Enhanced creep resistance of Ti30Al25Zr25Nb20 high-entropy alloy at room temperature

Abstract

Several previous studies have shown that the dissolution of Al in a solid solution single phase BCC is high unfavorable in TiZrNb system. In this work, a novel Ti30Al25Zr25Nb20 high-entropy alloy (HEA) with a single body-centered cubic (bcc) structure was developed. The Young's modulus and nano-hardness of this HEA measured by continuous stiffness measurement (CSM) technique were 158.2 ± 5.2 GPa and 8.9 ± 0.2 GPa, respectively. The creep behaviors of this HEA at a constant temperature of 20 °C under different loading rates and peak loads were studied by nano-indentation technique. The result indicated that with the increase of loading rates and peak loads, the creep displacement increased, but the creep strain rate sensitive index first decreased and then increased, and the physical mechanisms are interrupted by introducing dislocation activation volume. The reason might attribute to the hysteresis diffusion effect. Compared with other metallic structural materials, Ti30Al25Zr25Nb20 HEA possesses a relatively high dislocation activation volume and low creep strain rate sensitive index value, indicating a significantly high creep resistance.