Methods for improving the hafnium content of tantalum tungsten alloy include: 1. Mixing tantalum powder, tungsten powder and hafnium powder according to the designed content to obtain mixed powder; 2. 2. Press the mixed powder into billet strips; Third, the billet is sintered at high temperature in vacuum to get sintered billet; The sintered billet was fused twice by vacuum electron beam to obtain tantalum-tungsten alloy. The invention adopts high temperature vacuum sintering the raw powder finish at the same time, in the process of the alloying in cooling process in a timely manner filled with argon gas protection, effectively reduce the evaporation of hafnium, and rapidly in the process of vacuum electron beam melting in the two different melting speed, avoid the hafnium element was pumped out, at the same time promote the homogenization of tantalum tungsten alloy, further to avoid the hafnium element of a large number of volatile, The mass content of hafnium in the final tantalum-tungsten alloy is more than 80% of the designed content.
Tantalum alloy has the advantages of high melting point, high strength, good plasticity at room temperature, corrosion resistance and easy machining. It is widely used in chemical industry, aviation, aerospace and atomic energy industry. At present, there are mainly Ta2.5W, Ta10W and Ta12W tantalum alloys used in our country. But all these alloys have the problem of non-oxidation resistance. By adding a certain amount of hafnium element, the oxygen solubility of the alloy can be effectively reduced, and the corrosion resistance of the alloy to potassium, sodium, lithium, cesium, mercury and other alkali metals can be improved. After adding hafnium element, the alloy has good high temperature performance and machining performance. In the temperature range from -160℃ to 1370℃, the alloy keeps good ductility and strength, and can work in extreme environments such as ultra-high temperature, ultra-high pressure, high-speed airflow erosion, rapid cooling and rapid heat.
As refractory metal alloys, TaW series alloys have a high melting point and are easy to oxidize. They are generally prepared by vacuum electron beam melting and a small amount by powder metallurgy. The melting point of hafnium is 2222℃, which is nearly 800℃ lower than that of Ta. Near the melting point of hafnium, the vapor pressure of hafnium is 3 orders of magnitude higher than that of tantalum. Therefore, hafnium melts first than tantalum in vacuum melting, and it is extremely volatile. The United States adopt the method of electron beam melting and electric arc furnace smelting, high melting point, difficult to volatilize with electron beam melting, alloying, tantalum, tungsten to add the hafnium in electric arc furnace smelting, combines two smelting ways, both achieve the purification effect of electron beam melting, use of the advantages of the fast smelting electric arc furnace, and also avoid the problem of Hf elements volatilize uncontrollable.
