Microstructure and mechanical properties of the new TiZrHfReAl HCP high entropy alloy

ABSTRACT

In the present study, the intelligent addition of Re and Al to TiZrHf equiatomic ternary alloy resulted in a new single-phase Ti₃₀Zr₃₀Hf₃₀Re₅Al₅ HCP high entropy alloy. The XRD analyses show that the TiZrHfRe_x alloys have a single-phase HCP structure until x = 5 at.%. Subsequently, the TiZrHfRe₅ retains its single-phase HCP microstructure with the addition of Al upto 5 at.%, leading to a new quinary TiZrHfRe₅Al₅ HCP HEA. Microstructural investigations using SEM revealed the formation of compositionally homogeneous single-phase HCP solid solution for TiZrHf, TiZrHfRe₅ and TiZrHfRe₅Al₅ alloys. Vicker's microindentation measurements revealed that adding Re, followed by Al, increases the hardness of the TiZrHf ternary alloy from 7.85$\pm$0.37–8.35$\pm$0.42 GPa. In a nutshell, a novel quinary HCP alloy was developed based on transition metals, allowing HCP HEA compositional space to expand beyond rare-earth (RE) based HEAs.

KEYWORDS:

• High entropy alloys
• hexagonal close-packing
• microindentation
• solid solution strengthening

Disclosure statement

No potential conflict of interest was reported by the author(s).