Microstructural characteristics of pure nickel foils under argon ion irradiation

Abstract

BackgroundNickel -based superalloys are widely used in high temperature structural materials and have important applications in nuclear materials. Radiation damage characteristics are the key factors to evaluate the properties of nuclear materials.PurposeThis study aims to investigate the effect of ion irradiation on the microstructure of metal materials.MethodsThe annealed pure nickel block was preliminarily cut into thin foils and pre-thinning. Then, the pit thinning, twin-jet electropolishing and other processes were applied to further thin the foil samples until they became electron-lucent. The pure nickel foils were irradiated by 120 keV argon ions (Ar+) with three different doses. The irradiation defects and deformed structures in the pure nickel foils were characterized by transmission electron microscope.ResultsThe pure nickel foils have significant radiation damage after the Ar+ irradiation. At the low Ar+ irradiation dose, the irradiation defect clusters are dominated by black spot defects, which contained a large number of stacking fault tetrahedrons. The void defects occur at the relatively high Ar+ irradiation dose. With the increase of Ar+ radiation dose, the number density of void defects increases, while the size of void defects increases first and then decreases.ConclusionsUnlike bulk pure nickel, the argon ion irradiation with relatively high dose is able to induce expansion dislocation and deformation twin in the pure nickel foils. This is because the decrease of material size can weaken its symmetry and inhibit the initiation of the dislocation slip system.

Keywords

• argon ion
• pure nickel foil
• microstructure
• defect clusters
• deformation twins