He-ion Irradiation Effects on the Microstructures and Mechanical Properties of the Ti-Zr-Hf-V-Ta Low-Activation High-Entropy Alloys.

Abstract

High-entropy alloys (HEAs) have shown promising potential applications in advanced reactors due to the outstanding mechanical properties and irradiation tolerance at elevated temperatures. In this work, the novel low-activation Ti2ZrHfxV0.5Ta0.2 HEAs were designed and prepared to explore high-performance HEAs under irradiation. The microstructures and mechanical properties of the Ti2ZrHfxV0.5Ta0.2 HEAs before and after irradiation were investigated. The results showed that the unirradiated Ti2ZrHfxV0.5Ta0.2 HEAs displayed a single-phase BCC structure. The yield strength of the Ti2ZrHfxV0.5Ta0.2 HEAs increased gradually with the increase of Hf content without decreasing the plasticity at room and elevated temperatures. After irradiation, no obvious radiation-induced segregations or precipitations were found in the transmission electron microscope results of the representative Ti2ZrHfV0.5Ta0.2 HEA. The size and number density of the He bubbles in the Ti2ZrHfV0.5Ta0.2 HEA increased with the improvement of fluence at 1023 K. At the fluences of 1 × 1016 and 3 × 1016 ions/cm2, the irradiation hardening fractions of the Ti2ZrHfV0.5Ta0.2 HEA were 17.7% and 34.1%, respectively, which were lower than those of most reported conventional low-activation materials at similar He ion irradiation fluences. The Ti2ZrHfV0.5Ta0.2 HEA showed good comprehensive mechanical properties, structural stability, and irradiation hardening resistance at elevated temperatures, making it a promising structural material candidate for advanced nuclear energy systems.