Tungsten is an effective strengthening element of niobium, but with the increase of tungsten content, the ductile-brittle transition temperature of the alloy will increase and the grain size will grow significantly. Therefore, in order to obtain high strength niobium-tungsten alloys, the amount of tungsten added should be controlled properly, and the elements such as zirconium and hafnium that refine the grain and reduce the ductility to brittleness transition temperature should also be added appropriately.
Niobium-tungsten alloy can be divided into solid solution strengthening alloy and solid solution strengthening and diffusion strengthening alloy. Niobium-tungsten alloy has high strength at high temperature and good plasticity at room temperature. Various machining materials and parts can be made by conventional forming technology. It is mainly used in space shuttle skin, nuclear reactor engineering, jet engine parts and space power system thermal radiation screen and conduit.
The preparation method of tungsten alloy includes the following steps: 1) Pour 101 parts niobium, 15 parts tungsten carbide powder, 6 parts zirconium, 2 parts tin, 2 parts iridium, 6 parts hafnium carbide, 2 parts titanium carbide, 3 parts tantalum carbide and 3 parts ytterbium oxide into a metal melting furnace, and then heat to 900°C. After all the raw materials are completely melted, the liquid metal is prepared and used for later use. 2) Pour 2 parts of sintered aluminum, 2 parts of aluminum nitride, 2 parts of magnesium nitride, 2 parts of silicon dioxide, 2 parts of yttrium oxide and 3 parts of boron carbide into the nanometer pulverizer for grinding processing, and prepare nanometer powder for use; 3) Pour the nano-powder prepared in step 2) into the liquid mixed metal prepared in step 1), stir thoroughly, and prepare the mixed liquid metal for use; 4) Pour the mixed liquid metal prepared in step 3) into the die casting machine for die casting to obtain niobium-tungsten alloy.
The beneficial effect is: by adding iridium, hafnium carbide, tantalum carbide and other materials containing rare earth elements to modify niobium, making the phase structure and microstructure of niobium have a great change, and adding sintered aluminum and boron carbide to further strengthen, making the finished product with excellent strength.
