Niobium tungsten alloy is often prepared by powder metallurgy and melting method. Powder metallurgy method is to mix, press and sintering niobium, tungsten and other elements powder into pre-alloy strips, and then use more than two vacuum electron beam melting or vacuum arc melting or the combination of these two melting methods to prepare ingot. The purpose of electron beam melting is to remove impurities (such as gap elements, low melting point metals and non-metallic impurities) from the pre-alloy strip, control the alloy composition and prepare a certain size of ingot. The purpose of vacuum arc melting is to produce ingot with more uniform composition, finer grain and larger diameter. After the ingot cutting, the billet is extruded and forged at temperatures above 1200 ° C, and then rolled and drawn at temperatures below 500 ° C to prepare bars, plates, strips, wires and other products.
Niobium tungsten alloy is generally welded by inert gas shielded tungsten electrode welding and electron beam welding processes, and can also be brazed with titanium and titanium alloys. Before welding, the welding metal must be cleaned with CCl4 and other organic solvents, and the welding operation must be carried out in a high vacuum (vacuum less than 1.333 ×10Pa) or high purity inert gas protection chamber. The welding operation of niobium tungsten alloy must be very careful, otherwise it is not easy to get a good plastic joint.
Stress relief annealing, recrystallization annealing and high temperature solution aging treatment are often used.
When used in high temperature oxidation environment, anti-oxidation coating must be added. Cr-Ti-Si and Cr-Fe-Si coatings are often used to obtain better oxidation resistance.
