Tantalum alloy based on tantalum adds other elements to the alloy. Tantalum anode oxide film is very stable, corrosion resistant, dielectric properties excellent, suitable for making electrolytic capacitor. Tantalum is highly resistant to chemical corrosion. Except for hydrogen fluoride, sulfur trioxide, hydrofluoric acid, hot concentrated sulfuric acid and alkali, tantalum can resist the corrosion of all organic and inorganic acids. Therefore, it can be used as corrosion resistant materials for chemical industry and medicine. Tantalum carbide is an important additive in the manufacture of cemented carbide. Tantalum is also used in some tubes. In 1958, ta-10w alloy was put into production.
In the 1960s, tantalum alloy was used in the space industry as a high-temperature structural material. Tantalum and tantalum alloy products are sheet, strip, foil, bar, wire, and sintered products. China began to study tantalum smelting and plastic processing in the late 1950s, and tantalum and its alloy products were produced in the mid-1960s.
Alloy strengthening in refractory metal tantalum low-temperature plastic is the best, its plasticity - brittle transition temperature below 196 ℃. The excellent low temperature plasticity of tantalum must be considered in the development of tantalum alloy. Tantalum alloys often adopt the method of solid solution strengthening, and also use the method of solid solution and precipitation strengthening to improve the strength. Some adjacent elements in the periodic table of tantalum can be completely solid solution in tantalum, and some have high solubility. The most effective replacement elements are rhenium, tungsten, zirconium and hafnium.
If the amount of elements is added beyond a certain range, it will damage the low temperature plasticity of tantalum (see figure). It is generally believed that the percentage of atoms added should be less than 12 to 14%. The effect of interstitial elements nitrogen, carbon and oxygen on the strength of tantalum is not great, but the low temperature plasticity and processing plasticity of tantalum are obviously damaged. When these interstitial elements form dispersive precipitation with the active element zirconium or hafnium, the effect of enhancement is obvious.
Tantalum billet and its alloy blank can be produced by powder metallurgy or smelting process. Powder metallurgy is mainly used to produce small tantalum products and blank for processing. The powder tantalum prepared by thermal reduction or electrolysis is sintered in vacuum after being pressed into shape. The sintering process depends on the requirements of the product. A sintering (1600 ~ 2200 ℃) used in the production of smelting with electrodes and the porous anode. Secondary sintering is used to produce billets for forging, rolling and drawing. Forging or rolling is often carried out between sintering and sintering, and the machining rate is about 50%. Secondary sintering temperature is 2000 ~ 2700 ℃.
