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.