Ternary diffusion in Cu-Ni-Zn alloys at 1133 K

Abstract

The interdiffusion coefficients in the α fcc phase of Cu-Ni-Zn alloys D_ZnZn ^Cu, D_ZnNi ^Cu, D_NiNi ^Cu and D_NiZi ^Cu at 1133 K have been determined by an extended Boltzmann-Matano method. The major coefficients D_ZnZn ^Cu and D_NiNi ^Cu are positive, and the crosscoefficients D_ZnNi ^Cuand D_NiZn ^Cu are negative. A pronounced concentration dependence of the four interdiffusion coefficients is observed, D_ZnZn ^Cu being particularly sensitive to composition. From the estimated, values of interaction parameters, it is considered that the interaction energy of the Ni-Zn bond at 1131 K is much larger than the values for the Cu-Zn and Cu-Ni bonds. The tracer diffusion coefficients D_Zu*, D_Ni* and D_Cu* calculated from the equations of Zieboldand Ogilvie are in the order D_Zu* > D_Cu* > D_Ni*. In addition, the calculated intrinsic diffusion coefficients D_ZnZn ^Cu and D_NiNi ^Cu are positive, and the four other coefficients are negative.