History of Rhenium and Alloys

  Rhenium was an unknown element when the periodic table was introduced in 1870. The properties predicted for an element of atomic #75 turned out to be in general agreement of those of rhenium when it was discovered in 1925. W. Noddack and O. Berg were the first to locate it in platinum ores such as columbite and tungstate. J.G.F. Druce discovered it independently in manganese sulphate. The ores from which rhenium was first extracted commercially came from the region of the river Rhine (Latin: Rhenus) hence the name rhenium was born.

  Rhenium’s melting point of 3180º C is second only to tungsten. Only osmium, iridium, and platinum exceed its density of 21.04 g/cc. Because of its high melting point, rhenium is a refractory metal. In that classification, rhenium is unique. It is the only refractory metal that does not form carbides. Its crystal structure is hexagonal close-packed (hcp), while other refractory metals have a body centered cubic (bcc) structure. Rhenium also does not have a ductile-to-brittle transition temperature it maintains its ductility from absolute zero all the way to its melting point and also has a high modulus of elasticity. This means that structures made of rhenium will have very good stability and rigidity.

  A high re-crystallization temperature is a pre-requisite for good creep resistance and among refractory metals, rhenium is the highest. At temperatures up to 2800º C and high stresses, the rupture life of rhenium is longer than tungsten. The metal also accommodates wide swings in temperature – large thermal expansions and contractions – without incurring mechanical damage.