Zirconium and hafnium properties

Zirconium was discovered in 1789 by Klaproth and first obtained in impure metallic form in 1824 by Berzelius. It wasn't until 1925 that this metal was produced in the laboratory in a very pure and therefore highly ductile form by Van Arkel and De Boer.

Hafnium was not isolated until 1923 by Coster and De Hevesy. The desire to build nuclear-powered submarines led to the selection of zirconium as the only structural element suitable for the construction of a compact reactor. This need, at a time when zirconium metallurgy did not exist, prompted major studies, first in the United States and then in France:

• obtaining ductile zirconium,

• zirconium-hafnium separation,

• development of melting furnaces,

• research into alloys resistant to aqueous corrosion,

• processing conditions,

• behavior under irradiation.

The metallurgy of these metals began its industrial development around 1950 in the USA, and around 1960 in France. In 2013, global capacity was around 7,000 tonnes of zirconium alloys, with the main producers being the USA, France, Russia and India, with China also entering the market. Hafnium capacities are very limited and dependent on those of zirconium, since the only sources of hafnium are zirconium ores, which contain only 2-4%.

Initially developed solely for nuclear applications, these metals have seen their field of application broadened, thanks to their excellent resistance to corrosion in a wide range of aggressive environments. They can be used in chemical applications (resistance to acids or bases), and for certain medical applications (prostheses).

This article presents the main physical properties, corrosion resistance, mechanical properties (significantly anisotropic), as well as the main alloys and their processing.