Effects of microalloying and ceramic particulates on mechanical properties of TiAl-based alloys

Micro-alloyed titanium aluminides and TiAl-based composite with a fully dense structure have been synthesized by a powder metallurgical method. X-ray diffraction and EDX studies show that the monolithic TiAl-based alloy and its composite consist of TiAl and Ti₃Al compounds with the former as the major phase. Additions of Nb and/or (Mo + Cr) exert remarkable effects on the resultant phase compositions and mechanical properties of TiAl-based alloys. Both the added Mo and Cr elements are dissolved into the TiAl-based compounds to exhibit solid solution strengthening effect whereas Nb is only partially dissolved and the rest appears in the Nb-rich compound, Nb₂Al. In general, the micro-alloyed TiAl and the composite exhibit superior flexural strength and fracture toughness to TiAl-based monolithic compound.