Development and characterization of a low-density TiNbZrAlTa refractory high entropy alloy with enhanced compressive strength and plasticity

A new refractory high entropy alloy (RHEA) is designed by combining refractory elements Nb and Ta with Ti, Zr, and Al, resulting in a (TiNbZr)89(AlTa)11 alloy composition with a low-density of 6.0 g/cm3. The novel RHEA features a BCC matrix with B2 and Zr5Al3 nano precipitates, exhibiting a compressive yield strength of ∼890 MPa and specific yield strength of ∼148.3 MPa g−1 cm3. Remarkably, the alloy demonstrates excellent compressive plasticity of ∼70% at 298 K. As the temperature increases to 873 K, 1073 K, and 1273 K, the yield strength of the RHEA gradually decreases to ∼610 MPa, ∼ 210 MPa, and ∼ 60 MPa, respectively. These results indicate that this novel RHEA showcases a combination of good specific strength and plasticity. Post-compression, B2, and Zr5Al3 phases are observed. The second-phase particles dispersed throughout the grains hinder dislocation motion and contribute to the formation of sub-grain boundaries during hot compression.