Tantalum is preferably of at least 99.995% purity and preferably of at least 99.999% purity. In addition, the invention relates to tantalum metal and its alloy having a particle size of approximately 50 microns or less; Or it has such texture that within any 5% thickness increment, the logarithmic ratio of (100) strength is less than about 15random or (111)∶(100) strength is greater than about -4.0; Or any combination of these properties. The invention also relates to articles and components made of tantalum metal, including but not limited to sputtering targets, capacitor shells, resistance film layers, wires, etc. The present invention also relates to a method for preparing a high purity tantalum metal including a step for the reaction of a tantalum-containing salt in a reaction vessel with at least one compound capable of reducing the salt to tantalum powder and a second salt. The reaction vessel, or the lining of the reaction vessel and the agitator, or the lining on the agitator, are made of metallic materials having a vapor pressure equal to or higher than that of molten tantalum. The high purity tantalum preferably has fine and uniform microstructure.
In processing tantalum, tantalum ore is first obtained, then it is broken, tantalum is separated from the broken ore with an acid solution, and then the solution containing tantalum is separated from the density of the acid solution containing niobium and impurities. The tantalum-containing acid solution is then crystallized into a salt and the tantalum-containing salt is reacted with pure sodium in a vessel having an agitator usually made of a nickel alloy material of which tungsten or molybdenum is a component. The vessel is usually double-walled and has an inner surface of pure nickel. The salt is then dissolved in water to obtain tantalum powder. In this process, however, tantalum powder is contaminated by surfaces in contact with it, such as surfaces containing tungsten and/or molybdenum. Many contaminants can evaporate during subsequent smelting, with the exception of highly soluble refractory metals such as Nb, Mo, and W. These impurities are extremely difficult or impossible to remove, thus impeding the availability of exceptionally high purity tantalum products.
Therefore, higher purity tantalum products are needed, which are largely free of contaminants from the above processes. At the same time, tantalum with higher purity, finer grain size and/or even texture is required. This fine particle size is an important property for tantalum targets because it improves the uniformity of the thickness of the sputtering deposited film. In addition, for other tantalum-containing products, fine particle size can improve deformation uniformity and enhance deep drawing ductility, which are beneficial for the manufacture of capacitor shells and laboratory crucible, and increase the lethality of explosive penetrants (EFP's). The uniform texture of tantalum products can improve the sputtering efficiency (such as greater sputtering rate) and anisotropy (improve deep resistance) of these tantalum products.
