Influence of Fe on the microstructure, superplasticity and room-temperature mechanical properties of Ti–4Al–3Mo–1V-0.1B alloy

Decreasing the superplastic forming temperature of Ti alloys is currently an important issue. This study investigated the impact of modifying the Ti–Al–Mo–V alloy with different percentages of Fe (0–2 wt.%) on the microstructure, superplasticity and post-forming mechanical properties. The results revealed that during superplastic deformation, the increase in Fe content facilitated the recrystallisation and fragmentation of the phases and grain boundary sliding due to the accelerating diffusivity by Fe. In contrast, the presence of Fe increased the susceptibility to grain growth. A high strain rate sensitivity coefficient m (0.45–0.5) and maximum elongation to failure (500–1000%) were achieved for these alloys at a constant strain rate of 1 × 10−3 s−1 and in a low temperature range (625–775 °C). Alloying the investigated alloy with Fe increased the post-forming room-temperature tensile strength by 90–220 MPa and decreased the ductility by 1–2%. Alloying with 0.5% Fe provided a good combination of the superplastic and room-temperature mechanical properties for the studied alloys. •0.5-2 wt%Fe addition substantially improved the superplasticity of Ti-based alloy.•Fe facilitated the recrystallisation/fragmentation.•Alloying with Fe accelerated grain growth in Ti-based alloy.•Fe alloying increased the post-forming room-temperature tensile strength.•0.5%Fe provided a good combination of the superplastic and mechanical properties.