MS&E #9 Phase diagrams
36 flashcards · Physics · by Kristóf Nagy
Proeutectoid cementite
A phase that forms along grain boundaries in a hypereutectoid alloy during cooling.
Primary phase
A phase that forms directly from the liquid phase during solidification.
Phase equilibrium
A state in which the phases in a system are in equilibrium with each other.
Phase diagram
A graphical representation of the phases present in a system as a function of temperature, pressure, and composition.
Phase
A homogeneous, mechanically separable portion of a system.
Peritectic reaction
A reaction in which a solid phase reacts with a liquid phase to form a different solid phase at a constant temperature.
Pearls
A microconstituent consisting of alternating layers of ferrite and cementite, formed during a eutectoid reaction.
Microconstituent
A small, distinct region within a microstructure, usually consisting of a single phase.
Metastable
A state in which a system is not in equilibrium, but does not spontaneously transform to the equilibrium state.
Liquidus line
A curve on a phase diagram that separates the liquid and solid phases.
Lever rule
A mathematical relation used to determine the amounts of different phases present in a two-phase system.
Isomorphous
Having the same crystal structure.
Invariant point
A point on a phase diagram where three phases coexist in equilibrium.
Austenite
The face-centered cubic (FCC) form of iron, which is stable at high temperatures.
Cementite
An intermetallic compound of iron and carbon, with the formula Fe3C.
Component
A substance that cannot be broken down into simpler substances by physical or chemical methods.
Congruent transformation
A phase transition in which the composition of the reactants and products is the same.
Intermetallic compound
A compound that forms when two or more metals combine chemically in a definite proportion.
Equilibrium
A state in which no net change is occurring in a system.
Intermediate solid solution
A solid solution that forms when two or more elements with dissimilar crystal structures mix.
Hypoeutectoid alloy
An alloy that contains less of the higher-melting component than the eutectic composition.
Eutectic phase
A solid phase that forms from the simultaneous crystallization of two or more liquids during a eutectic reaction.
Eutectic reaction
A reaction in which a liquid mixture solidifies to form two or more solid phases at a constant temperature.
Eutectic structure
A microstructure consisting of alternating plates or lamellae of two or more solid phases, formed during a eutectic reaction.
Eutectoid reaction
A reaction in which a single solid phase transforms into two or more solid phases at a constant temperature.
Ferrite
The body-centered cubic (BCC) form of iron, which is stable at low temperatures.
Free energy
The difference between the enthalpy and entropy of a system.
Hypereutectoid alloy
An alloy that contains more of the higher-melting component than the eutectic composition.
Gibbs phase rule
A rule that relates the number of independent variables (such as temperature, pressure, and composition) to the number of phases in a system.
Terminal solid solution
A solid solution that forms when one element dissolves in another element with the same crystal structure.
System
A collection of matter and energy.
Solvus line
A curve on a phase diagram that separates two solid phases.
Solubility limit
The maximum amount of a solute that can be dissolved in a solvent at a given temperature.
Solidus line
A curve on a phase diagram that separates the solid and liquid phases.
Tie line
A line connecting the compositions of two phases in equilibrium on a phase diagram.
Proeutectoid ferrite
A phase that forms along grain boundaries in a hypoeutectoid alloy during cooling.