Twin intersection in tensile deformed -TiAl intermetallic compounds

Sawai, Tomotsugu; Hishinuma, Akimichi

TiAl intermetallic compounds are potential materials for high temperature structural applications. They have also low induced radio-activity and good radiation resistance, which make these alloys very attractive in nuclear applications. Their ductility at low temperatures should be, however, still improved and their deformation mechanism is of great concern. In this study, intersections of deformation twins in -TiAl grains were examined in Ti-47at%Al alloy specimens tensile-tested at 873 K. Transmission electron microscopy (TEM) revealed 1/2110]{111} ordinary-type dislocations and 1/6112]{111} twins in deformed -TiAl grains. Some -TiAl grains contained twins on two different {111} planes, which intersect along 110] directions (type-1). No twin intersection along 101] (type-2) was observed, which was often reported in compressed specimens. Results are discussed with the Schmid factor distributions of twinning systems and ordinary slip systems as the function of tensile directions.