Liquid diffusion in aluminum.

摘要

The liquid diffusivity of copper solute in aluminum was measured at ranges of 700-800°C. A long capillary method was developed for the creation and testing of liquid diffusion couples, in order to quantify the extent of convective flow in previous studies which utilized a capillary reservoir technique. Convective flow was found to have an effect of increasing liquid diffusion by a factor of 2-3.; The liquid diffusivity of iron solute in aluminum was also measured and compared to those of copper, in order to study the effect of solute valency on diffusion. It was found that while the effect on diffusional activation energies matched theory (the larger the negative relative valence, the greater the activation energy), this had little bearing on overall liquid diffusion rates in terms of temperature dependance in an Arrhenius relation. Furthermore, the overall magnitude of the diffusion rates was contrary to theory (where higher activation energies should result in slower diffusion rates), suggesting that while liquid diffusion does exhibit an Arrhenius temperature dependence, solute valency is not a major determining factor in liquid diffusion rates.