Dislocations and Strengthening Mechanisms

This set of flashcards covers vocabulary related to dislocations and strengthening mechanisms in engineering materials, focusing on definitions and key concepts.

Dislocation

A linear defect in a crystal structure that affects plastic deformation.

Slip

The movement of dislocations through a crystal when stress is applied.

Peierls-Nabarro stress

The stress needed to drive a dislocation through a crystal continuously.

Dislocation density

The total length of dislocations per unit volume in a material.

Grain boundaries

Interfaces between different grains in a polycrystalline material that act as barriers to dislocation motion.

Cold working

A process that increases dislocation density to strengthen metals through plastic deformation.

Grain size reduction

A strengthening mechanism wherein smaller grains increase yield strength due to more grain boundaries.

Critical resolved shear stress (CRSS)

The minimum shear stress required to initiate slip in a crystal.

Solid solution strengthening

A strengthening mechanism where impurity atoms distort the lattice and impede dislocation motion.

Strain hardening

An increase in strength and hardness of a metal due to plastic deformation.

Slip system

The combination of a slip plane and a slip direction in a crystal.

FCC (Face-Centered Cubic) structure

A crystal structure with specific slip planes and directions, noted for having 12 slip systems.

Heat treatment

A process involving heating and cooling that alters the microstructure and properties of materials.

Recovery

The first stage of heat treatment where dislocations are reduced without changing the microstructure significantly.

Recrystallization temperature (TR)

The temperature at which recrystallization reaches completion within one hour.