Effects of Transient Thermal Shock on the Microstructure and Corrosion Properties of a Reduced Activation High-Entropy Alloy

Due to the extremely harsh environment in the fusion reaction, the device often faces transient thermal shocks (TTS), which would inevitably cause significant effects on the microstructures and performance of the structural materials. In this study, a reduced activation VCrFeTa 0.2 W 0.2 high-entropy alloy (HEA) was developed by vacuum arc melting, then the effects of TTS by electron beams on its microstructure, hardness and corrosion properties were investigated. TTS did not change the phase composition of the alloy, but the volume fraction of each phase changed. Microhardness increased from 673 HV to 714 HV and 736 HV with the TTS power enhanced, respectively. Meanwhile, it's found that this reduced activation HEA after TTS exhibits a low corrosion current density of ~ 0.472 μA/cm 2 in a 3.5 wt.% NaCl solution, which is about a third of that in the as-cast one. The pitting potential of the VCrFeTa 0.2 W 0.2 HEA after TTS was 1.165 V SCE and 1.112 V SCE , which is much higher than that of the as-cast one. A refined composite multiscale entropy method is utilized to analyze the influence of TTS on current fluctuation distribution in the corrosion process