THEORETICAL INVESTIGATION OF DUCTILIZING EFFECTS OF ALLOYING ELEMENTSON TIAL

In this paper, the electronic structure of ternary TiAl-based alloys w as calculated by using the discrete variational Xa cluster method. Fro m the calculations, three parameters, the bond strength, the anisotrop y of bond strength and the resistance of the lattice to dislocation mo tion, were defined to investigate the effects of alloying elements on the ductility of TiAl. The results of calculation show that the resist ance of the lattice to dislocation motion is increased by most alloyin g elements, resulting in an increase of the yield strength of the allo yed compounds. The alloying elements Sc, V, Cr, Mn, Zr, Nb and Mo redu ce the resistance of the lattice to 1/2<110] ordinary dislocations rel ative to <011] superdislocations. The relevance of these results to th e ductilization of TiAl is discussed. (C) 1997 Elsevier Science Limite d.