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MSE Ch 4
Materials Science and Engineering - Imperfections in the atomic arrangements
| Term | Definition |
|---|---|
| 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
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