Imperfection in Solids

such an idealized solid does not exist; all contain large numbers of various defects or

refers to a lattice irregularity having one or more of its dimensions on the order of an atomic diameter. Classification of crystalline imperfections is frequently made according to the geometry or dimensionality of the defect

responsible for reductions of gas pollutant emissions from

the simplest of the point one normally occupied but from which an atom is missing defects

the presence of vacancies increases the ___ (i.e., the randomness) of the crystal.

is an atom from the crystal that is crowded into an interstitial site—a small void space that under ordinary circumstances is not occupied.

Solids are like humans, they are not perfect. They also have ___

imperfection in/of solids

A ___ forms when, as the solute atoms are added to the host material, the crystal structure is maintained and no new structures are formed.

A solution is composed of two parts:

Impurity point defects are found in solid solutions, of which there are two types:

Appreciable quantities of a solute may be accommodated in this type of solid solution only when the difference in atomic radii between the two atom types is less than about 15%. Otherwise, the solute atoms create substantial lattice distortions and a new phase forms.

For appreciable solid solubility, the crystal structures for metals of both atom types must be the same.

The more electropositive one element and the more electronegative the other, the greater the likelihood that they will form an intermetallic compound instead of a substitutional solid solution.

Other factors being equal, a metal has more of a tendency to dissolve another metal of higher valency than to dissolve one of a lower valency.

impurity atoms fill the voids or interstices among the host atoms

two types of interstitial sites

the number of nearest neighbor host atom

___ have relatively high atomic packing factors, which means that these interstitial positions are relatively small.

the maximum allowable concentration of interstitial impurity atoms is low

Even very small impurity atoms are ordinarily larger than the interstitial sites, and as a consequence, they introduce some ___ on the adjacent host atoms

(wt%) is the weight of a particular element relative to the total alloy weight.