Term
| Crystalline Defect examples |
|
Definition
point defects (thermal vibration)
Linear defects (dislocations)
Planar defects
Complete lacking in crystalline order (amorphous) |
|
|
Term
| Solid solution(chemical imperfection) |
|
Definition
Commercial metal alloys : solid solution
A. Substitutional & B. interstitial solid solution |
|
|
Term
| Substitutional solid solution |
|
Definition
Hume-Rothery rules (for substitutional solid solution)
1.Less than about 15% difference in atomic radii
2.The same crystal structure
3.Similar electronegativities (ability of the atom to attract electron)
4.The same valence |
|
|
Term
| Interstitial solid solution |
|
Definition
Smaller atom simply to fit into spaces
Occur when atom sizes differ greatly
Energetically unstable structure
Produces considerable local strain (C in alpha-Fe) |
|
|
Term
|
Definition
zero-dimensional imperfection
structural defects (independently of chemical impurities)
Defects with the crystalline point lattice
Two types:
1.Vacancy
2.interstitial |
|
|
Term
|
Definition
Quantitative designation
Displacement vector (a vector to close the loop)
Magnitude of the structural defect |
|
|
Term
|
Definition
| burgers vector is perpendicular to the dislocation line |
|
|
Term
|
Definition
Spiral stacking of crystal planes around the dislocation line
Burgers vector is parallel to the dislocation line |
|
|
Term
|
Definition
Most linear defects in actual material
Both edge and screw dislocation |
|
|
Term
| Numerous forms of planner defects |
|
Definition
1.Twin boundary
-Structurally mirror images
-Deformation (hcp), annealing (fcc)
2.Surface defect
-Surface atoms are different from bulk atoms
3.Grain boundary
-Region between two crystals or grains |
|
|
Term
| Noncrystalline solids 3 Dimensional imperfections) |
|
Definition
1.Oxide glass
2.Amorphous semiconductor
3.Amorphous metal |
|
|
Term
|
Definition
-Rapid cooling silicate
-Random stacking
-Zachariasen model |
|
|
Term
|
Definition
-Economic advantage
-Complex electronic property |
|
|
Term
|
Definition
-Metallic glasses, Bernal model
-Rapid cooling of liquid metal to prevent crystallization (1°C/s)
-Uniformity of the noncrystalline structure eliminates the grain boundary (High strengths and excellent corrosion resistance) |
|
|
