Mechanical and thermoelectric properties of iridium-ruthenium alloy grown by the micro-pulling-down method

Abstract

Iridium, ruthenium, and iridium-ruthenium alloy wires were fabricated by the dewetting micro-pulling-down method, a type of unidirectional solidification method. The length of the grown Ir-20Ru reached 47 m. Furthermore, their mechanical and thermoelectric properties were investigated. The as-grown Ir-17.9Ru wire exhibited a tensile strength of approximately 765 MPa and a nominal fracture elongation of 21% at room temperature. After work-hardening by three cycles of winding and rewinding for a bending radius of 10 mm and annealing at 2273 K for 3 h, the tensile strength and fracture elongation of the Ir-Ru wire were 1061 MPa and 25%, respectively. From the electromotive force (EMF) characteristics of platinum obtained by integrating the Seebeck coefficient, the EMF characteristics from room temperature to ~ 2000 K of iridium, ruthenium, and Ir-17.9Ru were investigated. The EMF characteristics for several thermocouples using iridium, ruthenium, or Ir-17.9Ru as one of the pairs were estimated from the combination of the obtained EMF characteristics. Ir/Ir-17.9Ru showed similar EMF characteristics to Ir-40Rh/Ir.