SolidusTemperatur

SolidusTemperatur is a material property that denotes the highest temperature at which a material remains completely solid. In a multi-component alloy system, the solidus is the boundary below which solid phases exist; above the solidus, liquid forms appear and the material exists as a mixture of solid and liquid until the temperature reaches the liquidus, above which the material is fully liquid. For a pure substance, the solidus and the melting point coincide.

The solidus temperature depends on composition and phase history. In a phase diagram, the solidus is shown as a line separating solid-only regions from regions where solid and liquid coexist. The gap between the solidus and the liquidus for a given composition is called the solidification or mushy range. Alloying elements can raise or lower the solidus relative to the base metal’s melting point and may result in multiple solidus temperatures if more than one solid phase can exist.

Measurement and significance: Solidus temperatures are determined by techniques such as differential scanning calorimetry, differential thermal analysis, or hot-stage microscopy. In industrial processing, the solidus informs casting temperatures, welding procedures, and heat-treatment schedules. A narrow solidus–liquidus interval generally indicates simpler melting behavior and easier, more uniform solidification; a wide interval can promote segregation, porosity, or hot cracking during solidification.

Example: In pure metals, the solidus equals the melting point. In alloys, it varies with composition and can be substantially lower than the temperatures at which the alloy becomes fully liquid.