Observations of [100] dislocations in ¹/₂[112] reacted dislocation networks in lamellar TiAl subboundaries

Abstract

Dislocations with Burgers vectors b given by b = [100] have been observed as products of a reaction occurring between dislocations with b=½〈112] gliding on inclined {111} planes in lamellar Ti-50at.% Al. This reaction may be described as ½[112](111)+¹/₂[112](111) = [100] and is the most energetically favourable of all possible reactions in the TiAl system. The reaction product is presumably sessile. The origin of these defects may be associated with the thickening on thinning of laths of Ti₃Al during initial processing and/or subsequent heat treatment of the material.