The SMME process relies on atomic diffusion mechanisms in the respective diffusor-mediator system. An overview of the various mechanisms is provided to illustrate the required compatibility of diffusor-mediator. While various other conditions are important to the successful incorporation of the diffusor (e.g. low diffusor solubility in mediator and rarity of diffusor-mediator compounds and alloys), the most significant requirement is the average diffusion length of the diffusor in the mediator.

Permanent incorporation of diffusors at the buried interface such that they no longer contribute to the net atomic diffusor concentration in the mediator is a necessary condition. The effective incorporation of diffusors at the buried interface is primarily governed by the existence of lattice site free energies typically lower than those encountered at bulk mediator lattice sites.