mse 201 exam 3

eutectic reaction

upon cooling one liquid phase is transformed into two solid phases

Eutectoid reaction

upon cooling one solid phase transforms into two other solid phases

hypereutectoid alloy

An alloy with a greater concentration of solute than an alloy system that displays a eutectoid

hypoeutectoid alloy

For an alloy system displaying a eutectoid, an alloy for which the concentration of solute is less than the eutectoid composition.

intermetallic compound

A compound formed of two or more metals that has its own unique composition, structure, and properties

metastable

A nonequilibrium state that may persist for a very long time.

Bainite

a phase found in some steels and cast irons that forms at temperatures between those at which pearlite and martensite transformations occur (on the Time-Temperature transformation chart).

Martensite

a metastable carbon-iron alloy phase that is the product of a diffusionless transformation (occurs quickly and carbon does not have time to diffuse from FCC interstitials) from austenite. Forms a hard and brittle steel

Pearlite

a two phase microstructure found in some steels and cast irons; it results from the transformation of austenite of eutectoid composition and consists of alternate layers (or lamellae) of -ferrite and cementite. The transformation occurs due to diffusion (and often requires a significant amount of time to occur).

Eutectoid steel

a steel that has 0.76 wt% carbon and if cooled slowly has 100% pearlite

Pearlitic steel

a steel that has pearlite as one of it's microconstituents (typically has pearlite and alpha iron if hypoeutectoid or pearlite and cementite if hypereutectoid)

Spheroidite

microstructure found in steel alloys consisting of spherelike cementite particles within an a-ferritematrix. It is produced by an approximate elevated temperature heat treatment of perlite, bainite, or martensite and is relatively soft.

Tempered martensite

the microstructural product resulting from a tempering heat treatment of a martensitic steel. The microstructure consists of extremely small and uniformly dispersed cementite particles embedded within a continuous a-ferrite matrix. Ductility and toughness are enhanced significantly by tempering.

Annealing

heat and allow it to cool slowly, in order to remove internal stresses and toughen it.

austenitizing

heating steel to a temperature at which it transforms to austenite

full annealing

The pro-eutectoid component and course pearlite are formed in low and medium carbon steels that are to be plastically deformed or machined in order to make the material soft and ductile

normalizing

Decreases the size and creates a more uniform grain structure on steels that have been plastically deformed

Process Annealing

Used during fabrication procedures that require extensive plastic deformation to prevent fracture of the object as it is being formed.

stress relief

Reduces residual stresses due to plastic deformation during fabrication, non uniform cooling, phase transformation during cooling, etc.

Anion

A negatively charged ion

cation

A positively charged ion

octahedral position

critical number of 6, bigger than tetrahedral

tetrahedral position

critical number of 4, smaller than octahedral