Liquid Film Migration in a Cu-5 At.% Sb Alloy

Abstract

Liquid film migration was studied in a Cu-5 at % Sb alloy by both down-quenching and up-quenching from the initial liquation temperature in the two-phase, α + liquid, field. The time and temperature dependence of the migration distance and the rate of migration were studied in the temperature range of 440 to 760 °C. A near parabolic growth behaviour was observed. The coherency strain energy as calculated from the composition of the trailing grain was observed to be one order of magnitude higher than the interfacial energy of the cylindrical liquid film. The total chemical free energy was calculated to be one to three orders of magnitude higher than the coherency strain energy. A substantial part of the total chemical free energy is used for volume diffusion in front of the liquid film in the receding grain. The diffusion coefficients and the activation energy calculated at 730 to 760 °C correspond to those of the diffusion of Sb in liquid Cu. The activation energy is close to those of self diffusion in liquid Sb and Cu.

Liquid film migration was studied in a Cu-5 at % Sb alloy by both down-quenching and up-quenching from the initial liquation temperature in the two-phase, α + liquid, field. The time and temperature dependence of the migration distance and the rate of migration were studied in the temperature range of 440 to 760 °C. A near parabolic growth behaviour was observed. The coherency strain energy as calculated from the composition of the trailing grain was observed to be one order of magnitude higher than the interfacial energy of the cylindrical liquid film. The total chemical free energy was calculated to be one to three orders of magnitude higher than the coherency strain energy. A substantial part of the total chemical free energy is used for volume diffusion in front of the liquid film in the receding grain. The diffusion coefficients and the activation energy calculated at 730 to 760 °C correspond to those of the diffusion of Sb in liquid Cu. The activation energy is close to those of self diffusion in liquid Sb and Cu.

On a étudié la migration de film liquide dans un alliage de Cu-5% at. Sb tant par trempe basse que par trempe élevée à partir de la température initiale de liquation dans le domaine à deux phases, α + liquide. On a étudié la dépendance de la distance de migration et du taux de migration sur la durée et la température, dans une gamme de température de 440 à 760 °C. On a observé un comportement de croissance presque parabolique. On a observé que l'énergie de déformation cohésive, telle que calculée à partir de la composition du grain de talonnement, était d'un ordre de grandeur plus élevée que l'énergie interfaciale du film liquide cylindrique. On a calculé que l'énergie chimique libre totale était de un à trois ordres de grandeur plus élevée que l'énergie de déformation cohésive. Une partie substantielle de l'énergie chimique libre totale est utilisée pour la diffusion volumique en avant du film liquide dans le grain qui s'efface. Les coefficients de diffusion et l'énergie d'activation, calculés de 730 à 760 °C, correspondent à ceux de la diffusion du Sb dans le Cu liquide. L'énergie d'activation est proche de celles de l'auto-diffusion dans le Sb et le Cu liquides.