Helium irradiation-induced swelling resistance of heterogeneous nanoparticles in an iron-based multi-principal element alloy

Abstract

In this work, we studied the resistance to helium-irradiation-induced swelling of the Fe6Cr1.2Mn0.8Cu1.5Mo0.3V0.2 alloy containing highly thermally stable Cu nanoprecipitates for nuclear applications using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). The results show that the Cu nanoprecipitate/matrix interface and the nanoprecipitate itself can trap helium bubbles, creating open volume sinks of helium bubbles; large helium bubbles tend to be dispersed at the interface, while small helium bubbles are distributed in the matrix. The SAXS results indicate that the average size of helium bubbles is 1.3–1.7 nm, and the distribution of helium bubbles in the two samples varies due to the difference in Cu nanoprecipitation/matrix interface density, which was also verified via TEM. In addition, a low swelling ratio (0.05%/dpa) of the alloy was calculated, further confirming the feasibility of heterogeneous nanoprecipitation management of helium damage in irradiation tolerant materials. These nanostructured materials have the potential to reduce the helium effect by providing more nucleation sites for helium bubbles.