U.S. researchers say they've learned how make an aluminum alloy -- a mixture of aluminum and other elements -- that's as strong as steel.

North Carolina State University scientists say the search for ever lighter yet stronger materials is important for everything from more fuel-efficient cars to safer airplanes.

Yuntian Zhu, professor of materials science at NC State, says nanoscale architecture within the new aluminum alloys give them unprecedented strength but also reasonable plasticity to stretch and not break under stress, a university release reports.

The new aluminum alloys have unique structural elements called "grains," each a tiny crystal less than 100 nanometers in size, that make them super-strong and ductile, Zhu says.

Bigger is not better in materials, he says, as smaller grains result in stronger materials.

The technique of creating these nanostructures can be used on many different types of metals, Zhu says.

He says he is working on strengthening magnesium, a metal even lighter than aluminum, and is working with the Department of Defense to make magnesium alloys strong enough to be used as body armor for soldiers.