A molecular-dynamics simulation of grain-boundary diffusion of niobium and experimental investigation of its recrystallization in a niobium-copper system

Amorphous-Nanocrystalline Composites Prepared by High-Pressure Torsion

“…The appearance of an amorphous phase in the near-interface areas was first experimentally established in our investigation by the methods of direct-resolution TEM (Figure 13a,b) and XRD ( Figure 16). This confirms the hypothesis [48][49][50] on the possibility of the clustered structure of the regions containing simultaneously copper and niobium atoms. In a rather detailed scientific work [47], no amorphous phases have been detected in the Cu-Nb nanolaminates after SPD, but nonequilibrium supersaturated solid solutions of Cu-Nb (up to 1.5 at.…”

“…The energy anisotropy of the interface in a system of non-miscible elements was first studied in [48][49][50] by the example of molecular-dynamics simulation of Cu/Nb bicrystals. It was established that the mechanism of niobium dissolution in the copper matrix involves the formation of niobium clusters coherent with the matrix.…”

“…The observed [48][49][50] phenomenon of niobium cluster dissolution near the Cu/Nb interface of finite curvature is proposed as a physical explanation of the amorphization of such interface. Because of the lattice distortion by clusters, a sharp TEM image of the projection of close packed copper atom rows in the interface region disappears, and such regions are recognized as amorphous.…”

“…In the process of migration of the Cu/Nb interphase boundary is possible to incorporate of nanolamellas of one metal into another with the subsequent formation of isolated monatomic clusters. The crystal structure was distorted in cluster and lamella regions, which could be perceived as amorphization of the interphase boundary in studies by the methods of high-resolution microscopy [48].…”

Precipitates in coarse-grained heat-affected zone of Ni-based 718 superalloy produced by tungsten inert gas welding

“…The alloy elements diffuse quicker in the boundary area and precipitate easily from austenite than inside the grains, as studied by Lipnitskii et al (2013). The dissolution of precipitates, especially M 23 C 6 particles, is the primary diffusion process.…”