NaK

NaK, short for sodium–potassium alloy, is a eutectic alloy of sodium and potassium that is liquid at room temperature. The eutectic composition is about 22% sodium and 78% potassium by weight, and its melting point is approximately −12.6 °C. Because it remains liquid under ordinary conditions, NaK can offer high thermal conductivity and low viscosity as a heat-transfer fluid.

The alloy is highly reactive with water and with air. Contact with moisture or water produces hydrogen gas and heat, and exposure to air can lead to rapid oxidation and ignition, particularly for finer forms or heated material. Handling NaK requires precautions such as an inert atmosphere (dry nitrogen or argon) or immersion in mineral oil, and storage in containers that are compatible with alkali metals, typically under oil or in sealed, inert systems. In the event of spills, appropriate mitigation measures must be followed to prevent ignition and chemical burns.

Applications of NaK are mainly in specialized, high-temperature or research settings where a liquid alkali metal is advantageous. It has been used as a heat-transfer medium and coolant in certain niche laboratory and industrial systems and in some liquid-metal heat-pipe configurations. Its favorable thermal properties are balanced by significant safety and compatibility concerns, which limit widespread use.

Environmental and safety notes emphasize strict controls to avoid contact with moisture and air, proper protective equipment, and trained handling. Disposal and deactivation require professional procedures to prevent chemical hazards and environmental contamination.