Stainless magnesium ‘lighter than aluminium’

Metal molecules

Australian researchers have discovered an ultra-low density and corrosion-resistant magnesium-lithium allow that could greatly reduce the weight of cars and planes.

This has been described as the first step towards mass production of stainless magnesium, with the potential to change the automotive industry and aftersales services.

This latest discovery in corrosion-resistant magnesium allow research involved an element of luck, as a team of collaborating researchers from the University of New South Wales (UNSW) spotted a heat-treated magnesium alloy sitting inert in a beaker of water.

They found a unique nanostructure creating a protective layer of carbonate-rich film upon atmospheric exposure. They liken this to the way a protective film of chromium oxide forms on stainless steel, and report that it made the magnesium alloy immune to corrosion in the lab setting.

‘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,’ explained professor Michael Ferry, who led the UNSW team.

The magnesium-lithium alloy weighs half as much as aluminium and is 30 percent lighter than magnesium. This could see it find its way into lighter cars, trucks and aeroplanes that use significantly less fuel, which would put a huge dent in the transport sector’s carbon emissions.

It would also have an inevitable knock-on effect for collision repair, as the panels would be as durable though require a new set of working skills.

The team is now studying the molecular composition of the alloy and carbonate-rich film to better understand how the corrosion process is averted.

The research was published in the journal Nature Materials.

Source: Australian Synchrotron