What are the types of diffusion and describe the two atomic

What are the types of diffusion and describe the two atomic mechanisms of diffusion?

Solution

different types of deffusions are:

1.contagious

2.hierarchical

3.stimulus

4. relocation

the two atomic mechnisms of deffusion are:

1.vacncy diffusion mechanism:

-To jump from lattice site to lattice site, atoms need energy to break bonds with neighbors, and to cause the necessary lattice distortions during jump.

-This energy comes from the thermal energy of atomic vibrations (Eav ~ kBT) The direction of flow of atoms is opposite the vacancy flow direction.

2.interstitial diffusion mechanism:

-Interstitial diffusion is generally faster than vacancy diffusion because bonding of interstitials to the surrounding atoms is normally weaker and there are many more interstitial sites than vacancy sites to jump to.

-Requires small impurity atoms (e.g. C, H, O) to fit into interstices in host.