Diffusion in heterogeneous solid bodies

Summary The results are presented of an evaluation of diffusion in heterogeneous solid bodies for various initial conditions.     

Diffusion in ternary Ag-Zn-Cd solid solutions

Diffusion in the Ag-Zn-Cd system was investigated at 600°C with semi-infinite, vapor-solid couples in order to evaluate intrinsic diffusion coefficients and interdiffusion coefficients in theα andβ phases. Intrinsic diffusion coefficients were determined at several composition points in theα-phase region along concentration lines of 11 at. pct Zn, 18 at. pct Zn, 5 at. pct Cd, and 9 at. pct Cd. Interdiffusion coefficients in theα phase were determined at several points of intersection of various composition paths; these composition points of intersection were along lines of constant zinc-to-cadmium concentration ratios of 3.8, 1.8, and 1.2. All two-phase diffusion couples developed planar β/α interfaces. Intrinsic coefficients were computed at three composition points in the β region corresponding to a silver concentration of approximately 55 at. pct. Intrinsic coefficients for β alloys are two to three orders of magnitude larger than those for α alloys. P. T. CARLSON, formerly Donnan Fellow, School of Materials Science and Metallurgical Engineering, Purdue University, Lafayette, Ind., This paper is based on a thesis submitted by P. T. CARLSON in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Purdue University.     

The diffusivity of lattice atoms in dilute interstitial solid solutions

The enhancement of the diffusivity D of host atoms in a lattice containing dissolved interstitial atoms has been discussed in terms of a model in which the enhancement is due to complexes formed due to vacancy-(interstitial atom) interactions and a model which considers that the enhancement is primarily due to the lattice dilation caused by the presence of the interstitial atoms. The validity of these two concepts is discussed in terms of experimental data.