A gallium, indium, and tin alloy sold under the trade name Galinstan melts at −19 °C (−2 °F) and is liquid at ambient temperature. The term “galinstan” is also used in scientific literature to refer to the eutectic alloy of tin, gallium, and indium, which melts at about +11 °C (52 °F). Galinstan, a commercial product, is a near-eutectic alloy rather than a eutectic alloy. It also probably contains additional flux to lower surface tension, enhance flowability, and lower melting temperature.
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By weight, 68.5% Ga, 21.5% In, and 10.0% Sn make up eutectic galinstan.
In many applications, galinstan has taken the role of hazardous liquid mercury or the reactive alloy NaK because of the low toxicity and low reactivity of its component metals.
Uses
At mild temperatures, galinstan can be used in thermometers in place of mercury.
Compared to mercury, galinstan has a lower density and a higher reflectance. It can take the place of mercury in liquid-mirror telescopes used in astronomy.
Because of their superior thermal conductivity over thermal pastes and thermal epoxies, metals or alloys like galinstan that are liquid at room temperature are frequently used by overclockers and enthusiasts as a thermal interface for computer hardware cooling. This allows for the achievement of slightly higher clock speeds and CPU processing power during demonstrations and competitive overclocking. Thermal Grizzly Conductonaut and Coolaboratory Liquid Ultra are two instances, possessing respective thermal conductivities of 73 and 38.4 W/mK. Galinstan is electrically conductive and induces liquid metal embrittlement in various metals, including aluminum, which is frequently used in heatsinks. This is in contrast to regular thermal compounds, which are simple to apply and have a little chance of breaking expensive hardware. The users that are successful with their application claim positive outcomes in spite of these difficulties. For use in the PlayStation 5, Sony Interactive Entertainment patented a mass-producible galinstan-based thermal interface technology in August 2020.
The reason galinstan is challenging to employ in cooling fission-based nuclear reactors is that indium absorbs heat neutrons effectively and has a high absorption cross section, which prevents the fission process. On the other hand, research is being done on it as a potential coolant for fusion reactors. It is less dangerous than other liquid metals like mercury and lithium because of its nonreactivity.
Galanstan’s wetting properties may be employed to create conductive patterns, which makes it suitable for use as a liquid, pliable conductor in stretchy electronics and soft robots. Galinstan can be used to replace the conductive element in inductor coils, dielectric composites for soft capacitors, cables, interconnects, and electrodes.
X-ray apparatus
An X-ray source that uses a liquid-metal galinstan anode of 9.25 keV X-rays (gallium K-alpha line) can produce extremely high-intensity sources for X-ray phase microscopy of fixed tissue (like the brain of a mouse) from a focal spot of about 10 μm × 10 μm and 3-D voxels of about one cubic micrometer. Rapidly flowing metal is directed downward through a nozzle, and it is exposed to a high-intensity electron source. Due to forced-convective heat removal, the fast metal flow transfers current, but the physical flow limits anode heating significantly, and the high boiling point of galinstan prevents anode vaporization.