Concentration Dependence of Diffusion Coefficients In Metallic Solid Solution

Summary

1—Diffusion coefficients in the Cu-Pd system have been determined as a function of temperature and concentration. The concentration dependence is slight in both extremes of concentration and strong at intermediate concentrations. The diffusion coefficient approaches the value of the self-diffusion coefficient of copper in dilute palladium solution.

2—A redetermination of the dependence of the diffusion coefficients at the high copper end of the Cu-Ni system confirmed a strong dependence of the diffusion coefficient on composition in the relatively dilute solutions.

3—Individual diffusion coefficients for copper and nickel atoms have been found by the use of markers at 89.9 atomic pct Cu. D_Cu is about 30 pet greater than D_Ni over the temperature range 923° to 1049°C.

4—The deviation of the diffusion coefficient at infinite dilution from the self-diffusion coefficient of the solvent metal is generally greater the greater the melting-point depression. Both factors also tend to become greater the more limited the solid solubility of the solute metal.