The rare earth metal scandium is one of the most common rare earth metals on the planet; however, it is only found in very small concentrations, and it's very difficult to separate it out from the ore. When added to aluminium alloys, scandium can significantly improve their properties, especially in the case of alloys that cannot be hardened through heat treatment.
For example, adding scandium to aluminium magnesium alloys increases their yield strength 2–2.5 times, while preserving density and corrosion resistance. Adding scandium improves the quality of weld joints for alloys, avoiding cracks in welds, and increases the fatigue life of metal by up to 200%.
Scandium is also added to high strength aluminium lithium alloys and Al-Zn-Mg-Cu alloys as a modificator and anti-crystallisation agent for the purpose of grinding cast grains.
Because of their high cost, aluminium scandium alloys are used primarily in the aerospace industry, where they can be found in fuel tanks, the welded elements of instrumentation panels, instrumentation boxes, and large-scale stamped and welded elements.
In Russia, aluminium scandium alloys are used in the manufacture of such spacecraft as Fobos and Mars-96, as well as equipment manufactured by S. Lavochkin NPO, Academician Makeyev State Rocket Center (Makeyev SRC) and MKB Fakel.
Aluminium alloys with scandium are also used in the manufacture of high strength sports equipment, such as tennis rackets, golf clubs, baseball bats and bicycle frames. The US-based arms manufacturer Smith & Wesson produces revolvers with bodies made from aluminium scandium alloys.
Due to their high corrosion resistance and strength, aluminium-scandium alloys have got great prospects in the production of pipes for the oil and gas industry, the manufacture of construction elements for frames, bridges, masts and power line pylons, they can be used in ship building, in the automotive and rail industries, as well as in the manufacture of liquid hydrogen tanks that operate at cryogenic temperatures.
Aluminium Association member UC RUSAL has developed a process for making scandium oxide from red mud, a by-product of alumina production. Today, the Company's technicians are working to create a low cost aluminium alloy with a content of scandium of no more than 0.1%.
In view of access to raw materials, the introduction of modern alloy production technologies and the use of in-house alloying agents, the Company has managed to reduce the cost of producing scandium alloys by a factor of two. Once the project is completed, UC RUSAL plans to bring a new product onto the market: aluminium scandium alloy slabs and billets.
The Aluminium Association is negotiating with prospective consumers of aluminium scandium alloys.