Ta-W alloy is widely used in aerospace, national defense, chemical industry and nuclear industry due to its high density, high melting point, high elastic modulus, high ductility, good machining performance, high temperature strength, corrosion resistance, weldability and low plastic-brittle transition temperature. Tungsten can be added to tantalum to form solid solution alloy, which plays a role in solid solution strengthening and grain refinement. With the increase of tungsten content, the properties of tantalum-tungsten alloy at room temperature and high temperature are obviously improved.
With the development of vacuum, electronic and nuclear energy industries, high strength, thin, high tungsten content tantalum tungsten alloy foil has become the magnetron cathode, vacuum tube cathode, grid, high voltage rectifier components of the materials must be selected. Among them, one of the important uses of tantalum tungsten alloy foil with high tungsten content is to make primary cathode for magnetron. The strength and thickness of tantalum tungsten alloy box material directly affect the emission efficiency of cathode, output power of microwave tube and working stability under the same accelerating voltage.
Therefore, how to improve the strength of tantalum-tungsten alloy case material and process it into ultra-thin case material is the main task of current researchers and producers. For this task, a series of tantalum-tungsten alloy boxes have been developed, including tantalum-tungsten alloy foil with tungsten content of 2.5wt%, 5.0wt %, and 7.5wt %, whose thickness is less than 7mi. In addition, the tantalum-tungsten alloy foil used as the primary cathode of magnetron requires higher strength and better heat resistance and lodging resistance, which requires further improvement of the tungsten content in tantalum-tungsten alloy. The Ta-W binary alloy composed of tungsten and tungsten is an infinite solid solution, and the strength of the alloy increases with the increase of the tungsten content. Tantalum-tungsten alloys produced industrially in the United States are Ta-2.5W, Ta-7.5W and Ta-10W. These tantalum alloys maintain the low temperature plasticity of pure tantalum, and have high strength and oxidation resistance. Since the 1960s, tantalum-tungsten alloys have been used as high temperature structural materials and corrosion resistant materials in aerospace and chemical industries. In 1979, Ta-10W alloy developed in China was put into industrial production. However, over 12°% ~ 14% (atomic fraction), the plasticity of the recrystallized alloy decreases significantly, and the processing properties of the recrystallized alloy deteriorate significantly. It is very difficult to prepare the tantalum tungsten alloy foil. So far, no processing technology for tantalum tungsten alloy foil with tungsten content over 10.
