Nanoscale origins of the oriented precipitation of Ti₃Al in Ti[Formula presented]Al systems

Oriented precipitation of Ti₃Al in [Formula presented] alloys has been already proposed, however the underlying physical mechanism behind the specific precipitation behavior is still unclear. Here, we report that the origin is preferred formation of stacking faults on prismatic planes. In other words, stacking faults induced by Al alloying act as nucleation sources for the precipitation of Ti₃Al phases, and their particularly spatial distributions assist in “orienting” Ti₃Al precipitates (oriented precipitation). These findings enrich current understanding of nanoscale precipitation behavior, and provide the inspiration of controlling the precipitation behavior by tailoring the physical type and spatial distribution of defects.