ω-Assisted α nucleation in a metastable β titanium alloy

We investigate mechanisms of omega-assisted alpha nucleation for microstructure refinement in a metastable beta titanium alloy, Ti-20V (wt%). In particular, we analyze quantitatively the individual and combined effects of concentration and stress fields associated with a growing isothermal omega precipitate and the potency of the omega/beta interface on the activation energy barrier for alpha nucleation as a function of the omega precipitate size and coherency state. We find that the complex interplay among these three factors determines the most potent omega particle size for inducing alpha nucleation and the most favorable nucleation site. (C) 2019 Acta Materialia Inc Published by Elsevier Ltd. All rights reserved.