Mse Ch 4

Front 1

diffusion

Back 1

A process of mass transport that involves the movement of one atomic species into another

Front 2

diffusion bonding

Back 2

The process by which two pieces are bonded or joined together by atomic mixing at the interface accomplished by solid state diffusion under conditions of high temperature and pressure

Front 3

diffusion coefficient

Back 3

The constant in the equation relating mass flux per unit area to the concentration gradient. It obeys an Arrhenius-type equation and as such is strongly temperature-dependent. This describes the ease of atomic or ionic motion in the solid state

Front 4

effective penetration distance

Back 4

The distance at which the concentration of a solute in a solid solution reaches a value of approximately the average of the surface concentration and the initial bulk concentration

Front 5

Fick's first law

Back 5

An equation which states that the mass flux per unit area of a diffusing species under steady-state conditions is proportional to the concentration gradient

Front 6

Fick's second law

Back 6

An equation which states that for non-steady-state conditions the rate of change of concentration with respect to time at a given location is proportional to the second derivative of concentration with respect to position

Front 7

Frenkel defect

Back 7

A defect in an ionic solid consisting of a vacancy/interstitial pair of the same ionic species. Due to size considerations, most of these involve cations

Front 8

Hume-Rothery rules

Back 8

A set of rules for the formation of substitutional solid solutions. They incorporate relative sizes, bond character, and electronegativity of the atomic species being considered

Front 9

impurity

Back 9

Any atom or ion species that differs from the host or solvent species. While considered to be defects, these may confer desirable properties on the solid solution

Front 10

impurity diffusion

Back 10

The diffusion of an impurity species at very low concentrations within the solvent or host material

Front 11

interstitial

Back 11

A point defect consisting of an atom or ion that is located in the interstices of the structure under consideration; may be either the same or a different species than the solvent

Front 12

interstitial solid solution

Back 12

A solid solution in which atoms or ions of a foreign species are located in the interstitial positions

Front 13

point defect

Back 13

A "mistake" in the material that involves a single atom, ion, lattice site, or interstitial position. For example, if an atom is missing at a regular lattice site, it is said to have been formed

Front 14

Schottky defect

Back 14

Small cation and anion vacancy clusters that are formed in ionic solids. The cation/anion ratio in these clusters is adjusted to maintain electroneutrality

Front 15

self-diffusion

Back 15

The mechanism by which a species diffuses in itself

Front 16

solute

Back 16

An atom or ion species that is dissolved in a host or solvent

Front 17

solvent

Back 17

The host species for a solute

Front 18

substitutional solid solution

Back 18

A solution formed by substituting species B directly for species A on the lattice sites normally occupied by A

Front 19

vacancy

Back 19

A missing atom or ion at a lattice site that would normally be occupied