Tantalum-2.5tungsten alloy is a low-tungsten-content tantalum-based solid solution strengthened alloy wire. Through the solid solution strengthening of a small amount of tungsten, it significantly enhances the strength at room temperature/medium and high temperatures and creep resistance while retaining the excellent corrosion resistance, high plasticity and dielectric properties of pure tantalum. At the same time, it avoids the adverse effects of high tungsten content (such as Ta-10W) on processability. It is a key wire material that combines "precision processability" and "environmental adaptability" in fields such as electronics, medical care, and aerospace.
Compared with pure tantalum wire, the room-temperature strength of Ta-2.5W wire is increased by 30% to 50%, while still maintaining excellent plasticity. It can be cold-drawn to extremely fine specifications (minimum diameter 0.01mm, that is, 10μm), and has good bending, winding and welding properties, making it suitable for manufacturing precision electronic components and micro-structural parts. It has excellent medium and high-temperature stability, maintaining stable mechanical properties within the range of 800-1200℃. Its creep resistance is significantly better than that of pure tantalum wire. It can be used for a long time below 1000℃ (in an inert atmosphere/vacuum environment), and the short-term service temperature can reach 1500℃. Its corrosion resistance is comparable to that of pure tantalum, inheriting the core corrosion resistance characteristics of tantalum. Except for hydrofluoric acid, hot concentrated phosphoric acid, molten alkali and fluorine-containing compounds, it can resist the vast majority of organic/inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid and aqua regia (including concentrated acid environments below 200℃), and its corrosion resistance is superior to that of titanium wire and stainless steel wire. The dielectric performance is stable. The surface oxide film (Ta2O5) is dense and uniform, with a high dielectric constant (≈26) and a high breakdown field strength (≈5.8×106V/cm). Moreover, the capacitance value change rate is low in high-temperature and high-humidity environments, making it suitable for electrodes/leads of electronic devices. The antioxidant brittleness and biocompatibility low tungsten content design reduces the risk of high-temperature brittleness and is less likely to crack when exposed to air for a short period of time (< 500℃). Non-toxic and non-allergenic, with biocompatibility close to that of pure tantalum, it can be used in medical implants.
Raw material preparation: Electron beam melting (EBM) was used to prepare Ta-2.5W alloy ingots (with diameters ranging from Φ100 to 200mm), ensuring uniform solid solution of tungsten and eliminating segregation. Billet opening and wire drawing: Hot forging/hot extrusion at 1400-1500℃ to process the ingot into bars with a diameter of Φ10-20mm. After multiple cold drawing passes at room temperature, the diameter is gradually reduced. The deformation amount of each pass is controlled at 15%-25% to avoid excessive work hardening. Intermediate annealing is carried out at 1100℃ vacuum annealing every 3 to 5 wire drawing passes to eliminate internal stress and restore plasticity. Surface treatment pickling uses a mixed solution of hydrofluoric acid and nitric acid to remove surface oxide scale and impurities. Electrolytic polishing enhances surface finish (Ra≤0.2μm), ensuring the uniformity of dielectric properties in electronic device applications. Precision straightening and inspection: Ensure the straightness of the wire material (≤0.1mm/m) through precision straightening equipment, and inspect the diameter tolerance (±0.002mm, precision grade), tensile strength and surface defects of each roll.
It was developed to address the issue that pure tantalum wire may undergo creep relaxation or deformation due to insufficient strength under high temperatures or long-term loads. Its strength is sufficient to meet more demanding mechanical requirements, while the plastic loss is very small. The outstanding corrosion resistance fully inherits the top resistance of pure tantalum to strong acid media. The increase in the recrystallization temperature for higher high-temperature stability means that it can maintain the strength and microstructure after cold working for a longer time at high temperatures, and has a stronger anti-sagging ability. Its comprehensive processability is similar to that of pure tantalum wire. It can be drawn, bent, braided, wound and welded (with protective atmosphere required), and the processing difficulty is only slightly higher than that of pure tantalum.
When the strength of pure tantalum wire is insufficient and Ta-10W wire appears to be "over-performing" and too expensive, Ta-2.5W wire offers just the right boost. Without sacrificing the most valuable corrosion resistance and biocompatibility of tantalum, the dimensional stability and structural reliability of the material under high temperature or continuous stress have been significantly improved through mild alloying. Among numerous high-end applications that require the form of wire, it has become the preferred tantalum alloy wire for designers and engineers when dealing with medium-strength, high-corrosion, and high-temperature stability demands due to its excellent comprehensive performance, relatively better processability, and cost controllability.
