Kinetics in materials engineering involves how a system approaches equilibrium, i.e. microstructural evolution: diffusion equation, diffusion in the atomic level, diffusion in crystals and and noncrystalline materials, surface and interface structure and formation, motion of dislocations, phase transformations—diffusional, such as nucleation and growth for solidification, and diffusionless, such as martensitic— and crystallization, reaction/mixture kinetics.