Thermal exposure induced α2+γ→B2(ω) and α2→B2(ω) phase transformations in a high Nb fully lamellar TiAl alloy

As-HIPped Ti-44Al-8Nb-IB was exposed to 700 degreesC air for up to 3000 h. It has been found that the beta phase removed by hot isostatic pressing (HIPping) reforms as ordered B2 with omega phase during parallel decomposition of alpha(2) lamellae to alpha(2) + gamma lamellae and perpendicular decomposition of single alpha(2) laths into alpha(2) short sections, causing phase transformations of alpha(2) + gamma --> B2(omega) and alpha(2) --> B2(omega). (C) 2003 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.