Materials, Properties and Design

· Creep processes involve material movement at the atomic scale.
· Diffusion processes transport atoms through the bulk of the material, along boundaries between crystals in poly-crystalline materials, and over surfaces.
· The diagram shows the correlation between the activation energy for the self diffusion of atoms through the bulk of various materials and the activation energy associated with high temperature creep.

· The linear relationship between these two activation energies for the materials shown indicates that bulk diffusion controls creep deformation in this temperature region.

From: Courtney, "Mechanical Properties" McGraw Hill (1990)