High-toughness/resistivity ruthenium-based refractory alloy wires

High-resistivity Ru–Mo–W-alloy wires, exhibiting excellent strength and ductility, were fabricated using the micro-pulling-down melt-growth method under vacuum for application as resistance heating wires. Furthermore, their mechanical and electrical properties were investigated. The fabricated Ru _0.6Mo _0.15W _0.25 wires (⌀0.8 mm × 10.8 m long) showed a room-temperature tensile strength and nominal rupture strain of 1287 MPa and 21.2%, respectively. Transmission electron microscopy of Ru _0.6Mo _0.15W _0.25 revealed the presence of active 11 2 ¯ 2 < 11 2 ¯ 3 > pyramidal slip systems. Ru _0.6Mo _0.15W _0.25 demonstrated an electrical resistivity of ∼0.936 μΩ∙m at 1873 K, 1.77 and 1.24 times higher than those of W and Ta, respectively. The dependence of the hemispherical total emissivity on temperature was also measured. The temperature dependence of the electrical resistivity of Ru _0.6Mo _0.15W _0.25 was lower than those of Ta and W. Furthermore, the hemispherical total emissivities of Ru _0.6Mo _0.15W _0.25 and Ta were comparable at ∼1800 K. When tested at 1873 K for approximately 3000 h, the durability of a Ru _0.6Mo _0.2W _0.2 wire was equal or superior to that of a Ta wire. The current (power) consumption required to deposit LiF and tris(8-hydroxyquinolinato)aluminum(III) (Alq ₃) at the same deposition rate using Ru _0.6Mo _0.2W _0.2 was 21% (11%) and 34% (12%) lower, respectively, than that when using conventional Ta heating wires. The results reveal that the Ru _0.6Mo _0.15W _0.25 heat-stabilization time was reduced by approximately 44%. Moreover, its deposition rate recovered more rapidly from errors such as a sudden boiling during heating.