platinum-iridium alloy

platinum-iridium alloy

[′plat·ən·əm ə′rid·ē·əm ′al‚ȯi]
(metallurgy)
An alloy with 1-30% iridium; as concentration of iridium increases, so do hardness, chemical resistance, and melting point; used in jewelry, electrical contacts, and hypodermic needles.
References in periodicals archive ?
Forged against a backdrop of scientific and political upheaval following the French Revolution, a single, small cylinder of platinum-iridium alloy has laid largely undisturbed for nearly 130 years as the world's benchmark for what, precisely, is a kilogram.
This reference mass is used to calibrate national standards made of platinum-iridium alloy [2].
Experts are willing to make the changes so that it is no longer based on the mass of a solid cylinder of platinum-iridium alloy that sits beneath three layers of protective glass sealed in a locked vault in Sevres, France.his metal block, known as the International Prototype Kilogram, has been used since it was first registered with the International Bureau of Weights and Measures (BIPM) in 1889 as the definitive unit of mass against which all other kilograms are measured.
The International Prototype Kilogram (IPK) or "Le Grand K," made in the 1880s, is a bar of platinum-iridium alloy kept in a vault near Paris.
Among global standards for length, mass, time, and other fundamental quantities, only the kilogram remains a physical object--a carefully machined cylinder of platinum-iridium alloy at the International Bureau of Weights and Measures at Sevres, France.
Careful recalibration against the so-called international prototype of the kilogram -- a lump of platinum-iridium alloy that sits in a vault at the International Bureau of Weights and Measures in Sevres, France -- showed the U.S.