New Materials

Front 1

Steady State Diffusion Equation

Back 1

J=-D(c2-c1/x2-x1)

Front 2

Diffusion and Temperature

Back 2

D=D.exp(Qd/RT)

Front 3

Critical Resolve Shear Stress

Back 3

The minimum shear stress required to initiate slip. Determines when yielding occurs

Front 4

Methods for Strengthening

Back 4

Reduce grain size, solid solution strengthening, cold working

Front 5

Reducing Grain Size

Back 5

-Smaller grain size means that there are more barriers to slip

Front 6

Solid Solution Strengthening

Back 6

-Impurity atoms distort the lattice and generate lattice strains

-These stains oppose the outside forces acting on the material

Front 7

Cold Working

Back 7

-Deformation at room temperature

-Dislocations entangle with each other

-Dislocation density increases

Front 8

Recovery

Back 8

Reduction of dislocation density

Front 9

Recrystallization

Back 9

*New grains form that:

-have low dislocation densities

-are small in size

-consume and replace parent cold worked grains

Front 10

Small Grains

Back 10

Relatively strong and tough at low temperatures

Front 11

Large Grains

Back 11

Good creep resistance at relatively high temperatures

Front 12

Fracture Toughness

Back 12

A measure of a material's resistance to brittle fracture when a crack is present

Front 13

Three steps of creep

Back 13

Primary or Transient Creep, Secondary or Steady-stat creep, and Tertiary creep

Front 14

Creep: Temperature Dependence/Secondary

Back 14

With either increasing stress or temperature,
the following will be noted: (1) the instantaneous strain at the time of stress application
increases, (2) the steady-state creep rate increases, and (3) the rupture lifetime decreases

Front 15

Larson Miller Parameter

Back 15

T(C+log(tr))

Front 16

Ductile Fracture

Back 16

-Necking, void nucleation, void growth and coalescence, shearing at surface, fracture

-large deformation

Front 17

Brittle Fracture

Back 17

-Many pieces

-Small deformations

Front 18

Intergranular

Back 18

Crack propagation along grain bondaries

Front 19

Transgranular

Back 19

Fracture cracks pass through grains

Front 20

Fatigue strength

Back 20

The stress level at which failure will occur after some number of cycles

Front 21

Fatigue Life

Back 21

The number of cycles to cause failure at a specified stress level

Front 22

Case Hardening

Back 22

Accomplished by a carburizing or nitrogenous atmosphere at elevated temperature

Front 23

Primary/transient creep

Back 23

typified by a continuously decreasing creep rate; that is, the slope of the curve decreases with time. This suggests that the material is experiencing an increase in creep resistance or strain hardening (Section 8.11)—deformation becomes more difficult as the material is strained.

Front 24

Secondary/Steady State

Back 24

the rate is constant; that is, the plot becomes linear. This is often the stage of creep
that is of the longest duration. The constancy of creep rate is explained on the basis of a
balance between the competing processes of strain hardening and recovery, recovery
(Section 8.12) being the process by which a material becomes softer and retains its ability to experience deformation

Front 25

Tertiary Creep

Back 25

there is an acceleration of the
rate and ultimate failure. This failure is frequently termed rupture and results from
microstructural and/or metallurgical changes—for example, grain boundary separation, and the formation of internal cracks, cavities, and voids

Front 26

Hypoeutectic

Back 26

Hypoeutectic - an alloy to the left of the eutectic composition, but to the right of the point where the solvus and solidus lines corresponding to the left composition meet, as shown below.

Front 27

Hypereutectic

Back 27

Hypereutectic - an alloy to the right of the eutectic composition, but to the left of the point where the solvus and solidus lines corresponding to the right composition meet, as shown below.

Front 28

Eutectic Reaction

Back 28

Upon cooling, a liquid phase is transformed into the two solid phases alpha and beta

Front 29

Eutectoid

Back 29

A solid phase turns into two solid phases at a single temperature

Front 30

Peritectic Reaction

Back 30

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

Front 31

Ferrite

Back 31

-iron-carbon phase diagram

-pure iron, upon heating, experiences two changes in crystal structure before it melts.

-at room temperature the stable form, called ferrite, has a BCC structure

Front 32

Austenite

Back 32

Ferrite experiences a polymorphic transformation to FCC

Front 33

Cementite

Back 33

iron carbide, 6.7 wt% C

Front 34

Solubility Limit

Back 34

Solubility limit: The maximum concentration of solute atoms that may dissolve in the solvent to form a solid solution.