Dislocation evolution with creep strain and dislocation emission related with alpha(2)-phase dissolution

Abstract

Microstructural evolution of the lamellar structured Ti-46.6Al-1.4Mn-2Mo (at.%) alloy (made by elemental powder metallurgy, EPM) during primary creep deformation under the condition of 800 degrees C/200 MPa is investigated using transmission electron microscopy (TEM). As the primary creep deformation is progressing, the density of the initial dislocation is found to decrease very significantly. Two kinds of dislocation generation modes related to the lamellar interfaces were observed; cross slip and bowing of the interfacial dislocations. And it is suggested that the applied stress play a significant role in the dissolution of alpha(2)-phase, and the interfacial dislocation emission and dissolution of alpha(2)-phase are closely related with each other in controlling creep deformation rate. (C) 1997 Elsevier Science S.A.