Question

Stress fields around dislocations cause:

• A. Ductility increase
• B. Lattice distortion
• C. Phase transformation
• D. Grain refinement

Hint:

Stress fields around dislocations distort the regular atomic arrangement, causing lattice distortion — a key concept in understanding mechanical properties of materials.

Answer 1

The Correct Option is B

Dislocations are line defects in crystalline solids, and they are associated with stress fields that disturb the regular atomic arrangement around them. These stress fields extend into the surrounding lattice and result in lattice distortion.
- The atoms near a dislocation line are displaced from their equilibrium positions due to these stress fields.
- This distortion plays a key role in influencing mechanical behavior, such as yield strength and strain hardening.
- While dislocations are necessary for plastic deformation, their accumulation can also hinder further dislocation motion, contributing to strengthening mechanisms like work hardening.
The other options are not directly caused by dislocation stress fields:
- Ductility increase may occur in general plastic deformation but not directly due to dislocation stress.
- Phase transformation and grain refinement involve thermodynamic and microstructural processes, not just local stress effects.