To perform a similar type of analysis, consider the following hints and recommendations:
The elements CONTA174 (3D surface-to-surface contact) and TARGE170 (3D surface-to-surface target) support the TEMP, VOLT, and CONC degrees of freedom. Use these contact elements to connect dissimilar meshes, to model contact resistance, or to model imperfect contact.
Use large time steps in a transient analysis. For example, in this problem time steps of 1x106 seconds and larger are used. Small steps are unnecessary and may contribute to spatially varying concentration oscillations. A steady-state (static) analysis is also possible.
Use the postprocessing commands PLVECT,CG (concentration gradient) and PLVECT,DF (diffusion flux) to observe atomic divergence.
Due to very low atomic diffusivity, materials such as copper may show spatially varying concentration oscillations. In such cases, a tetrahedral mesh of these regions may be preferred.