Platinum-Iridium Spooled Wire (Pt70-Ir30)

Platinum/Iridium Alloy Spooled Wire (Pt70/Ir30) is the highest-iridium and most mechanically demanding grade in the spooled platinum-iridium wire series, with 30% iridium delivering the maximum hardness (280–285 HV), highest tensile strength (980–1100 MPa), and highest elastic modulus (236 GPa) in the range. Its melting point of 2153 °C — considerably above that of Pt90/Ir10 at 1800 °C — reflects the dominant contribution of iridium to the alloy's thermal character, and the density of 21.7 g/cm³ gives it exceptional mass per unit length for applications where the wire itself must contribute mechanical or inertial stability. Electrical resistivity of 35 µΩ·cm and a low temperature coefficient are consistent with the iridium-enriched composition. Peer-reviewed first-principles studies confirm that strength and modulus increase monotonically with iridium content, driven by solid solution strengthening from the large modulus misfit between platinum and iridium lattice sites, while elongation at break (18% for this grade) reflects the reduced ductility that accompanies the strengthening effect. Its arc erosion resistance, wear resistance, and chemical inertness at elevated temperatures make it the natural choice wherever Pt-Ir wire must endure the most mechanically and thermally demanding service conditions. Typical applications include high-load precision electrical contacts, arc erosion-resistant ignition and discharge electrodes, neural stimulation and recording electrodes requiring maximum structural rigidity, and scientific instrumentation components where the dimensional stability and high modulus of the wire are primary design drivers. In research, it is used in surface science, high-precision electrode fabrication, and materials investigations of refractory precious metal alloy behaviour.