Study shows nano-architectured aluminium has steely strength

A North Carolina State University researcher and colleagues have figured out a way to make an aluminium alloy, or a mixture of aluminium and other elements, just as strong as steel.

That's important, says Dr Yuntian Zhu, professor of materials science and the NC State researcher involved in the project, because the search for ever lighter - yet stronger - materials is crucial to devising everything from more fuel-efficient cars to safer airplanes.

In a paper published in the journal Nature Communications, Zhu and his colleagues describe the new nanoscale architecture within aluminium alloys that have unprecedented strength but also reasonable plasticity to stretch and not break under stress. Perhaps even more importantly, the technique of creating these nanostructures can be used on many different types of metals.

Zhu says the aluminium alloys have unique structural elements that, when combined to form a hierarchical structure at several nanoscale levels, make them super-strong and ductile.

The aluminium alloys have small building blocks, called 'grains,' that are thousands of times smaller than the width of a human hair. Each grain is a tiny crystal less than 100 nanometres in size. Bigger is not better in materials, Zhu says, as smaller grains result in stronger materials.

Zhu also says the aluminium alloys have a number of different types of crystal 'defects.' Nanocrystals with defects are stronger than perfect crystals.

Now, Zhu plans on working on strengthening magnesium, a metal that is even lighter than aluminium. He's collaborating with the Department of Defence on a project to make magnesium alloys strong enough to be used as body armour for soldiers.

Zhu's colleagues on the Nature Communications paper are affiliated with the University of Sydney in Australia; the University of California, Davis; and Ufa State Aviation Technical University in Russia.