#materials posts

Alloys: Constantan

Constantan is an alloy that is usually—but not necessarily—around 55% copper and 45% nickel. It was discovered in the late 1800s in Germany by Edward Weston and has remained popular because of its electrical resistance, namely that the resistivity remains constant over a wide range of temperatures. Because of this, constantan is often used in thermocouples, as well as in precision electrical instruments, such as resistors and strain gauges.

Alloys: Galinstan

The eutetic alloy of gallium, indium, and tin is often known as Galinstan, though the term is also technically a brand name. The alloy name is derived from the names of its three component elements, using the Latin for tin (stannum). Composition can vary in commercial Galinstan, but the eutetic of the alloy is 68.5% Ga, 21.5% In, and 10.0% Sn.

Galinstan is primarily used in liquid metal applications and has a melting temperature of around −19 °C (−2 °F), making it a liquid at room temperature. One application is the replacement of liquid mercury, as a non-toxic alternative in thermometers. It can also be used as a thermal interface material, or in electrical circuits.