Tuning to more compressible phase in TiZrHfNb high entropy alloy by pressure

Abstract

In this work, the starting nominal Ti25Zr25Hf25Nb25 high entropy alloy (HEA) has two body centered cubic (BCC) phases with a volume percentage about 100:1, with the primary phase having a much larger bulk modulus (incompressible) than the uniform single-phase HEA. We found that these two phases merged into one single BCC phase at pressures beyond 36 GPa, whose bulk modulus dropped to that of the normal homogeneous HEA. After decompressing, the new phase can be sustained to ambient conditions. This abnormal pressure-induced softening was largely related to the lattice distortion evolution and interfacial energy during compression.