Mechanisms were considered, for the formation of fault-pairs in the L12 structure, which involved ordinary and super-glide dislocations with co-planar Burgers vectors. These fault-pairs could serve as 2-layer embryonic twins, and twin-thickening could occur via the coalescence of fault-pairs which were located at various levels within a slip band. The crystallography of deformation twins was studied in as-processed TiAl by means of transmission electron microscopy, and was correlated with the slip required for the formation of fault-pairs. The correlations were found to be consistent with the suggestion that fault-pairs were involved in the formation of deformation twins. Slip was observed ahead of a twin which terminated within a crystal.

Formation of Deformation Twins in TiAl. E.Cerreta, S.Mahajan: Acta Materialia, 2001, 49[18], 3803-9