Radiation effects on microstructure and hardening behavior in high-entropy fiber strengthened Al-based alloy

High-entropy alloys (HEAs) are promising structural materials for space reactors due to their exceptional mechanical properties and irradiation resistance. However, the high weight and maintenance costs associated with conventional Fe-based HEAs limit their practical use. In this study, a novel high-entropy fiber (HEF)-strengthened aluminum alloy, Al₉₆(NiCoFeCr)₄, was developed by incorporating typical Cantor alloy elements (Fe, Co, Ni, and Cr) into a lightweight Al matrix. Both the HEF-strengthened alloy and pure Al were irradiated with 3 MeV Al ions at 150 °C, reaching a peak irradiation damage level of 50 dpa. The microstructural evolution of the HEF-strengthened Al was systematically investigated and discussed. Comparative analysis revealed that the HEF-strengthened Al exhibited significantly enhanced irradiation resistance compared to pure Al. This improvement is attributed to the Cr–Al atomic exchange mechanism proposed in this study, wherein Cr atoms migrate from the HEFs into the matrix, while Al atoms diffuse in the opposite direction. The two materials exhibit different degrees of irradiation-induced hardening rate, which can be explained by the evolution of HEFs and irradiation-induced defects. These findings offer valuable insights into the development of lightweight, irradiation-resistant structural materials for space nuclear reactors.