Metals Science

Metals represent a vital class of materials for a technological society. This course examines the structure and properties of metals across a range of length scales, addressing issues of microstructural changes and phase transformations, metals production techniques and the behaviour of metals in generic applications.

The course covers microstructures, mechanical properties in relation to microstructures and crystallographic aspects of physical metallurgy.

Microstructural aspects include:

1. Basic elements of the plasticity of metal alloys including concepts such as the theoretical strength of single crystals, plasticity by dislocation motion in single crystals, stress fields induced by dislocations, dislocation energy, force on dislocations (Peach-Koehler law), multiplication of dislocation (Frank-Read source).

2. Strengthening mechanisms: work hardening (Taylor equation), grain-boundary strengthening (Hall-Petch relation), solid solution strengthening, precipitation hardening, age-hardening.

3. Various stages of work hardening. Dynamic recovery, effect of stacking-fault energy. Shockley partial dislocations.

4. Basics of crystal plasticity theory: Taylor vs Sachs theory (introduction).

5. The crystallographic theory of twinning.

6. The phenomenological theory of martensitic transformations, occurring under either thermal or mechanical driving force.

7. The origin of crystallographic texture in metallic microstructures, the representation of texture and the experimental techniques to measure texture on a macro- or microscopic scale. The typical textures of steel and aluminium alloys (rolling, annealing and transformation textures).

8. The deformation microstructure: cell formation, deformation bands, shear bands, stored energy of plastic deformation

9. Thermally activated recovery mechanisms: recovery (formation of low-angle grain boundaries), recrystallization (nucleation and growth), JMAK equation, curvature driven grain growth (Gibbs-Thompson relation), Zener pinning.