AN IN-SITU STUDY AT ROOM-TEMPERATURE OF DEFORMATION PROCESSES IN A TI23.7AL-9.4NB ALLOY

The microstructure of the Ti-23.7Al-9.4Nb alloy investigated in the pr esent study consists of globular precipitates of an alpha(2) phase emb edded in a matrix of a beta(2) phase. Deformation processes in this al loy have been investigated by in situ deformation experiments performe d at room temperature. Glide of dislocations has been observed on diff erent planes in the two phases. The corresponding deformation mechanis ms have been determined. Sources, multiplication processes, and disloc ation transmission at the interfaces have been observed and analysed i n detail. The propagation processes of microcracks and the faces of mi cro-cracks have been characterized. A scenario for the plastic deforma tion involving all these elementary processes is proposed and the role of niobium for the ductility improvement of the alloy is discussed. C opyright (C) 1996 Elsevier Science Ltd