The tantalum-10 tungsten (Ta-10W) alloy is also an extremely important refractory metal material. Its smelting process is centered around three core goals: overcoming high melting points, ensuring uniform composition, and achieving purification.
Mixing powder and forming: Rolling mixer, hydraulic press. Ta powder: W powder = 9:1; mixing speed 120 r/min, time 24 hours; pass through 120 mesh sieve; pressing pressure 500 tons. Obtain alloy powder with uniform macroscopic composition, and press it into alloy bars with certain strength and shape, which will be used as self-consuming electrodes for subsequent smelting. Vacuum sintering: Vacuum sintering furnace. Vacuum degree 10⁻² Pa; temperature 240℃, hold for 2 hours. This step is the crucial "pre-alloying" process. Perform low-temperature sintering on the pressed piece in a vacuum environment, making it have certain conductivity and mechanical strength, becoming a conductive coarse ingot, preparing for the next electron beam smelting. Vacuum electron beam smelting: Vacuum electron beam furnace (EBM). More than 2 smeltings; vacuum degree can reach 10⁻⁴ Pa; electron beam heating temperature can locally exceed 3000℃. This is the core part of purification and homogenization. High temperature and high vacuum enable efficient volatilization of gas impurities (O, N, H) and volatile metal impurities in the material. Multiple smeltings can greatly improve the chemical composition and uniformity of the ingot. Subsequent processing: high-frequency furnace, forging machine, rolling machine. Heat to 1400℃ for multiple forging; final rolling, drawing. Process the smelted ingot through plastic deformation at high temperature, break the cast structure, improve mechanical properties, and finally process into the required plates, bars, wires, etc.
In addition to the traditional melting-processing route, the preparation of Ta-10W alloy is also embracing new technologies. According to the latest research in 2024, the Laser Powder Bed Fusion (LPBF) technology has successfully been used to manufacture high-density Ta-10W alloy samples.
The superior LPBF technology can directly form components with complex geometries, breaking through the limitations of traditional manufacturing methods in the production of complex structures. Research has shown that under optimized process parameters (for example, with an energy density of 200 J/mm³), the Ta-10W alloy formed by LPBF can achieve a tensile strength of 765 MPa at room temperature and an elongation of 28%, demonstrating excellent comprehensive mechanical properties.
The challenge lies in the extremely high melting points of Ta and W, which results in a very narrow process window for LPBF. Precise control of parameters such as laser power and scanning speed is necessary to avoid defects like cracks and pores. In summary, the melting and preparation of Ta-10W alloy follows a "traditional and innovative coexistence" approach. The traditional "powder metallurgy + electron beam melting" process is mature and reliable, and is the industrial standard for producing large-sized and high-quality ingots. Meanwhile, the emerging LPBF additive manufacturing technology has opened up new possibilities for manufacturing complex and precise components and achieving high-value applications of materials.
