Intragranular nucleation sites of massive gamma grains in a TiAl-based alloy

Massive gamma grains were generated in a TiAl-based alloy through ice-water quenching from the alpha domain. Apart from those located along alpha(2)/alpha(2) grain boundaries, a few massive gamma grains were detected inside the alpha(2) grains. Some of these intragranular grains were revealed to be attached to particular alpha(2) twins (K-1: "{212103}" eta(1): < 5146 >), in a Blackburn orientation relationship with them. Others were identified as developing in feathery colonies of similar crystallographic orientation. Whatever the nucleation site, further growth of all massive gamma grains involves successive twinning on < 111 >(gamma) planes. (c) 2007 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.