An atomistic study of tilt grain boundaries with substitutional impurities

摘要: Abstract An atomistic study of symmetrical [001]tilt boundaries in f.c.c. metals with a non-equilibrium distribution substitutional impurities the has been carried out. The atomic interactions described previous paper have used. They consist empirically constructed pair potentials and density dependent terms. contribution to total energy is relaxed together central force contribution, which produces an overall volume change block. Bismuth silver as solute atoms copper, gold studied. relaxations associated array periodically widely spaced otherwise ideal crystals two hosts are examined first. grain studied ∑ = 5 (210), 36.87° bE 17 (530), 28.07°. In both structure (530) boundary consists units (210) one octahedron from crystal orientation. Impurity were then introduced successively at sites five boundaries. impurity large repeat cell so that only low concentrations considered. For each case segregation. Eγ selected, concomitant relaxation host energy. Δγb found. Es found be very sensitive local environment atom there not substantial difference segregation propensity selected. cause larger distortion expansion copper than does silver. for former governed principally by size effect while this can partially explain variation various copper. Segregation energetically favorable all considered gold. It shown must implicit dependences on physical chemical parameters solvent, corresponding alloy, value dominated any specific strong environment. This leads selectivity sites. Possible implications results understanding segregation, effects facetina embrittlement discussed.