Shared Flashcard Set

Details

Material Science
Test 2 Flashcards
37
Chemical Engineering
Undergraduate 3
10/15/2010

Additional Chemical Engineering Flashcards

 


 

Cards

Term

The maximum allowable flaw size:

 

ac

Definition
[image]
Term

plane strain fracture toughness:

 

KIc

Definition
[image]
Term
dislocation density:
Definition
the total dislocation length per unit volume or, equivalently, the number of dislocations that intersect a unit area of a random section.
Term
Eutectic reaction:
Definition
a liquid phase transforms
isothermally to two different solid phases upon cooling.
Term
  • Solidus line:
  • Liquidus line:
  • Solvus line:
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
intergranular
fracture:
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

peritectic reaction:

 

Definition
Upon heating, one solid phase transforms into a liquid phase and another solid phase.
Term

[image]

 fration of pearlite:

 

Wp

Definition
[image]
Term
Lattice strain:
Definition
Slight displacements of atoms relative to their normal
lattice positions, normally imposed by crystalline defects.
Term
Slip system:
Definition

The combination of a
crystallographic plane and, within
that plane, a crystallographic direction along which slip

(i.e., dislocation motion) occurs.

Term
Gibbs phase rule:
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
In Kenetics ΔGv is:
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
[image]
Term
Frenkel defect:
Definition
A type of defect in ceramics that involves a cation–vacancy and a
cation–interstitial pair.
Term
Schottky defect:
Definition
A type of defect found within a ceramic that involves a cation vacancy–anion vacancy
pair.
Term
tetrahedral positions:
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
Percent cold work (%CW)
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

the nucleation rate

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
Bainite:
Definition

is composed of a ferrite matrix and elongated particles of Fe3C.

It occurs at temperatures
below those at which pearlite forms.

Term
spheroidite:
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
martensite:
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

[image]

 

[image]

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
Rock Salt Structure:
Definition

FCC Like Coordination#:6

[image]

Term
Cesium Chloride Structure:
Definition

BCC Like Coordination#:8

[image]

 

Term
Zinc Blende Structure:
Definition

 Diamond Like Coordination#:4

[image]


Supporting users have an ad free experience!