Influence of ion irradiation on the nanomechanical properties of thin alumina coatings deposited on 316L SS by PLD

In terms of nuclear applications, ceramics are seen as a particularly promising class of materials due to their chemical inertness and relatively high radiation resistance. However, since ceramics exhibit high brittleness at low homologous temperatures, the application of monolithic ceramics as structural components of nuclear power plants is rather limited. On the other hand, deposition of ceramic coatings on a metallic substrate may result in an excellent combination of mechanical, corrosion and radiation properties (especially at high temperature). In this work, Al2O3 coatings deposited by Pulsed Laser Deposition (PLD) on 316L SS substrate at room temperature were investigated. In order to simulate the influence of neutrons, alumina-coated and 316L SS samples were irradiated at room temperature with 250 keV Au+ and 150 keV Fe2+ ions, respectively. The influence of ion irradiation on nanomechanical properties of the studied materials was investigated by means of Nanoindentation (NI) technique. Based on the obtained results, nanomechanical properties as a function of radiation damage level were determined and linked to the results of Grazing Incidence X-Ray Diffraction (GIXRD) analysis and other structural data available in the literature. Irradiation-induced softening and hardening were observed, respectively, in the alumina coating and 316L SS. Reported differences, which are induced by the irradiation effects, are considered to be due to the different microstructures of the pristine materials. •The hardness of the alumina coating drops and reaches maximum level upon which it increases and saturates for the high dpa•The hardness of 316L SS increases rapidly up to 3 dpa, and tends to saturate once this limit is achieved•Reported differences induced by the irradiation effects are considered to be due to the different microstructural features