Impacts of E-Beam Irradiation on Polycrystalline Metals in Both Bulk and Thin Film Forms

Abstract

This study aims to explore the impact of e-beam irradiation on the mechanical and structural characteristics of four different polycrystalline metals (Ni, Cr, V, and Ti), in both bulk and thin film forms. Thin metal films are fabricated using magnetron sputtering. The primary goal is to identify suitable metal candidates for growing thin films, which could serve as exit windows for e-beam accelerators. This selection is based on their properties, power dissipation capabilities, and the effects of irradiation on mechanical attributes such as hardness, ductility, defect density, and strength.For the bulk polycrystalline metal samples, a series of nanoindentation tests has been conducted before and after e-beam irradiation to investigate changes in hardness and elastic modulus. Additionally, to compare performance with the bulk samples, thin metal films are subjected to the same procedure before and after irradiation, allowing for the evaluation of film hardness, moduli, and creep properties. Results indicate that irradiated bulk samples of Ni, Cr, and V become harder, whereas Ti experiences softening. There is no significant irradiation effect on modulus for all for polycrystalline metal samples. To understand the underlying reasons behind these effects, both the fabricated metal films and bulk metal samples undergo comprehensive characterization tests for their microstructural properties, elastic behavior, and chemical composition. This involves the utilization of SEM with EDS, FESEM and AFM to analyze microstructure and surface attributes of the films, followed by X-ray diffraction to gain insight into film morphology and lattice orientation.