Most of the applications of iridium utilize its high melting point, high hardness and anti-corrosion properties. Iridium metal and iridium-platinum alloys and osmium-iridium alloys have very low losses and can be used to make porous spinnerets. Spinnerets are used to extrude plastic polymers into fibers such as rayon. Osmium-iridium alloys are also used in compass bearings and weighing scales.

Iridium has strong corrosion resistance and high temperature resistance, so it is very suitable as an alloy additive. Some long-term components in aircraft engines are composed of iridium alloys, and iridium-titanium alloys are also used as underwater piping materials. The addition of iridium increases the hardness of platinum alloys. The Vickers hardness of pure platinum is 56HV, while the hardness of platinum alloy containing 50% iridium can exceed 500HV.
Iridium is also often used in instruments that must withstand high temperatures. For example, the Tchaikrasky method uses a high-temperature crucible made of iridium to produce individual crystals of oxides such as sapphire, gadolinium-gallium garnet, and yttrium-aluminum garnet. These crystals are used in computer memory and solid-state laser components. Iridium alloys are resistant to arc erosion, making them an ideal material for the electrical contacts of spark plugs.