Search

Abstract: Interface effects on ion-irradiation tolerance properties are investigated in nanolayered TiN/AlN films with individual layer thickness varied from 5nm to 50nm, prepared by pulsed laser deposition. Evolution of the microstructure and hardness of the multilayer films are examined on the specimens before and after He ion-implantation to a fluence of 4×1020 m−2 at 50keV. The suppression of amorphization in AlN layers and the reduction of radiation-induced softening are observed in all nanolayer films. A clear size-dependent radiation tolerance characteristic is observed in the nanolayer films, i.e., the samples with the optimum layer thickness from 10nm to 20nm show the best ion irradiation tolerance properties, and a critical layer thickness of more than 5nm is necessary to prevent severe intermixing. This study suggests that both the interface characteristics and the critical length scale (layer thickness) contribute to the reduction of the radiation-induced damages in nitride-based ceramic materials. [Copyright &y& Elsevier]

Abstract: We compare the evolution of microstructure and mechanical properties of Ag/Ni multilayers of varying layer thickness (1–200nm) subjected to helium ion and proton irradiation at room temperature to similar dose, ∼2 displacements-per-atom on average. Layer structure remained intact after both types of irradiation although defects accumulated in the layers are different. Helium bubbles were the major defects in helium ion irradiated films, while dislocation loops were ubiquitous in proton irradiated multilayers. In He ion irradiated multilayers, radiation hardening was greater than that in proton irradiated specimens, and the magnitude of hardening decreased with decreasing individual layer thickness. In comparison no size dependent hardening was observed in proton irradiated films. Mechanisms of irradiation induced hardening were discussed. [Copyright &y& Elsevier]