Global self-organization of solute induced by ion irradiation in polycrystalline alloys

Most materials are brought into nonequilibrium states during processing and during their service life. Materials for nuclear and space applications, for instance, are continuously exposed to energetic particle irradiation, which is often detrimental to materials’ performance. Here we demonstrate, however, that sustained irradiation can induce self-organization of the microstructure of polycrystalline alloys into steady-state patterns and, in turn, improve their radiation resistance. Using an Al −1.5 at.% Sb alloy as a model system, we show using transmission electron microscopy and atom probe tomography that, for nanocrystalline thin films irradiated at 75 °C with 2 MeV Ti ions to large doses, the microstructure consists of finite-size, self-organized AlSb nanoprecipitates inside the grains and along the grain boundaries. Furthermore, this steady state is independent of the initial microstructure, thus self-healing. Phase field modeling is employed to construct a steady-state phase diagram and extend the experimental results to other alloy systems and microstructures. Irradiation of alloys typically introduces changes to the atomic- and micro-scale structure, degrading performance. Here, sustained irradiation of an Al-Sb alloy causes self-organization that stabilizes the microstructure, improving radiation resistance.