Tantalum is a rare metal with high melting point, corrosion resistance, good plasticity and high chemical activity. Based on the above characteristics of tantalum, tantalum materials and tantalum products are often used in situations where good strength and stiffness are required at high temperatures, such as heaters, heat insulation parts, charging vessels, supporting parts and other high-temperature raw materials in the furnace. Various products produced with ordinary tantalum materials, such as crucible, heater, heat shield, etc., have a short service life. This is because tantalum is an active metal, and all the so-called gap elements such as oxygen, carbon, nitrogen and hydrogen will enter tantalum and become impurities under the action of a certain temperature and time. When ordinary tantalum is used for a long time above its recrystallization temperature, due to the limited purity of the ambient gas in the furnace, the escape of some gas elements after the heat absorption of the treated material, and the characteristics of tantalum material under heat inhalation, it can be used for a long time. The protective gas impurities in the furnace and the gas impurities escaping from the materials are adsorbed on the surface of the tantalum fittings in the furnace, and the oxygen and hydrogen adsorbed on the surface of the tantalum fittings in the furnace are converted into adsorbed oxygen and hydrogen atoms and dissolved in the tantalum crystal. Under the action of high temperature for a long time, the tantalum crystal carries accumulated oxygen and nitrogen atoms, which widens the tantalum lattice, expands the volume and hardens the grain. At the same time, the oxygen, nitrogen, oxides and nitrides in the grain boundaries move along the grain boundaries at a high temperature for a long time, making the grain boundaries empty, crystal expansion, grain embrittlement and loose, and finally causing the furnace tantalum accessories to be burned and embrittlement and scrap, which is a shortage of resources. Vacuum arc melting method is used to produce SGS tantalum ingots, and then the tantalum ingots are processed into tantalum products. The service life of tantalum crucible is 3000 furnace times /1650℃·2 hours, and the service life of tantalum sheet heater and tantalum heat shield is greater than 1500 furnace times /1650℃·2 hours. However, tantalum is a high melting point metal, and the production of SGS tantalum ingots by arc melting method has higher requirements for equipment and high production cost, which is not conducive to large-scale industrial production.
Add 110ppm of rare earth alloying element -- yttrium metal into the tantalum powder, mix and powder according to the process shown in Figure 1, and produce tantalum ingots with a diameter of 28mm by sintering forming method. The sintering temperature is controlled at 2000-2500℃ for 4-6 hours, and the yttrium-doped tantalum ingots are forged into 25mm forging blanks and annealed in vacuum at 1200℃. The annealing tantalum ingots were kept for 150 minutes, and the process rate was 6-8% of the thickness of the forging billet. When the thickness of the ingots was 2.5mm, the tantalum sheet was trimmed, and the end was welded into rolls with argon arc welding. During welding, the welding ends were cleaned with cleaning agent, which was prepared according to the weight ratio. The holding time is 150 minutes, the stress free tantalum coil is finished rolling, and the pass processing rate is 4 ~ 6% of the thickness.
