Physical metallurgy: phase diagram, type 1 to 3

Solid Solution

Mixtures of two or more metals where one metal (solute) is dissolved in another (solvent) without forming a new compound.

Substitutional Solid Solution

A type of solid solution where solute atoms replace solvent atoms in the crystal lattice.

Interstitial Solid Solution

A type of solid solution where solute atoms occupy interstitial spaces between solvent atoms in the crystal lattice.

Phase Diagram

A graphical representation of the phases present in an alloy system as a function of temperature and composition.

Liquidus Line

The line in a phase diagram that indicates the temperatures at which solidification begins.

Solidus Line

The line in a phase diagram that indicates the temperatures at which solidification is complete.

Tie Line

A horizontal line drawn at a specific temperature in a phase diagram to determine the compositions of phases present.

Lever Rule

A method used to calculate the relative amounts of different phases present in a two-phase region of a phase diagram.

Eutectic Reaction

A reaction where a liquid phase transforms into two solid phases at a constant temperature.

Eutectic Point

The composition and temperature at which the eutectic reaction occurs.

Coring

The phenomenon where solidified alloys have a composition gradient, with the center being richer in one component.

Homogenization

The process of equalizing the composition of an alloy, often through heat treatment.

Diffusion

The movement of atoms within a solid, which can lead to changes in composition and phase distribution.

Vacancy Mechanism

A diffusion mechanism where solute atoms move into vacant lattice sites.

Interstitial Mechanism

A diffusion mechanism where solute atoms move into interstitial spaces in the lattice.

Atom Interchange Mechanism

A diffusion mechanism involving direct interchange between adjacent atoms.

Solvus Line

The line in a phase diagram that indicates the maximum solubility of one component in another at various temperatures.

Hypoeutectic Alloy

An alloy with less than the eutectic composition.

Hypereutectic Alloy

An alloy with more than the eutectic composition.

Cooling Rate

The rate at which an alloy is cooled, affecting its microstructure and properties.

Age Hardening

A heat treatment process that increases the strength and hardness of an alloy through precipitation of a second phase.

Solution Treatment

A heat treatment process to dissolve excess solute and create a homogeneous solid solution before quenching.

Aging Process

The period during which a supersaturated solid solution is held at a specific temperature to allow precipitation of a second phase.

Congruent Melting Phase

A phase that melts and solidifies at a constant temperature without changing composition.

Eutectic Temperature

The temperature at which the eutectic reaction occurs, leading to the formation of a fine mixture of solid phases.

Microstructure

The structure of a material as observed at the microscopic level, influencing its mechanical properties.

Thermal Analysis

A method for determining phase changes in alloys by measuring temperature changes during solidification.

Metallographic Methods

Techniques used to examine the microstructure of metals and alloys, often involving heating and cooling samples.

X-ray Diffraction

A technique used to identify changes in crystal structure and lattice dimensions in alloys.

Coring Structure

A structure resulting from nonequilibrium cooling, characterized by a composition gradient within the solid.

Homogeneous Alloy

A solid solution with uniform composition throughout the material.