Enhancing irradiation tolerance of Mg-Mn based alloys via tailoring Mn nanoprecipitates

Magnesium alloys act as potential candidate nuclear materials due to their excellent chemical compatibility and neutron economy. In this work, the irradiation behavior of pure Mg, Mg-3Mn and Mg-3Mn-0.5Ca alloys were studied via Xe⁺ implantation at room temperature. Transmission electron microscopy (TEM) results show the formation of dislocation loops, Xe bubbles and Mn nanoprecipitates in irradiated Mg samples. For Mg-3Mn alloy, the high density of Mn nanoprecipitates are formed periodically along the basal plane after Xe irradiation. It is noted that these nanoprecipitates could suppress the nucleation and growth of Xe bubbles to reduce the swelling ratio (only, 0.011 %), which is much less than that of pure Mg. In contrast, the pre-existing Mn particles in the Mg-3Mn-0.5Ca alloy will cause the absence of Mn nanoprecipitates under Xe irradiation. In addition, the irradiation-induced Mn nanoprecipitates could restrict the growth of c-loops and facilitate more c-loops nucleation. Eventually, under the irradiation dose of 9.7 dpa, a high-density c-loop dislocation is formed, with no detectable a-loop formation in the Mg-3Mn sample. The present study could provide a reference for designing the irradiation resistance Mg alloys.