Strengthening Mechanisms

Strengthening mechanism discuss the ways by which the flow strength of crystalline material is increased by restricting motion of the dislocations.

It is quite clear that permanent deformation in materials occures due to motion of dislocation within it. And to create a metal having high strength we might have to eliminate all the dislocation i.e., making it whiskers. But eliminating all the dislocation from a crystalline solid is practically not favorable. However, the strength of a crystalline material can be increased by some obstacles that restrict the motion of dislocation present within it.

Barriers to the motion of dislocation :
A dislocation can not move due to presence of the obscles such as -

1. Dislocation nodes
2. Precipitates
3. Grain boundary
4. 2nd phase particles

These obscles can act alone or as a conbinations to restrict the the motion of dislocation.

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Methods of strengthening metal against yield :