By adding small quantities of elements such as lead to certain materials, scientists at the University of Wisconsin-Madison have discovered they can make a more versatile aluminum alloy that’s stronger by weight than steel.
The alloy’s strength originates from the effect of almost countless numbers of tiny pure-aluminum particles, called nanocrystals, dispersed uniformly throughout the material’s otherwise random, or amorphous, atomic structure. A miniature internal framework, the aluminum nanocrystals act as strengtheners by blocking the paths along which the amorphous alloy traditionally deforms.
The key is to produce and control the number and location of the nanocrystals, which have diameters about 10,000 times narrower than a human hair, says John Perepezko, materials science and engineering professor who conducted the research with then-graduate students Don Allen and James Foley. “What we found is that by adding tiny ‘seeds,’ such as lead particles, each particle acted as a little catalyst and produced an aluminum nanocrystal,” he says.
The strategy also can apply to other materials. For example, in iron-based alloys used for electronics applications, the lead nucleates nanocrystals that enhance not the material’s strength, but rather its magnetic properties.
The new materials, which manufacturers also can make in bulk form, could be used in everything from golf clubs and bicycles to transformers, airplane parts or other high-performance applications. Perepezko, whose research received funding from the Army Research Office, patented the discovery through the Wisconsin Alumni Research Foundation, a nonprofit organization that manages intellectual property in the interest of UW-Madison.