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Why can sodium-potassium alloy serve as a heat-transfer coolant?
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![A periodic table element box for potassium shows atomic number 19, symbol K, atomic weight 39.0983, electron configuration [Ar]4s1, and name potassium. Icons indicate it is an alkali metal, solid at room temperature, body-centered cubic crystal structure, and has strongly basic higher-valence oxides. A key explains the symbols for alkali metals, solid state, body-centered cubic structure, and strong basicity.](https://cdn.britannica.com/81/22381-050-E3372C94/properties-Potassium.jpg)
potassium
Properties of potassium.
Sodium-potassium alloy, commercially known as NaK, serves as an effective heat-transfer coolant primarily because it is a highly efficient conductor of thermal energy.1
A key advantage of this alloy is its low melting point. While pure sodium and potassium are solid at room temperature, they form a eutectic mixture—an alloy that melts at a lower temperature than its individual components. Specifically, the NaK eutectic, which consists of approximately 78 percent potassium, melts at −10 °C (14 °F). This property allows the alloy to remain in a liquid state across a wide temperature range, making it highly suitable for transporting thermal energy away from the core in nuclear reactors and other industrial systems.213