Ultra-strong lightweight TiAlVSc multi-principal element alloys for elevated temperature applications

Microstructure evolution of the Ti-Al-V-Sc MPEAs with varying Sc content during deformation under various temperatures. • Lightweight TiAlVSc alloys with exceptional high temperature specific strength. • Yield strength remains relatively consistent from room temperature to 900 °C. • Addition of Sc to TiAlV alloys enhances their high temperature strength at 1000 °C. • High temperatures strength due to precipitation strengthening via α 2 precipitates. Lightweight multi-principal element alloys (MPEAs) have received significant attention in aerospace materials research due to their low density and excellent high-temperature performance. Rare earth elements, with their unique thermophysical properties, play a crucial role in enhancing the high-temperature performance of alloys. In this study, the effects of Sc on the microstructure and mechanical properties of Ti 60-x Al 30 V 10 Sc x (x = 0, 3.5, 6.5 at. %) MPEAs at different temperatures were systematically investigated. Contrary to common belief, the strength of the material remains consistent up to 900 °C. The addition of Sc also significantly improves the high-temperature strength of the alloys at 1000 °C, with Sc3.5 and Sc6.5 alloys having high-temperature strengths of 3.3 and 2.6 times compared to the Sc0 alloy. Moreover, the addition of Sc leads to significant changes in the microstructure of the as-cast alloy. The mechanism of the significant enhancement of high-temperature properties by Sc elements is rationalized by the BCC/B2 to α 2 phase transitions during high-temperature deformation. This study demonstrates that Sc can effectively enhance the high temperature strengths of Ti-Al-V-based MPEAs, providing critical experimental insights and theoretical support for high-temperature alloy design.