US scientists have used tiny defects in crystals to make stronger and more heat-resistant metal alloys that could be incorporated into future aircraft jet engines and power plants.
The research was led by Andreas Bezold, PhD, an assistant professor of materials science and engineering at the Ohio State University. He believes the approach could lead to more durable materials that withstand extreme heat.
Crystal defects are irregularities caused by imperfectly arranged atoms. But rather than a weakness, these defects could reportedly form complex three-dimensional (3D) structures. When carefully arranged, the imperfections could strengthen metals without altering their chemical composition.
“Defects are very important to learn more about, because by understanding how they interact with a material’s internal structure helps us design stronger materials,” Bezold pointed out.
When flaws become useful
All crystals contain tiny defects that disrupt their atomic structure and can change their properties. Although crystal defects are usually associated with damage or weakness, but arranging them correctly can actually make metals stronger.
To prove this, the research team worked with two materials: a cobalt-nickel-based superalloy and a cobalt-chromium-tungsten alloy. They first deformed the metal crystals and then aged them through heat treatment. This formed dense networks of atomically thin structures inside the alloys.
To the team’s surprise, the structures altered the arrangement of the atoms within the metals. And even made them better at withstanding stress and handling extreme heat. “We wanted to make these strengthening structures a deliberate part of the material’s design,” Bezold stated. “So it was fascinating to see how defects could have such a positive effect on the overall durability of the alloys.”
To better understand these changes, the team combined transmission electron microscopy with computer simulations. The results showed that the way atoms surround defects could determine how strong a metal becomes.
Jets and power plants
According to Michael Mills, PhD, a professor of materials science and engineering at the university and co-author of the study, the discovery could be particularly useful for technologies that operate under extreme heat and stress. These can include aircraft turbine engines or power plant machinery
Jet engines need metals that resist deformation at temperatures often exceeding 1,832 degrees Fahrenheit (1,000 degrees Celsius), while power plant components must withstand prolonged exposure to extreme heat.
“Seeing the strengthening process on the atomic scale was quite stunning, since despite being associated with damage, the right defects with the right structure and chemistry can actually make a material stronger,” Mills said in a press release.
The effort builds on earlier Ohio State research into defects that strengthen metals. It involved researchers from Ohio State, the University of Erlangen-Nuremberg, and Lawrence Livermore National Laboratory, with support from the NSF, DOE, and other organizations. The team hopes the findings will lead to better ways of designing stronger, high-performance materials.
“This is a field that is quickly becoming very exciting,” Bezold said. “We hope that this idea becomes a new lever that strengthens and pushes the limits of material engineering even further.”
The study has been published in the journal Science.