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19 Cards in this Set
- Front
- Back
diffusion
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A process of mass transport that involves the movement of one atomic species into another
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diffusion bonding
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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
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diffusion coefficient
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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
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effective penetration distance
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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
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Fick's first law
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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
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Fick's second law
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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
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Frenkel defect
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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
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Hume-Rothery rules
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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
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impurity
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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
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impurity diffusion
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The diffusion of an impurity species at very low concentrations within the solvent or host material
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interstitial
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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
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interstitial solid solution
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A solid solution in which atoms or ions of a foreign species are located in the interstitial positions
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point defect
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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
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Schottky defect
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Small cation and anion vacancy clusters that are formed in ionic solids. The cation/anion ratio in these clusters is adjusted to maintain electroneutrality
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self-diffusion
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The mechanism by which a species diffuses in itself
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solute
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An atom or ion species that is dissolved in a host or solvent
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solvent
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The host species for a solute
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substitutional solid solution
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A solution formed by substituting species B directly for species A on the lattice sites normally occupied by A
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vacancy
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A missing atom or ion at a lattice site that would normally be occupied
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