A modeling approach to predict the mechanical response of materials to irradiation damage from external sources: nanoindentation of Pb-implanted ZrSiO4

Materials exposed to external irradiation undergo damage and detoriation of mechanical properties that decays with the distance from the surface. Finite element simulations are used to predict the hardness and Young´s mod- ulus as function of depth. The model incorporates the homogenized mechanical properties and the volumetric swelling, determined from micromechanical simulations, as function of the locally induced damage. Predicted Young’s modulus data showed a good agreement with nanoindentation results and confirmed the established mapping of damage into depth dependent amorphous phase fraction in form of sigmoidal functions. The com- parison of predicted hardness profiles with experimental data suggests a relaxation mechanism that removes the residual stress in the damaged surface layer during the ion implantation process. Furthermore, the results support the hypothesis that mechanical properties determined from intrinsic damage can be used to model also external radiation damage. The presented model is applicable to other types of materials and irradiation sources.