Interactions between dislocations and twins in deformed titanium aluminide crystals

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 < 1<(11)over bar>] 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) over bar 10] direction with an additional displacement of 1/4[(1) over bar 10] in two neighboring {111} layers, and is likely induced by the slip of a 1/12[112] (i.e. 1/4[(1) over bar 10] + 1/6[2 (1) over bar1]) dislocation. (C) 2018 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.