Material Science-Chapter 8

All Vocab from chapter 8

slip

: Plastic deformation as the result of dislocation motion; also, the shear displacement of two adjacent planes of atoms.

dislocation density

The total dislocation length per unit volume of material; alternatively, the number of dislocations that intersect a unit area of a random surface section.

lattice strain

Slight displacements of atoms relative to their normal lattice positions, normally imposed by crystalline defects such as dislocations, and interstitial and impurity atoms.

slip system

The combination of a crystallographic plane and, within that plane, a crystallographic direction along which slip (i.e., dislocation motion) occurs.

resolved shear stress

An applied tensile or compressive stress resolved into a shear component along a specific plane and direction within that plane.

critical resolved shear stress (r_crss)

The shear stress, resolved within a slip plane and direction, required to initiate slip

solid-solution strengthening

Hardening and strengthening of metals that result from alloying in which a solid solution is formed. The presence of impurity atoms restricts dislocation mobility.

strain hardening

The increase in hardness and strength of a ductile metal as it is plastically deformed below its recrystallization temperature.

cold working:

The plastic deformation of a metal at a temperature below that at which it recrystallizes.

recovery

The relief of some of the internal strain energy of a previously cold-worked metal, usually by heat treatment.

recrystallization

The formation of a new set of strain-free grains within a previously cold-worked material; normally, an annealing heat treatment is necessary.

recrystallization temperature

For a particular alloy, the minimum temperature at which complete recrystallization occurs within approximately 1 h.

grain growth

The increase in average grain size of a polycrystalline material; for most materials, an elevated-temperature heat treatment is necessary.

viscosity (𝜂)

The ratio of the magnitude of an applied shear stress to the velocity gradient that it produces—that is, a measure of a noncrystalline material's resistance to permanent deformation.

drawing (metals

A forming technique used to fabricate metal wire and tubing. Deformation is accomplished by pulling the material through a die by means of a tensile force applied on the exit side.

vulcanization

A nonreversible chemical reaction involving sulfur or another suitable agent in which crosslinks are formed between molecular chains in rubber materials. The rubber's modulus of elasticity and strength are enhanced.