temperature up to about 873 K and a decrease followed up.