Aluminium Scandium Magnesium Alloys for Aerospace Applications

Scandium is a rare earth metal that, when added to aluminium alloys, boosts strength, heat and corrosion resistance and welding properties. Small additions of the material are found in sporting equipment such as baseball bats and bike frames, in firearms made by Smith & Wesson, and in some military aircraft. In the form of powder, scandium can also be used in 3D printing.

But global yearly demand for the metal is only around 10-15 tonnes, with most of that coming from aerospace. Airbus has developed a high-performance aluminium scandium magnesium powder metal, called Scalmalloy, which can be additive manufactured for use in aerospace structures. It is said to reduce the weight of a Boeing 737-sized airliner by 10%-15%.

The Crater Lake deposit is believed to hold the world’s highest concentration of scandium and the largest undeveloped supply source in North America. It is estimated to contain over a million tonnes of scandium oxide (2% by volume), which would be processed into metal through co-electrolysis and aqueous leaching.

UC Rusal has been researching the application of the rare-earth metal for several years, using technology developed by its specialised specialists in the extraction of aluminium from red mud – a waste byproduct from alumina production – in Russia and China. The company has been able to significantly increase the concentration of scandium in its master alloys, while reducing their cost to make them competitive with other high-performance aluminium alloys.

The mining and metals group has signed an agreement with Amaero, a leading specialist in metal additive manufacturing, to supply the first commercial batch of its specialized aluminium-scandium alloy. Amaero will process the alloy into a powder for use in metal 3D printing, and deploy it in high-temperature applications such as aerospace. Rio Tinto will deliver alloy billets combining high purity scandium oxide with responsibly produced, low-carbon aluminium from its hydro-powered smelters in Canada to create the new alloy.