Faceting–roughening transition of a Cu grain boundary under electron-beam irradiation at 300 keV

Abstract

In this study, we examined the beam-irradiation effect on the structural evolution of the grain boundary (GB) in a Cu bicrystal at room temperature using a Cs-corrected, monochromated transmission electron microscope at an acceleration voltage of 300 keV. Faceting of the GB was observed at a low current density of the electron beam. With increasing current density, the GB became defaceted. The faceting–roughening transition was shown to be reversible, as the process was reversed upon decreasing the current density. The structural transition is explained by inelastic scattering effects by electron-beam irradiation.

Atomic-scale observation of dynamic grain boundary structural transformation during shear-mediated migration

“…S13, C and D). Given that Σ11(113) STGB and (002)/(111) ATGB are found to be preserved as much as possible in the GBs vicinal to these special geometrics, such as 52.9° [110] tilt GB (31), and GB faceting is also prevalent in various types of GBs (table S3) (24,31,32,40,(45)(46)(47)(48)(49)(50)(51)(52)(53)(54)(55), it is thus reasonable to believe that the faceting/ defaceting process and resultant facet transformation mechanisms discussed here could have a general implication to the understanding of the structural evolution of faceted GBs during stress-driven migration in nanocrystalline or polycrystalline materials (additional examples of stress-driven facet transformation can be found in figs. S15 and S16).…”