Metastable phase formation during α2(D019) to γ(L10) transformation in as-atomized γ-TiAl alloy powders

alpha(2)(D0(19)) to gamma(L1(0)) transformation during heating of as-atomized gamma-TiAl powder was investigated by differential scanning calorimetry and x-ray diffraction. The as-atomized coarse powder particles (gamma-TiAl powder: Ti-45Al-2Nb-0.7Mo-0.1W-2Cr-0.27O-0.2Si) with large amounts of retained alpha(2) are a perfect candidate to investigate this transformation. It was observed that alpha(2) to gamma transformation is a two-step process involving the formation of a disordered face-centered-cubic gamma(')TiAl [with a(gamma('))=c(gamma)] as an intermediate phase followed by ordering. (C) 2004 American Institute of Physics.