CH 5 - Diffusion Flashcards
1
Q
What is diffusion?
A
mass transport by atomic motion
2
Q
What is interdiffusion?
A
in an alloy, atoms tend to migrate from regions of high concentrations to regions of low concentrations
3
Q
What is self-diffusion?
A
atom migration in an elemental solid
4
Q
What is vacancy diffusion?
A
- atoms exchange with vacancies
- applies to substitutional impurities atoms
- rate depends on # of vacancies & activation energy to exchange
5
Q
What is interstitial diffusion?
A
- smaller atoms can diffuse between atoms
- more rapid than vacancy diffusion
6
Q
Is diffusion faster for open or close-packed crystal structures?
A
open crystal structures
7
Q
Is diffusion faster for materials with covalent bonding or secondary bonding?
A
secondary bonding
8
Q
Is diffusion faster for bigger or smaller diffusing atoms?
A
smaller
9
Q
Is diffusion faster for higher or lower density materials?
A
lower
