Deformation mechanism in laser-powder bed fused Ti-6Al-2Sn-4Zr-2Mo alloy: Role of heat treatment

The deformation mechanisms of heat-treated laser powder bed fused Ti-6Al-2Sn-4Zr-2Mo were investigated using tensile testing and transmission electron microscopy. Heat-treated conditions (solutionized and solutionized + aged) showed improved ductility and non-monotonic strain-hardening behavior compared to the as-built state. Transmission electron microscopy analysis revealed the formation of a metastable β phase (β _m ) with a molybdenum equivalent content below 8 wt.%, which promotes stress-induced martensitic (α′) transformation during deformation. This transformation enhances strain hardening and delays necking. The solutionized + aged condition exhibited lower β-phase stability and a greater tendency for martensitic transformation. These results highlight the critical role of β-phase metastability in governing deformation and strength-ductility synergy.