Tantalum alloy based on the addition of a certain amount of tungsten element. Ta-W binary alloy composed of tantalum and tungsten is an infinite solid solution. The strength of the alloy increases with the increase of tungsten content, but the plasticity of the recrystallized alloy decreases significantly above 12% ~ 14%(atomic fraction) (see figure). Ta-2.5W, Ta-7.5W and Ta-10W are industrial tantalum - tungsten alloys produced in the United States. These tantalum alloys retain the low temperature plasticity of pure tantalum and have high strength and oxidation resistance. Since the 1960s, tantalum tungsten alloy has been used in aerospace and chemical industries as high temperature structural materials and corrosion resistant materials. In 1979, Ta-10W alloy developed by China was put into industrial production. The preparation method mainly adopts more than two times of vacuum electron beam smelting or vacuum arc smelting to prepare the billet, and then adopts forging or extruding to open the billet at the temperature above 1200℃, and then rolling and drawing at the temperature below 500℃. It can be made into plate, bar, wire, pipe and other products.
At present, in some strong acid medium heating heater used in the relatively backward technology, a lot also use made of cast iron pot heater, the heater with lower thermal conductivity of cast iron, and wall thickness thicker, caused a great waste of energy, when heated and acid corrosion of cast iron is more serious, cause the service life of the equipment is shorter, often only a few months, the serious influence the continuity of the heater is in process system, and even some heaters in heating process, cause a lot of acid mist emissions into the air, causing serious pollution to the environment.
Cutting, welding, heat treatment and coating are the same as tantalum alloy. Because the strength of tantalum tungsten alloy is higher than that of pure tantalum and its corrosion resistance is similar to that of pure tantalum, it has been used in chemical industry and aerospace industry. Ta-2.5W alloys are mainly used in the manufacture of heaters, cooling coils, heat exchangers and reactors. Ta-7.5W alloy is mainly used as spring material and other corrosion resistant elastic elements in chemical corrosion equipment. Tantalum and tantalum alloys have high potentials and become cathodes in contact with other metals, easily absorbing atomic hydrogen and making tantalum and tantalum alloys brittle. Therefore, when used in the manufacture of chemical equipment, it must be prevented from becoming a cathode. Ta-10W alloy can be used as liquid rocket engine thrust combustor with gas temperature above 3300℃, high-temperature vacuum furnace heating element and other high-temperature components.
