Irradiation tolerance enhanced by coherent interfaces of FCC/BCC HEA multilayers

Abstract

Eutectic high entropy alloys (EHEAs) with excellent mechanical properties are considered as potential nuclear structural materials due to their unique atomic-level microstructure and abundant heterogeneous interfaces. However, an understanding of EHEAs irradiation tolerance from the perspective of heterogeneous interface structure is still lacking. In this work, to explore the intrinsic mechanism of interface structure-irradiation tolerance in EHEAs, we constructed FCC/BCC high-entropy alloys (HEAs) multilayers with different interfacial structures by a radiofrequency (RF) magnetron sputtering. The prepared multilayers were irradiated at room temperature using 50 keV He+ in an ion irradiation and implantation facility. The irradiation-induced structural damage and irradiation-hardening behavior of the multilayers were systematically analyzed using X-ray diffractometer (XRD), transmission electron microscopy (TEM) and nanoindentation instrument, respectively. It is found that the coherent and semicoherent interfaces mainly affect helium (He) behavior in the multilayers. We demonstrate that the coherent interfaces enable HEAs to have lower bubble swelling and irradiation hardening capability by promoting the migration ability of He bubbles. These results provide insight into the role of interfacial structures in the irradiation tolerance of nanostructured EHEAs, which should lead us to reconsider some design rules for advanced radiation-tolerant materials.