MS&E #7 Dislocations and Strengthening

13 flashcards · Physics · by Kristóf Nagy

1. Slip

   Irrecoverable, permanent deformation of a crystal lattice due to the motion of dislocations under an applied shear stress.

2. Slip system

   Combination of a crystallographic plane and a direction within that plane on which slip can occur in a crystal.

3. Solid-solution strengthening

   Strengthening of a metal through the introduction of foreign atoms into the crystal lattice, which disrupt the regular array of atoms and create lattice strains.

4. Strain hardening

   The process of increasing the strength and hardness of a metal through cold working, which creates additional dislocations and entangles them, making it more difficult for subsequent dislocations to move. Also known as work hardening.

5. Cold working

   The process of mechanically deforming a metal at room temperature or slightly above, leading to an increase in strength and hardness due to an increased dislocation density and strain hardening.

6. Critical resolved shear stress (CRSS)

   The minimum shear stress required to initiate dislocation motion (slip) on a specific slip system in a single crystal.

7. Dislocation density

   Total length of dislocations per unit volume of material. It is usually expressed in units of inverse length squared (e.g., mm^-2).

8. Grain growth

   The increase in average grain size of a polycrystalline material over time due to grain boundary migration and coalescing.

9. Lattice strain

   Localized distortion of a crystal lattice caused by the presence of impurity atoms, dislocations, or other defects.

10. Recovery

    The process of relieving residual stresses and restoring some of the original properties of a cold-worked metal through annealing at moderate temperatures.

11. Recrystallization

    The formation of new, strain-free grains in a cold-worked metal through annealing at higher temperatures. This results in a significant decrease in strength and hardness but an improvement in ductility.

12. Recrystallization temperature

    The minimum temperature at which recrystallization can occur in a cold-worked metal within a reasonable period of time.

13. Resolved shear stress (RSS)

    The component of the applied shear stress acting on a specific slip system in a single crystal. It is calculated as the product of the applied stress and the cosine of the angle between the stress direction and the normal to the slip plane.