Effect of aluminiumon ordering of highly stabilised β-Ti-V-Cr alloys

Abstract

The microstructure of Ti-(20–37)V-15Cr-(0-7)AI (wt-%) alloys has been examined using optical microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray and neutron diffractometry. It has been found that addition of 4 wt-%AI to the Ti- V-Cr ternary system leads to the ordering of the bcc β matrix (A2) into a B2 structure. The order/disorder transition temperature (T_c) was determined by in situ TEM heating of an alloy of Ti-32V-15Cr-5.6 AI to be ∼620°C. The site occupancy of Al and Cr in the B2 was determined by atom location by channelling enhanced microanalysis (ALCHEMI) to be on the V and Ti sites, respectively. The results are discussed in terms of the effects of Al on ordering in the highly stabilised β- Ti- V-Cr-AI alloys.