MTL 200 Lecture 5: Chapter 5

• School: Ryerson University
• Department: Mechanical Engineering
• Course: MTL 200
• Professor: Ahmad Varvani- Farahani

Document Summary

Diffusion: a phenomenon of material or mass transport by atomic motion. Inter diffusion (impurity diffusion): diffusion (migration) of atoms of metal into another metal. Two conditions for an atom to migrate: an empty adjacent site, sufficient vibrational energy to break bonds. 5. 2. 2 interstitial diffusion (h, c, n, o in metals) Mc question: this type of diffusion, occurs more rapidly than vacancy diffusion because of: smaller and mobile interstitial atoms, more empty interstitial sites than vacancies. Diffusion flex (j): the rate of mass transfer, the unit is = Where m is the diffusion mass, a is the diffusion area and t is the diffusion time. Steady stare diffusion: the diffusion condition in which the diffusion flux is independent of time. Concentration profile: the curve of the concentration versus the position in a material. Concentrating gradient: the slope of the concentration profile at a specific point. U is the driving force in the steady stare.