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Liquidus, Solidus, Solvus, and Eutectic

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Quick
The liquidus is represented by a line on a phase diagram that separates a liquid phase from a solid + liquid phase region. A system must be heated above the liquidus temperature to become completely liquid. The liquid system begins to solidify when the temperature cools to the liquidus temperature.
The solidus is represented by a line on a phase diagram that separates a solid phase from a solid + liquid phase region. The system is not completely solid until it cools below the solidus temperature.
The solvus is represented by a line on a phase diagram that separates a solid phase from a solid1 + solid2 phase, where solid1 and solid2 are different microstructures.
The eutectic is represented by the horizontal line in a eutectic binary phase diagram, connecting the intersections of the solidus and solvus lines from both sides. The eutectic temperature also is where the liquidus lines for both components meet.

Note: for every instance above in which the word "solid" is stated, it is implied that it can represent solid1 or solid2.


Details

The diagram used to represent these lines is a eutectic binary phase diagram.

α solid1 β solid2 L liquid

Liquidus, solidus, and solvus temperatures will correspond to a specific composition of interest. In this case, the composition of interest is 10% B. B is the component that is at the other end of the phase diagram that is cut off. Therefore, the liquidus, solidus, and solvus temperatures are those in which their respective lines intersect the vertical dashed line at the composition of interest. The eutectic temperature is the same, regardless of the composition.