‘Stainless magnesium’ looks attainable after alloy is tested at Australian Synchrotron
After $221 million in the building and eight years operation, the Australian Synchrotron has helped local researchers come up with a material they say will boost the trucking industry.
The synchrotron accelerates electrons to nearly the speed of light to form an enormously powerful light beam and X-rays for extremely high-resolution imaging and structural analysis.
The researchers, led by a team at the University of New South Wales (UNSW), used it to turn the discovery of an ultra-low density and corrosion-resistant magnesium alloy that they believe will take a significant amount of weight off certain truck parts.
The facility’s operator, Synchrotron Light Source Australia (SLSA), says the discovery is the first step toward mass-producing, a new high-strength, lightweight metal for cars, trucks and aeroplanes, dubbed ‘stainless magnesium’.
The magnesium-lithium alloy weighs half as much as aluminium and is 30 per cent lighter than magnesium, making it an attractive candidate to replace these commonly used metals to improve fuel efficiency and greatly reduce greenhouse gas emissions from transport vehicles.
The findings, published in the current edition of Nature Materials with researchers from Monash University in Melbourne, describe how the alloy forms a protective layer of carbonate-rich film upon atmospheric exposure, making it immune to corrosion when tested in laboratory settings.
Professor Michael Ferry, from UNSW’s School of Materials Science and Engineering, says this formation of a protective surface layer can be considered similar to the way a layer of chromium oxide enables the protection of stainless steel.
“Many similar alloys have been created as researchers seek to combine the incredible lightness of lithium with the strength and durability of magnesium to develop a new metal that will boost the fuel efficiency and distance capacity of aeroplanes, cars and spacecraft,” Ferry says.
“This is the first magnesium-lithium alloy to stop corrosion from irreversibly eating into the alloy, as the balance of elements interacts with ambient air to form a surface layer which, even if scraped off repeatedly, rapidly reforms to create reliable and durable protection.”
Ferry, the senior author of the paper led by Dr Wanqiang Xu, also from UNSW, says this excellent corrosion resistance was observed by chance, when his team noticed a heat-treated sample from giant Chinese aluminium producer Chalco sitting inert in a beaker of water.
“To see no corroded surfaces was perplexing and, by partnering with scientists on the powder diffraction (PD) beamline at the Australian Synchrotron, we found the alloy contains a unique nanostructure that enables the formation of a protective surface film.
“Now we’ve turned our attention to investigating the molecular composition of the underlying alloy and the carbonate-rich surface film, to understand how the corrosion process is impeded in this ‘stainless magnesium’.”
Professor Nick Birbilis, of Monash University’s School of Materials Science and Engineering , says viewing unprecedented structural detail of the alloy through the Australian Synchrotron will enable the team, involving researchers from Monash University, Chalco, and Nanjing University of Technology in China, to work toward commercialising the new metal.
“Through our close collaborator, Dr Yang Xiao, we have strong ties to the Zhengzhou Light Metals Research Institute of Chalco in China,” Birbilis says
“We’re aiming to take the knowledge gleaned at the Australian Synchrotron to incorporate new techniques into the mass-production of this unique alloy in sheets of varying thickness, in a standard processing plant.
“These panels will make many vehicles and consumer products much lighter and, eventually, just as durable as today’s corrosion-resistant stainless steel, another example of how advanced manufacturing is unlocking the potential of materials that have been under investigation, in too narrow a manner, for centuries.”