Influence of strain rate and grain size on TiAl intermetallics ductility at room temperature

Stoichiometric intermetallic compound TiAl and a number of alloys on its base (Ti-34 mass.% Al; Ti-34Al-4; Ti-34Al-23.5Ta, Ti-34Al-4Hf; Ti-34Al-1Cr; Ti-34Al-4-0.05B) with various grain size were studied for their tensile properties depending on strain rate in the range of 1.3x10-4-8x101 s-1. The ductility of TiAl is revealed to vary essentially with strain rate and reaches its peak in the range of 10-2-100 s-1. With a grain size decrease the growth of optimal strain rate corresponding to maximal ductility is observed. it is shown that the dependence of intermetallics behaviour on grain size and strain rate is conditioned by competing development of slip and mechanical twinning as well as dislocation twinning. 33 refs., 6 figs., 2 tabs