Material science chapter 8

Graphical representations showing phases (solid, liquid, gas) in a material at different temperatures, pressures, and compositions.

Conditions in phase diagrams assumed to result from slow cooling, allowing phases to reach a state where their properties are balanced.

A thermodynamic relationship that predicts the number of phases that can exist in equilibrium, considering the number of components and degrees of freedom in a system.

Variables like temperature and pressure that can change without a phase change in equilibrium.

Graphs that plot temperature changes over time when molten metal cools.

Temperature and pressure point where three phases (solid, liquid, and gas) coexist in equilibrium.

Transformation of a material from one phase (like solid) to another (liquid).

Pure metal cooling shows a flat region on its cooling curve when the liquid transforms to solid (liquid to solid phase change).

Pure metals solidify at a specific temperature.

Alloys solidify over a range of temperatures.

Period of constant temperature during solidification. Happens in pure metals.

Mixture of two phases existing at the same time in a cooling curve's plateau.

Generated from cooling curves at different compositions.

System with two components (like Cu-Ni), used to create phase diagrams.

An alloy system where two components are completely soluble in each other, both in liquid and solid states.

The line on a phase diagram showing the start of solidification.

The line on a phase diagram that shows the completion of solidification.

A line on a phase diagram connecting the liquid and solid phases in a mixture region.

A method to determine the amount of each phase in a mixture, based on the tie-line.

Solidification that deviates from equilibrium conditions, often due to fast cooling.

A microstructure in a solid where different regions have different compositions, often found from rapid cooling.

A heat treatment done to eliminate cored structures and to produce a more uniform microstructure.

A system where two components have limited solid solubility, creating a mixture of two solid phases at a specific temperature (eutectic point).

The alloy with the lowest melting point in a binary eutectic system.

Solid phases at the ends of the phase diagram, representing the maximum solubility of one component in the other.

The specific ratio of components in a binary eutectic system that forms the eutectic alloy.

An alloy in a binary eutectic system with less than the eutectic composition of the less soluble element.

An alloy in a binary eutectic system with more than the eutectic composition of the less soluble element.

The transformation of a liquid alloy directly into two solid phases upon cooling at the eutectic temperature.

The solid phase present in alloys that are hypoeutectic or hypereutectic, forming before the eutectic reaction.

A specific point on a phase diagram where the temperature and composition are fixed, and three or more phases coexist in equilibrium.

The invariant point on a phase diagram where a peritectic reaction occurs.

During a peritectic reaction, a liquid phase and a solid phase react to form a new solid phase. The new solid phase often surrounds the initial solid, creating a diffusion barrier.

A layer that restricts the movement of atoms, hindering further reactions or homogenization within the material.

The uneven distribution of elements within the solid phase formed during a peritectic reaction, due to the diffusion barrier created.

A process where a molten material is cooled down quickly, preventing complete diffusion and homogenization.

The newly formed solid phase in a peritectic reaction completely encloses the initial solid, creating a diffusion barrier.

A reaction where a liquid phase transforms into a solid phase and another liquid phase. This occurs when two liquids are immiscible, meaning they don't mix.

A phase that exists at the ends of a phase diagram. It represents the pure components of the system.

A phase that exists within a specific composition range in a phase diagram. It's not a pure component but a combination of the original components.

An intermediate phase (3Al2O3.2SiO2) formed in the Al2O3-SiO2 system, combining aluminum oxide and silicon dioxide.

A compound that melts directly into a liquid at a single temperature, without decomposition.

A compound that decomposes into different phases before melting entirely.

The degree to which a bond is ionic or covalent, determined by the electronegativity difference between the elements involved.

Intermediate compounds can be congruent or incongruent melting. Congruent compounds melt directly into a single liquid phase, while incongruent compounds decompose into other phases before melting.