Crystalline Structure Flashcards
What is the difference between crystalline and amorphous materials?
A crystalline material has long-range order while an amorphous material does not.
What are the three main types of Bravais lattice in metals?
Body centred cubic, Face centred cubic and Hexagonal close-packed.
What is a motif?
A motif is the atomic arrangement at the lattice point.
What is the atomic packing factor?
The fraction of space taken by atoms
What is Polymorphism?
when a material has more than one crystal structure
What is Allotropy?
A specific type of polymorphism which occurs in the solids of purely one element
What is Anisotropy?
To not have the same properties in different directions
What is Isotropy?
To have the same properties in different directions
What are Vacancies?
Where there is a space where an atom should theoretically be.
What are Self-Interstitials?
Where an atom sits in a void between normal atomic sites.
What is the Solvent?
Is the host material/lattice
What is the Solute?
Is the impurity
What is Substitutional?
Impurity atom replaces host atom.
What is Interstitial
Impurity atoms fill voids or interstices among host atoms
What are the types of linear defects?
1) Edge, A linear defect centred where there is an extra half plane of atoms and there is localised lattice distortion.
2) Screw, A shear distortion in the lattice such that shear and unsheared parts of the crystal are defined by a line.
What are external surface planar defects?
Where the surface of a material has a high energy due to them not being able to bond on one side.
What are grain boundary planar defects?
As not all atoms are fully bonded at grain boundaries the is an energy associated with the grain boundary which increases as misorientation increases.
What are twin boundary planar defects?
A specific type of grain boundary that has mirror-like symmetry.
What are stacking fault planar defects?
Where the normal sequence of stacking planes is disrupted.
What are phase boundary planar defects?
Where there are two different phases either side of the boundary.
What are Burgers Vectors?
Burgers vectors defines a magnitude and direction of lattice distortion associated with dislocations.
What is Slip?
A tendency of a material’s particles to undergo plastic deformation dues to a dislocation motion within the material. Occurs in the closest packed planes as it is the lowest energy route.
What are Slip systems?
A combination of close packed planes and in the most close-packed direction
What is Miscibility?
A scale of how substances combine to form a homogenous solution without precipitates.
Draw the following on cubic unit cells, [001], [211], [120], (110), (201), (111).
look them up
Draw the following on hexagonal prism unit cells (0001) , (10-11),(1-100), (0-111).
look them up on practice exams
What are BCC, FCC, and HCP’s axial relationships and interaxial angles?
BCC: a=b=c, α=β=γ=90
FCC: a=b=c, α=β=γ=90
HCP: a=b (not) c , α=β=90 and γ=120
