Question

The multiplication of dislocations is explained by:

• A. Twinning mechanism
• B. Griffith theory
• C. Frank–Read source
• D. Edge slip

Hint:

Frank–Read source is the primary mechanism by which dislocations multiply during plastic deformation, enabling continuous flow in metals.

Answer 1

The Correct Option is C

The Frank–Read source is a mechanism that explains how dislocations multiply within a crystal under applied stress. It is a fundamental concept in dislocation theory and plays a key role in understanding strain hardening and plastic deformation.
When a dislocation line is pinned at two points and stress is applied, the central segment bows out due to shear. Eventually, it forms a dislocation loop and breaks away, leaving behind the original dislocation line, which can then repeat the process. This generates multiple dislocations from a single one.
Other options:
- Twinning is a deformation mechanism but does not involve dislocation multiplication.
- Griffith theory explains fracture in brittle materials.
- Edge slip is a dislocation motion mode, not a multiplication mechanism.