Occurrence of Faceting for [110] Symmetric Tilt Boundaries in Cu Doped with Bi

Abstract

The faceting of the grain boundary in the binary Cu-Bi system was experimentally observed by transmission electron microscopy (TEM). For the observation, Cu bicrystals with AE33, AE9 and AE11 [110] symmetric tilt boundaries were doped with Bi at 1173 K for 120 h, and then homogenized at 1173 K for 48 h, followed by furnace cooling or water quenching. The misorientation angle between the [001] directions of the two single-crystals is 20.1 , 38.9 and 50.5 for the AE33, AE9 and AE11 boundaries, respectively. According to the TEM observation, the grain boundary is faceted markedly in the bicrystal with furnace cooling but barely in that with water quenching. Thus, the faceting takes place during furnace cooling but not during homogenization. The faceting was analyzed quantitatively on the basis of the inclination angle dependence of the boundary energy in Cu. The analysis yields that the contribution of the torque term to the faceting is important. Comparing the boundary diffusivities of Bi and Cu in Cu, we may expect that the mobility is much greater for the grain boundary with Bi than for that without Bi. As a result, the faceting during furnace cooling takes place considerably for the grain boundary with Bi but scarcely for that without Bi.

Review: grain boundary faceting–roughening phenomena

“…However, the number of faceted GBs in Cu-30 9 10 -3 at.% Bi alloys was very high [140] because this concentration is well above the GB solidus. The formation of facets after doping of Cu R11 bicrystal with bismuth has been directly observed in [142].…”

Origin of differences in the excess volume of copper and nickel grain boundaries

“…Segregation of elements to GBs and their modified diffusion is also an issue that has received considerable attention [24e26]. For example, segregation of H and Bi to GBs in palladium and copper has been probed using techniques such as TEM and activity measurements [27,28]. The modified diffusion of impurities along GBs in metals have also been studied using the tracer diffusion method [10,29].…”

Interfaces of Mixed Crystallographic Planes of NiO Nanograins

“…For example, joining of the (1̅11) and (11̅1) surfaces, which have an angle of 109.5°, forms the Σ3 (111) boundary. These interfaces have been studied experimentally and subjected to high-resolution TEM analysis. – The usual asymmetric [110] tilt boundary, formed by replacing the symmetric interface with a vicinal surface inclined at a small angle to it, has also been well studied experimentally and theoretically. – …”