Superior high-temperature strength induced by solid solution strengthening in light-weight refractory high entropy alloy

Refractory high entropy alloys (RHEAs) have a high melting point and strength, exhibiting great potential for high-temperature applications. In this work, a novel single-phase Ti60(AlVCr)28Mo12 RHEA with a low density of 5.3 g/cm3 is reported, exhibiting a high strength and plasticity at room and elevated temperatures. The singlephase RHEA has a high yield strength of 760 MPa with a significant strain hardening capability at 600 degrees C and remains 530 MPa as the temperature increases to 800 degrees C, which is twice as high as dual-phase Ti60(AlVCr)40 RHEA. Mo element has effectively stabilized the high-entropy BCC solid solution phase, inhibiting the formation of ordered precipitates in the matrix phase. The severe lattice distortion increases the dislocation movement barrier and thereby promotes the dislocation multiplication during high-temperature plastic deformation, resulting in significant strain hardening. The strong solid solution strengthening originating from large modulus mismatch is mainly responsible for the enhanced high-temperature softening resistance.