Corrosion Behavior and Mechanism of Spark Plasma Sintered and Arc‐Melted MoNbTaW Refractory High‐Entropy Alloys in Molten Cerium

Refractory high‐entropy alloys (RHEAs) show promising prospects in nuclear applications due to outstanding radiation tolerance, mechanical performance and corrosion resistance. In this study, MoNbTaW RHEA was synthesized via spark plasma sintering (SPS) at 2200°C, while the alloy with identical composition prepared via arc melting served as the control. The two alloys were first systematically characterized for microstructure, densification, grain size and phase constitution, followed by static immersion corrosion testing in molten cerium at 1400°C for 10 h, as well as systematic testing of their room‐temperature mechanical properties. The results reveal that Ta and W possess higher corrosion resistance than Mo and Nb. Benefiting from refined grains and homogeneous microstructure, the SPS alloy achieves better corrosion resistance and mechanical performance, with a mass loss rate of 3.57%, a corrosion rate of 2.72 μm/h, a Vickers hardness of 570.8 HV and a compressive strength of 2585 MPa.