Nanoscale origins of the oriented precipitation of Ti3Al in TiAl systems

Oriented precipitation of Ti3Al in TiAl 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.

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