Interactions between dislocations and twins in deformed titanium aluminide crystals

Abstract

Using scanning, transmission electron microscopy and aberration-corrected scanning transmission electron microscopy, we have studied the interactions between dislocations and twins in impact deformed polysynthetic twinned TiAl crystal. The 1/3 < 11¯1¯] and 1/6 < 211] step dislocations on coherent twin boundaries reveal the interactions of glissile 1/2 < 101> dislocations with the coherent twin boundaries. An abnormal stacking fault was found adjacent to the coherent twin boundary. It has the same stacking sequence but different atom species in the [1¯10] direction with an additional displacement of 1/4[1¯10] in two neighboring {111} layers, and is likely induced by the slip of a 1/12[112] (i.e. 1/4[1¯10] + 1/6[21¯1]) dislocation.