Nb-5W-2Mo-1Zr (containing trace amounts of C: ~0.01%); Typical range: W 4.5–5.1 wt%, Mo 1.60–2.10 wt%, Zr 0.75–0.98 wt%, the remaining is niobium, and impurities (O, N, Fe, etc.) are strictly controlled at extremely low levels. The strengthening mechanism is solid solution strengthening + NbC/ZrC dispersion precipitation strengthening.
Density is approximately 8.7–8.8 g/cm³; melting point is approximately 2630°C; with coating protection, the long-term working temperature can reach 1550°C, significantly higher than that of traditional C103 niobium alloy (1200–1300°C); the room temperature elastic modulus is approximately 124 GPa (rod). Mechanical properties (forged rod in annealed state): tensile strength σb ≈ 440 MPa, yield strength σ0.2 ≈ 328 MPa, elongation δ5 ≈ 31%, reduction of area ψ ≈ 77%. The strength above 1400°C is almost twice that of C103, and the creep rate at 1300°C and 50 MPa is only about 1/100 of that of C103. Machining and oxidation resistance: can be hot forged, cold spun forged, and machined; requires siliconized molybdenum coating protection; the bare material is prone to rapid oxidation in high-temperature air; good welding performance, suitable for manufacturing complex hot-end components.
The mother ingot is prepared by vacuum electron beam melting (EB) or EB + vacuum self-consuming arc melting (VAR). The ingot is initially hot extruded at high temperature, then undergoes multiple passes of forging at 1300–1400°C (the most uniform microstructure is obtained after forging at 1400°C). Recrystallization is completed at 1350°C through vacuum annealing. Finally, it undergoes flaw detection (ultrasonic), finishing, and size inspection. It has good high-temperature strength and can be used above 1200°C (in vacuum or inert atmosphere). It has good corrosion resistance for liquid metals (such as sodium and potassium alloys) and certain molten salts. It has a low neutron absorption cross-section and is suitable for the nuclear industry. Processing-grade niobium alloys can generally be processed through methods such as forging, rolling, and drawing. Common diameters range from several tens of millimeters to over a hundred millimeters (such as φ70, φ160mm), and the length is customized according to customer requirements; the surface can be classified as black skin forged state, polished by turning, or polished core. Applications: liquid rocket engine nozzles, combustion chambers, extension sections; satellite attitude control engine thrust chambers; also used in nuclear industry high-temperature fixtures, high-temperature furnace components;
It is necessary to apply a coating to protect the bare material from rapid oxidation and failure in an air environment above 600°C. A Si-Mo and other high-temperature anti-oxidation coatings must be provided as a supplement.
Processing temperature control: The hot processing temperature should be 1300-1400°C. Avoiding low-temperature processing to prevent cracks. Atmosphere protection heat treatment and welding should be carried out in a vacuum or inert atmosphere such as argon to prevent embrittlement caused by hydrogen or oxygen absorption. Design adaptation: By taking advantage of its excellent high-temperature strength and creep resistance, the cooling system design can be reduced and the structural weight can be lowered.
The plasticity of this material can be processed by hot forging, cold spinning forging, extrusion, and rolling, and it is suitable for manufacturing rods, plates, tubes, etc. The welding performance is excellent, with the weld strength reaching over 90% of the base material, making it suitable for the assembly of complex components. The machinability is that it can be turned, milled, and drilled at room temperature, but hard alloy tools are required. Pay attention to heat dissipation to avoid processing hardening. The heat treatment characteristics recommend vacuum annealing at 1350°C to complete recrystallization and obtain uniform structure and the best comprehensive performance.
