Term
The maximum allowable flaw size:
ac |
|
Definition
|
|
Term
plane strain fracture toughness:
KIc |
|
Definition
|
|
Term
|
Definition
| the total dislocation length per unit volume or, equivalently, the number of dislocations that intersect a unit area of a random section. |
|
|
Term
|
Definition
a liquid phase transforms
isothermally to two different solid phases upon cooling. |
|
|
Term
|
Definition
- Line at which solidification is complete upon equilibrium cooling.
- boundary separating liquid and liquid + solid phase regions
- The locus of points on a phase diagram representing the limit of solid solubility as a function of temperature.
|
|
|
Term
|
Definition
| crack propagation along grain boundaries. (as opposed to transgranular) |
|
|
Term
resolved shear stress:
τR |
|
Definition
[image]
φ angle between the normal to the slip plane and the applied stress direction
λ the angle between the slip and stress directions |
|
|
Term
|
Definition
| Upon heating, one solid phase transforms into a liquid phase and another solid phase. |
|
|
Term
[image]
fration of pearlite:
Wp |
|
Definition
|
|
Term
|
Definition
Slight displacements of atoms relative to their normal
lattice positions, normally imposed by crystalline defects. |
|
|
Term
|
Definition
The combination of a
crystallographic plane and, within
that plane, a crystallographic direction along which slip
(i.e., dislocation motion) occurs. |
|
|
Term
|
Definition
P + F = C + N
P: # of phases present
F: # of degrees of freedom
C: # of componets in system
N: # of noncompositional variable
(like T, P, or V) |
|
|
Term
|
Definition
The volume free energy change. It is the driving force for the solidification
transformation, and its magnitude is a function of temperature. |
|
|
Term
In Kenetics what is:
Tm & R* |
|
Definition
Tm: The equilibrium solidification temperature
R*: Critical Radius
•Below which embryo dissolves
•Above which nucleus forms |
|
|
Term
Avrami equation:
what is it used for? |
|
Definition
[image]
To determine mass-fraction of
phase transformation with respect to time. |
|
|
Term
Describe the transformation of Austenite into:
Pearlite
Bainite
Martensite
& Tempered Martensite |
|
Definition
|
|
Term
|
Definition
A type of defect in ceramics that involves a cation–vacancy and a
cation–interstitial pair. |
|
|
Term
|
Definition
A type of defect found within a ceramic that involves a cation vacancy–anion vacancy
pair. |
|
|
Term
|
Definition
Interstitial positions that involve 4 atoms. (three in one plane, and a single one in the adjacent plane)
Coordination #: 4 |
|
|
Term
The minimum shear stress required to initiate slip:
What's the equation for the magnitude of the applied stress required to initiate yielding? |
|
Definition
critical resolved shear stress:
τcrss
[image] |
|
|
Term
|
Definition
[image]
Where A0 is the original area of the cross section that experiences deformation, and Ad is the area after deformation. |
|
|
Term
| What is a cup-and-cone fracture & what are the associated stages? |
|
Definition
Decribes the physical stages of how ductile fracture ocurrs.
(a) Initial necking. (b) Small
cavity formation. (c) Coalescence of cavities to form a crack. (d) Crack propagation. (e) Final shear fracture at a 45º angle relative to the tensile direction. |
|
|
Term
| Describe a brittle fracture. |
|
Definition
| Takes place without any appreciable deformation, and by rapid crack propagation. The direction of crack motion is nearly perpendicular to the directionof the applied tensile stress and yields a relatively flat fracture surface. |
|
|
Term
The total free energy change regarding the solidification of a pure material.
ΔG |
|
Definition
[image]
solidification ocurrs when ΔG is negative. |
|
|
Term
Number of stable nuclei n*
(having radii greater than r*) |
|
Definition
[image]
where the constant is related to the total number of nuclei of the solid phase. |
|
|
Term
| The frequency at which atoms from the liquid attach themselves to the solid nucleus vd |
|
Definition
[image]
where Qd is the activation energy for diffusion and. It & K2 are temperature-independent constants. |
|
|
Term
|
Definition
[image]
K3 is the number of atoms on a nucleus surface. |
|
|
Term
| The growth rate of a particle Ġ |
|
Definition
[image]
where Q (the activation energy) and C are independent of temperature. |
|
|
Term
|
Definition
is composed of a ferrite matrix and elongated particles of Fe3C.
It occurs at temperatures
below those at which pearlite forms. |
|
|
Term
|
Definition
Pearlite or Baindite heated below eutictic temprature for a significant amount of time. Fe3C phase appears as sphere-like particles embedded in a continuous
α phase matrix. |
|
|
Term
|
Definition
is formed when austenitized
iron–carbon alloys are quenced such-that the rate is rapid enough to prevent
carbon diffusion.
(is competitive with pearlite and bainite) |
|
|
Term
Stress ratio R:
Stress amplitude σa: |
|
Definition
|
|
Term
For Iron-Carbon Alloys
arange the microstructres in order from least to most strong
& then
least to most ductile. |
|
Definition
Spheroidite < Coarse pearlite < Fine pearlite < Bainite < Tempered martensite < Martensite
Ductility is arranged in reverse order. |
|
|
Term
|
Definition
FCC Like Coordination#:6
[image] |
|
|
Term
| Cesium Chloride Structure: |
|
Definition
BCC Like Coordination#:8
[image]
|
|
|
Term
|
Definition
Diamond Like Coordination#:4
[image]
|
|
|
