Grain boundary diffusion coefficient
Encyclopedia
The grain boundary diffusion coefficient is the diffusion coefficient (during atomic diffusion
) of a diffusant along a grain boundary
in a polycrystalline
solid. At lower temperatures in metals and metal alloys, this diffusion term may dominate the effective diffusion rate
.
Atomic diffusion
Atomic diffusion is a diffusion process whereby the random thermally-activated movement of atoms in a solid results in the net transport of atoms. For example, helium atoms inside a balloon can diffuse through the wall of the balloon and escape, resulting in the balloon slowly deflating. Other air...
) of a diffusant along a grain boundary
Grain boundary
A grain boundary is the interface between two grains, or crystallites, in a polycrystalline material. Grain boundaries are defects in the crystal structure, and tend to decrease the electrical and thermal conductivity of the material...
in a polycrystalline
Polycrystalline
Polycrystalline materials are solids that are composed of many crystallites of varying size and orientation. The variation in direction can be random or directed, possibly due to growth and processing conditions. Fiber texture is an example of the latter.Almost all common metals, and many ceramics...
solid. At lower temperatures in metals and metal alloys, this diffusion term may dominate the effective diffusion rate
Effective diffusion coefficient
The effective diffusion coefficient of a diffusant in atomic diffusion of solid polycrystalline materials like metal alloys is often represented as a weighted average of the grain boundary diffusion coefficient and the lattice diffusion coefficient...
.
See also
- Kirkendall effectKirkendall effectThe Kirkendall effect is the motion of the boundary layer between two metals that occurs as a consequence of the difference in diffusion rates of the metal atoms...
- Phase transformations in solids
- Mass diffusivity