TEM observations of twin intersections in a Ti–47Al–2Cr–2Nb–0.1Y alloy compressed at room temperature

Twin intersections in TiAl alloy compressed at room temperature were investigated by high-resolution electron microscopy (HREM). One incident twin (TI) was observ -d to divide into three thin twin bands and leave several superlattice intrinsic stacking faults (SISFs) in the barrier twin (TB). It was a process related. to the dislocation dissociation: (1/2)[112] -> (1/6)[112] + SISF + (1/6)[112] + SESF + (1/6)[112]. The nucleation of type-I twin intersection was also observed. The incident twin was found to be a bundle of SISFs, instead of a perfect twin lath. In addition, a triangular striated structure around type-I twin intersection was examined by HREM. The formation mechanism of this triangular striated structure and the related dislocation reactions were discussed. (c) 2007 Elsevier B.V. All rights reserved.