Solid-state phase transformation-induced heterogeneous duplex structure in Ti–Sn–Fe alloys

Systematic microstructural investigations reveal that heterogeneous duplex structure in Ti–Sn and Ti–Sn–Fe alloys consisting of an array of Ti3Sn plates surrounding the duplex colony and ultrafine twin results from solid-state decomposition of supersaturated β-Ti into α-Ti + Ti3Sn phases. Moreover, small addition of Fe into the Ti82Sn18 duplex alloy has a strong influence to refine the twinning in the Ti3Sn phase and interlayer spacing of the duplex structure. Such microstructural heterogeneities are effective to enhance both strength and plasticity at room temperature. Based on these results, it is possible to design the unique ultrafine duplex structure with high strength and large plasticity together by introducing the solid-state phase transformation-induced heterogeneity.

► Formation of ultrafine duplex structure in Ti–Sn–Fe alloys via solid-state phase transformation.
► The addition of Fe is effective to introduce the refinement of twins upon solidification.
► The refinement of twin at the Ti3Sn phase plays a crucial role to enhance the mechanical properties.