Full Revision Flashcards
Hall Petch Equation?
deltayield= deltao + ky*d^-1/2
%CW
(Ao-Ad/Ao)x100
What is a Phase Diagram?
Is a representation of the relationships between temperature and the compositions and the quantities of phases in equilibrium.
Between the liquidus line & solidus line?
Island of solid material in liquid material
Lever Rule
S/S+R= (Calpha-Co/Calpha-Cl)
Effecting of Heating after Cold work: Recovery Stage
Allows dislocations to “move” and increases the possibility of annihilation => lowering dislocation density
Effect of Heating after cold work: Recrystallization Stage
New grains are formed that:
- have a small dislocation density
- are small
- consume cold-worked grains
Rolling metal is a forming technique:
that involves decreasing the thickness of the material.
Extruding metal is a forming technique:
that involves pushing a material through a small orifice.
Forging metal is a forming technique:
that involves hammering the material in shape.
Diffusion of atoms from one metal into another metal is known as:
interdiffusion, or impurity diffusion.
An isotropic material property is a material property that is
the same in all directions.
Which bond is directional?
Covalent bonds.
Coordination number, unit number of atoms and atomic packing factor of BCC
Coordination number: 8
Unit number:
N = Ni + Nf/2 + Nc/8 = 2
A crystalline defect refers to:
A lattice irregularity having one or more of its dimensions on the order of an atomic diameter.
Necessity of Vacancies in metals:
The presence of vacancies increases the entropy of the crystal.
What is a self-interstitial?
An atom from the crystal that is crowded into an insterstitial site, a small void space that under ordinary circumstances is not occupied.
What does a interstitial introduce in a metal?
interstitual introduces relatively large distortions in the surrounding lattice because the atom is substantially larger than the interstitial position in which it is situated. Consequently, the formation of this defect is not highly probable, and it exists in very small concentrations that are significantly lower than for vacancies.
Two types of impurities in solid solutions?
substitutional and interstitial
Substitutional impurity(metals):
Solute or impurity atoms replace or substitute for the host atoms.
The 4 factors that determine how successful an impurity dissolves in a metal host. (Hume-Rothery Rules).
- Atomic size factor
- Crystal Structure
- Electronegativity factor
- Valences
FCC:
Face-centered cubic crystal structure
Atoms located at each of the corners and the centers of all the cube faces.
Single Crystal:
When the periodic and repeated arrangement of atoms is perfect or extends throughout the entirety of the specimen without interruption.
Grain Boundary:
some atomic mismatch within the region where two grains meet.
Texture:
When the grains in a polycrystalline have a preferential crystallographic orientation.
Amorphous solid:
When a solid has a noncrystalline structure.
Their structure resembles that of a liquid.
Three main metal crystal structures:
FFC: Face-centered cubic
BCC: Body-centered cubic
HCP: Hexagonal close-packed
FCC cube edge length a:
a= 2R* Sqrt[2]
Coordination number,number of atoms and atomic packing factor in FCC?
Coordination number = 12
N = Ni + Nf/2 + Nc/8 = 4
APF = 0.74
Coordination number:
number of nearest-neighbour or touching atoms of each atom.
Atomic Packing Factor(APF):
The APF is the sum of the sphere volumes of all atoms within a unit cell divided by the unite cell volume.
APF= Volume of atoms in a unit cell/ total unit cell volume
BCC:
Body-centered structure
Atoms located at all eight corners and a single atom at the cube center.
BCC unit cell length a:
a= 4R/sqrt[3]
Rule of Mixtures?
Sum of Modulus * percentage composition
