The invention relates to a method for increasing the hafnium content in tantalum-tungsten alloy, which includes: 1. The tantalum powder, tungsten powder and hafnium powder are mixed evenly according to the design content to obtain the mixed powder; 2. Press the mixed powder into billet; 3. Sintered blanks are obtained by vacuum sintering at high temperature; Four, the sintered billet is melted 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 quality content of hafnium in the final tantalum-tungsten alloy is more than 80% of the design content.
Tantalum alloy has many advantages, such as high melting point, high strength, good ductility at room temperature, corrosion resistance and easy processing. It is widely used in chemical, aviation, aerospace and atomic energy industries. At present, there are ta2.5W, Ta10W and Ta12W tantalum alloys in China, but they are not oxidation resistant. By adding a certain amount of Hf element, the solubility of oxygen in the alloy can be effectively reduced, and the corrosion resistance of alkali metals such as potassium, sodium, lithium, cesium and mercury can be improved. After Hf element is added, the alloy has good high-temperature performance and machining performance. The alloy maintains good ductility and strength in the temperature range from -160℃ to 1370℃, and can work in extreme conditions such as ultra-high temperature, ultra-high pressure, high-speed airflow erosion, quenching and heating.
The results show that the Ta10W alloy reflux coil is seriously corroded by potassium at 980℃, but the Ta8W2Hf alloy will not be corroded at 1315℃ for 2000h. The reason is that the O element in Ta10W dissolves in the tantalum matrix during the processing and testing process, and the high oxygen content in the grain boundary area leads to the preferential corrosion of the alkaline metal to the intergranular area and the formation of cavities. Hf is added to form a stable oxide, which is almost free from the erosion of alkaline metals, thus significantly improving the corrosion resistance of the alloy.
