Researchers at Purdue University (West Lafayette, Indiana, USA) have developed high-strength Al alloy coatings for potential use in aerospace and automobile industries.
“We have created a very durable and lightweight aluminum alloy that is just as strong as, and possibly stronger than, stainless steel,” says Xinghang Zhang, a materials engineering professor at Purdue who led the research team. “Our aluminum alloy provides flexibility that stainless steel does not in many applications.”
Yifan Zhang, a graduate student in materials engineering and another member of the research team, says the alloy could be used for making wear- and corrosion-resistant automobile parts such as engines, as well as coatings for optical lenses on specialized telescopes.
The researchers say they created the Al alloy by introducing “stacking faults,” or distortions in the crystal structure. Such distortions can lead to nanotwins and complex stacking faults. Nanotwins are small linear boundaries in a metal’s atomic lattice that have identical crystalline structures on both sides, allowing them to be more resistant to fatigue.
“The 9R type of stacking fault is usually rare in aluminum,” says Qiang Li, a doctoral student and research team member. “We introduce both twin boundaries and 9R phase within nanograins to the lightweight Al alloys that are both strong and highly deformable under stresses. Besides coating applications, we are also looking into scale-up potentials of bulk high-strength Al alloys.”
The team says they also created a way to develop the Al alloy coatings by introducing Fe or Ti atoms into the crystal structure. The resulting nanotwinned coatings were comparable in strength to high-strength steels, the researchers explain.
Source: Purdue University, www.purdue.edu.