Microstructure, mechanical properties, electrical resistivity, and corrosion behavior of (AlCr)x(HfMoNbZr)1-x films

Abstract

Refractory high-entropy alloys (RHEAs) have emerged as a new class of materials due to their exceptional properties such as high strength, high-temperature stability, and potential for corrosion resistance. In this study, we investigate the effect of Al and Cr co-alloying on the crystal structure, mechanical properties, electrical resistivity, and corrosion resistance of HfMoNbZr film. (AlCr)x(HfMoNbZr)1-x films were grown using direct current magnetron sputtering, with Al50Cr50 and Hf25Mo25Nb25Zr25 target co-sputtering. Our findings reveal that all films possess a B2-type BCC fine-grained crystallite structure. Moreover, an increase in AlCr content results in an increase in hardness and electrical resistivity, which can be attributed to the stronger directionally angular bonds and higher local lattice distortion caused by Al atoms, as confirmed by density functional theory (DFT) calculations. Additionally, the (AlCr)x(HfMoNbZr)1-x films exhibit excellent corrosion resistance in 3.5 wt% NaCl solution, as indicated by a corrosion current below 10−8 A/cm2. Remarkably, at PAlCr = 90 W, the current density reaches a minimum value of 4.85 ± 0.43 × 10-9 A/cm2. These results demonstrate the tunable properties of RHEAs through element alloying, which offers promising opportunities for various applications.