β Scribed by M. Militzer; J. Wieting
No coin nor oath required. For personal study only.
The kinetics of impurity segregation to surfaces and grain boundaries are investigate within a phenomenological theory. The process is determined by volume diffusion. The nature of the boundary conditions is taken into account in the framework of regular solution. Coupled integral equations describing the time evolution of segregation in multicomponent systems are derived. Computer simulations were carried out for systems showing site competition and repulsive interaction between both segregants. It is found that characteristic nonequilibrium levels like segregation maxima occur. The influence of cooling rate is discussed with respect to stabilization of nonequilibrium segregation.
cinbtique de la segregation des impuretes d'un metal a la surface et aux joints de trains est recherchee a I'aide dune theorie phenomenotogique. Ce processus est determine par la diffusion de volume. Au cadre du modble de la solution regulibre est satisfait de la nature des conditions aux timites. Des equations integrales coupltes lesquelles &rivent l'evolution de temps de la segregation dans le systeme a composantes multiples sont derivees. On a fait des calcules a I'aide d'un computer pour des systtmes auxquelles existent la competition d'emplacement et des interactions repulsives entre deux sortes des atomes en segregation. On trouve des itats-desequilibres caracteristiques en forme des maxima de la segregation.
π SIMILAR VOLUMES
Dense polycrystalline mullite was equilibrated for 6 h in air at 1800 β’ C and then quenched to room temperature. During subsequent annealing at 1600 β’ C a gradual decrease of the Al 2 O 3 concentration in the grains occurs which approaches an equilibrium concentration after about 100 h annealing tim
Studies of the segregation behavior of particulate systems indicate the simultaneous occurrence of both segregation and mixing. The specific rate constants for these processes are calculated from statistical data and are shown to be a function of the particulate velocities. The results suggest the a