Study on ω-assisted α nucleation behavior of metastable β-Ti alloys from phase transformation mechanism

Abstract

The nucleation mechanism of ω-assisted α phase and the selection of α variants during isothermal aging of Ti-15Mo alloy were studied. The results show that α phase preferentially nucleates at the ω/β interface. The β→ω→α phase transition is affected by the long-range diffusion of solute atoms, involving lattice reconstruction and Mo diffusion. Due to the adaptive regulation of α variant, (0001)α1,2,3 and (011̅0)α1,2,3 variant were observed in the sample aged at 450 °C for 180 h. The orientation relationship between β matrix and α variants is as follows:<111>β∥<21̅1̅0>α, {110}β∥{0001}α.