New lightweight and super-hard refractory high-entropy alloys developed by a high-throughput method

Lightweight refractory high-entropy alloy (LRHEA) is one of potential structural materials in aerospace industry for its excellent high-temperature comprehensive properties and low density. In this work, a new high-throughput method to develop LRHEAs was proposed. The equimolar HfNbTaTiZr alloy was immersed with melting pure aluminum for a given time, and a thick layer with composition gradient was obtained. Further characterizations of the layer result in relations between composition and nanohardness or Young's modulus, which facilitate the selection of the optimal composition with desired properties. Finally, three LRHEAs were designed and casted into bulk samples with arc-melting method. The alloys show superhigh Vickers hardness of 8.29–9.56 GPa and low densities of 6.27–7.08 g/cm3, showing great potentials in applications as wear-resistant materials. The high-throughput method developed here may also accelerate the development of new LRHEAs.