Low-dose damage evolution in pure magnesium under electron irradiation: Effect of foil orientation and pre-existing dislocations Article Swipe
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· 2024
· Open Access
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· DOI: https://doi.org/10.1016/j.nme.2024.101845
· OA: W4405337337
Low-dose damage evolution in commercial purity (99.95 wt%) magnesium has been investigated, under 200 keV electron irradiation at room temperature, up to ∼0.03 displacements per atom. Quantitative defect production and evolution statistics were obtained for two types of prism foils (z = [12¯10], [101¯0]), in samples of as-received and heat-treated (400 °C/1 h) condition. An incubation period was found to produce visible damage in all samples, in correspondence with about ⅓ of the maximum dose. The damage microstructure consisted of basal-plane 16<202¯3> loops, exclusively; while no voids were observed throughout the course of irradiations. Steady-state accumulation of dislocation loops was found at doses beyond the incubation limit in heat-treated samples. Higher loop number density and large loop average size were confirmed in [12¯10] than in [101¯0]. One-dimensional loop rafts were developed via elastic interaction. In as-received samples, the presence of pre-existing dislocations (on the order of 1014 m−2) gave rise to suppressed build-up of loop population. Saturation of loop growth was confirmed, when loop average size reached ∼20 nm. Underlying mechanisms of foil orientation effect and pre-existing dislocation effect upon microstructure development are discussed. The paper concludes with a brief comparison between electron irradiation and fission neutron irradiation in magnesium, aiming to bring new insights upon displacement damage studies in materials with hexagonal close-packed structure.
