Niobium and tantalum are the fifth and sixth periodic elements of the VB family in the periodic table of elements. The element symbols are Nb and Ta, the atomic numbers are 41 and 73, and the relative atomic masses are 92.90638 and 180.9479, respectively. All of them are rare high melting point metals. Niobium and tantalum have very similar properties and are called similar elements.
Niobium is a glossy gray metal with paramagnetism. The ductility of high purity niobium metal is higher, but it will harden with the increase of impurity content. Niobium has a very low capture cross section for thermal neutrons, so it is of considerable use in the nuclear industry.
Niobium metal is stable at room temperature and begins to oxidize to form a dense oxide film at 200 C. It can resist the corrosion of molten alkali and various acids.
Tantalum is a silver-white metal with good corrosion resistance. It only reacts with fluorine, hydrofluoric acid, strong alkali solution and fuming sulfuric acid below 200 C. At room temperature, it is not affected by hydrochloric acid, nitric acid and sulfuric acid, and does not interact with aqua regia. It has great stability to acid.
Tantalum is ductile and can be drawn into thin wire foil. The coefficient of thermal expansion is very small. It expands only 0.00066% for every 1 C increase. In addition, its toughness is very strong, even better than copper.
Tantalum occupies an important position in surgical medicine. It can not only be used to manufacture medical devices, but also be a good "bio-adaptable material". For example, tantalum sheets can be used to repair skull damage, tantalum wires can be used to suture nerves and tendons, tantalum strips can replace broken bones and joints, tantalum yarn or tantalum mesh made of tantalum wires can be used to compensate for muscle tissue...
Both of them belong to high melting point metals, with stable chemical properties, compression resistance and wear resistance, and are excellent superconducting materials. Therefore, they are widely used in various fields and belong to important strategic resources.
