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MSE Ch 4

Materials Science and Engineering - Imperfections in the atomic arrangements

TermDefinition
What are the 3 types of defects? line, point, surface
Based on bond strength alone, most materials SHOULD be much ____(stronger/weaker) than they are. stronger
T or F? Materials usually fail by bonds breaking. False
What is the difference between impurities and dopants? dopants are put in on purpose
A ___ is produced when an atom is missing. vacancy
Vacancies are introduced into metals and alloys during ___ at ___ temperatures or as a consequence of radiation damage. solidification, high
Concentration of vacancies ___(increases/decreases) exponentially as temperature is increased. increases
The Arrhenius equation for vacancies is ___. n_v = ne^(-Q_v/RT)
In n_v = ne^(-Q_v/RT), n_v = ___. number of vacancies per cm³
n_v = ne^(-Q_v/RT), n = ___. number of atoms per cm³
n_v = ne^(-Q_v/RT), Q = ___. activation energy
n_v = ne^(-Q_v/RT), R = ___. ideal gas constant = 1.987 (cal/mol-K) or 8.31 (joules/mol-K)
n_v = ne^(-Q_v/RT), T = ___. Kelvin
Slip most easily occurs along a ___. dislocation
Name the 3 types of dislocations. edge, screw, mixed
Strength of a material depends on the force required to ___, not the bond energy. make a dislocation move (slip)
An edge dislocation is ___. an extra plane of atoms
The deformation direction is labeled with a ___ vector. Burgers
For edge dislocations, Burgers vector is ___ to the dislocation line. perpindicular
The Burgers vector is the direction of the ___ force. shear
An edge dislocation is so called because when slip occurs, ___. it creates an edge on the surface
A screw dislocation is a ___. ramped step
For screw dislocations, Burgers vector is ___ to the dislocation line. parallel
When a dislocation moves it is called ___. slip
Slip is easiest along ___ in the ___ directions. close packed planes, close packed
Combinations of close packed planes and close packed directions are called ___. slip systems
___ metals are fairly strong, yet still ductile. FCC
___ metals are stronger, but not very ductile. BCC
___ metals are strongest, but very brittle. HCP
T or F? The more ductile a material, the less strength and vice versa. True
T or F? Dislocations weaken a material. False
Frank Read Source says that applying force to a material ___(increases/decreases) the number of dislocations. increases
T or F? Point defects make a material weaker. False
Name the types of point defects. vacancy, interstitial, substitutional, interstitialcy
What are the types of interstitialcy defects? Frenkel, Schottky
Frenkel defects are ___. when ions are in the wrong spot
Schottky defects are ___. vacancies of a pair of ions, one anion and one cation
With Schottky defects, the overall charge ___. remains neutral
Which defects are in ceramics only? Frenkel and Schottky
T or F? Dislocations can cross grain boundaries. False
Larger grain size results in ___(increased/decreased) strength. decreased
The Hall-Petch equation calculates ___ and is defined as ___. yield strength, σ_y = σ_0 + K/√d
For the Hall-Petch equation σ_y = σ_0 + K/√d, σ_0 = ___. a constant for the metal
For the Hall-Petch equation σ_y = σ_0 + K/√d, K = ___. a constant for the metal
For the Hall-Petch equation σ_y = σ_0 + K/√d, d = ___. average diameter of the grains
The equation for ASTM grain size calculation is ___. N = 2^n-1
N = the number of grains per ___ at a magnification of ___. inch, 100
Amorphous structures are called ___. glass
Amorphous metals are also called ___. liquid metals
T or F? There are no slip planes in glass. True
Amorphous metals are made by ___ which makes it hard for metals to crystalize. alloying with many different sizes of atoms
The brand name for liquid metal is called ___. vitreloy
Created by: drjolley