Platinum Iridium wire, 1.0mm (0.04in) dia, hard is used in non-standard thermocouples, electrical contacts and as electrodes in medical research.
Iridium is the addition to platinum most oftenused to provide improved mechanical properties.It increases resistance to corrosion whilethe alloy retains its workability. Up to 20%iridium, the alloys are quite ductile. Withhigher iridium content fabrication becomesdifficult.
Platinum–iridium alloys are employed forinstruments, magneto contacts, and jewelry.The alloys are hard, tough, and noncorrosive.An alloy of 95% platinum and 5% iridium,when hard-worked, has a Brinell hardness of170; an alloy with 30% iridium has a hardnessof 400. The 5 and 10% alloys are used forjewelry manufacture; the 25 and 30% alloys areemployed for making surgical instruments. An alloy of 80% platinum and 20% iridium is usedfor magneto contact points, and the 90–10 alloyis widely used for electric contacts in industrialcontrol devices. The addition of iridium doesnot alter the color of the platinum. The 5% alloydissolves readily in aqua regia; the 30% alloydissolves slowly.
