DISLOCATION DYNAMICS IN CARBON-DOPED TITANIUM ALUMINIDE ALLOYS

Different thermal treatments were conducted on carbon containing two-p hase titanium aluminide alloys to obtain solid solution and precipitat ion hardening effects. The strengthening mechanisms were characterized by activation parameters of the glide processes and electron microsco pe observations. Carbon in solid solution was found to be less efficie nt than carbide precipitates for hardening the material. Fine dispersi ons of Ti3AlC perovskite precipitates form arrays of strong glide obst acles so that perfect and twinning partial dislocations were effective ly pinned. This mechanism results in a high athermal contribution to t he flow stress, which significantly improves the high temperature stre ngth of the material. (C) 1997 Elsevier Science S.A.