Imperfections Flashcards
Is a pollutant-reducing device that is located in a car’s exhaust system
Catalytic Converter
Refers to a lattice irregularity whose dimensions are in the order of 1 Atomic Diameter
Crystalline Defect
True or False. There is what we call a perfect crystal
False
Types of Imperfections
Point Defects
Line Defects
Area Defects
Types of Point Defects
Vacancy Atoms
Interstitial Atoms
Substitutional Atoms
An example of a line defect
Dislocation
An example of an area defect
Grain Boundaries
The simplest point defect
Vacancy
One that is normally occupied from which an atom is missing
Vacancy
True or False. All crystalline solids contain vacancies
True
vacant atomic sites in a structure
Vacancy
are extra atoms positioned between atomic sites
Self-Interstitials
What do you call the constant k
Boltzmann’s Constant
What is the value of the Boltzmann’s Constant
1.38x10^-23
Is an atom from the crystal that is crowded into an interstitial site
Self-Interstitial
They have impurity atoms that have been added intentionally to impart specific characteristics to the material
Alloy
What is Nv?
Equilibrium Number of Vacancies
What is the formula for Nv
Nv=N exp (-Qv/kT)
Results from the addition of impurity atoms to a metal
Solid Solution
Represents the element or compound that is present in the greatest amount
Solvent
Another term for solvent atoms
Host Atoms
Is used to denote an element or compound present in minor concentration
Solute
They have solute or impurity atoms replace or substitute the host atoms
Substitutional
Conditions for substitutional solid solution
Atomic Size Factor
Crystal Structure
Electronegativity
Valences
is also called the concentration of an alloy in terms of its constituent elements
Composition
Is the weight of a particular element relative to the total alloy weight
Weight Percent
Number of moles of an element in relation to the total moles of the elements in the alloy
Atom Percent
Is a linear or one dimensional defect around which some of the atoms are misaligned
Dislocation
It is a linear defect that centers on the line that is defined along the end of the extra half-plane of atoms
Edge Dislocation
The line where the edge dislocation is centered around
Dislocation Line
May be though of as being formed by a shear stress that is applied to produce a distortion
Screw Dislocation
Exhibit components of both edge and pure screw dislocations
Mixed Dislocations
The magnitude and direction lattice distortion associated with a dislocation is expressed in terms of ___
Burgers Vector
Are boundaries that have two dimensions and normally separate regions of the materials that have different crystal structures
Interfacial defects
Most obvious boundaries
External Surface
Boundary separating two small grain or crystals having different crystallographic orientations in polycrystalline materials
Grain Boundaries
Exist in multiphase materials wherein different phase exists on each side of the boundary
Phase Boundaries
Is a special type of grain boundary across which there is a specific mirror lattice symmetry
Twin Boundary
Are line defects
Dislocations
extra half-plane atoms inserted in a crystal structure
Edge Dislocations
Spiral planar ramp resulting from shear deformation
Screw Dislocation
Measure of Lattice Distortion
Burgers Vector
