ω-phase formation in V[sbnd]Al and Ti[sbnd]Al[sbnd]V alloys

Abstract

ω-phase formation in V-50 at.% A1 alloy and Ti[sbnd]Al[sbnd]V alloys has been studied using electron diffraction. It is shown that both electron and size factors are important in affecting the magnitude of the deviation of diffuse ω maxima from the commensurate ω maxima positions. It is suggested that the addition of the electron-deficient element Al to the later transition metal V will destabilize the high-temperature β-phase and favour ω formation. It is expected by analogy that the w transformation may occur in other later transition-metal based alloy systems such as Nb[sbnd]Al, Mo[sbnd]Al, Cr[sbnd]Al and Mn[sbnd]Al. Structural models have been proposed to interpret the heavy streaking effects in β + ω and B2 + ω structures.