High-toughness/resistivity ruthenium-based refractory alloy wires

Abstract

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 Ru0.6Mo0.15W0.25 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 Ru0.6Mo0.15W0.25 revealed the presence of active 112¯2<112¯3> pyramidal slip systems. Ru0.6Mo0.15W0.25 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 Ru0.6Mo0.15W0.25 was lower than those of Ta and W. Furthermore, the hemispherical total emissivities of Ru0.6Mo0.15W0.25 and Ta were comparable at ∼1800 K. When tested at 1873 K for approximately 3000 h, the durability of a Ru0.6Mo0.2W0.2 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) (Alq3) at the same deposition rate using Ru0.6Mo0.2W0.2 was 21% (11%) and 34% (12%) lower, respectively, than that when using conventional Ta heating wires. The results reveal that the Ru0.6Mo0.15W0.25 heat-stabilization time was reduced by approximately 44%. Moreover, its deposition rate recovered more rapidly from errors such as a sudden boiling during heating.