Studies on high-temperature stability and strengthening mechanisms of high/medium-entropy alloys for potential nuclear applications: The case of FeCrV-based alloys

High-temperature stability and strengthening mechanisms of high/medium-entropy alloys (HEAs/MEAs) have been studied for Ti-added FeCrV-based MEAs. Experimental results show that FeCrVTix MEAs can maintain good high-temperature stability in chemical element, phase structure and mechanical property. A mixed-strengthening-mechanism model dominated by precipitation and fine-grain strengthening has been proposed by comparing experimental results and model calculations of the yield strength increments for the FeCrV-based MEAs owing to Ti addition. The calculated strength increments with this mixed-strengthening-mechanism model closely match the series experimental results. The excellent compressive fracture strain in the FeCrVTix MEAs mainly comes from crack tip plasticity, and Ti addition not only enhances compressive strain by grain refine-ment, but also improves compressive strain by crack deflection and bridging. Based on this strengthening model, the content, size and distribution of precipitates can be designed and controlled to regulate and optimize the mechanical properties of HEAs/MEAs. Therefore, this study provides new approaches and ideas for the design and development of HEAs/MEAs with high strength and good ductility for advanced nuclear energy systems.