Researchers at the Cambridge-based Massachusetts Institute of Technology (MIT) say they've recently managed to create metals featuring a nanocrystalline structure. Their achievement could enable next-generation construction materials, and may have groundbreaking uses in other areas as well.
MIT scientists explain that metals ranging from steel to copper and gold feature a crystalline structure, meaning that they are made up of repeating patterns of ordered molecular arrays. While these materials are heavily used in construction, they do have some drawbacks.
One of the most important issues associated with their inner structure is the fact that the crystals can merge with each other and form larger objects, when the material itself is subjected to excessive amounts of heat or mechanical stress.
This is not a bad thing by itself, researchers add. However, in some applications, having access to a very fine, small-scale crystalline structure is desirable. What the MIT group did was create metals made up of nanocrystals, where each molecular array is just a few billionths of a meter across.
Early characterization studies of the new materials indicate that their nanocrystals do not experience mergers at rates seen in previous generations of metals, when subjected to high temperatures or stress.
Using the new metal alloys, it may become possible to design and build the next generation of high-strength structural materials, which would in turn allow for novel types of architectural forms to become possible.
In a paper published in the August 24 issue of the top journal Science, the MIT team says that it managed to develop a theoretical model that predicts the alloys which would form nanocrystals.
In addition, the research group also describes how it used the model to synthesize one of the predicted materials. The design/synthesis efforts were coordinated by MIT Department of Materials Science and Engineering (DMSE) graduate student Tongjai Chookajorn.
The team “derived a method to choose alloys that will remain stable at high temperatures. […] This research opens up the use of microstructurally stable nanocrystalline alloys in high temperature applications, such as engines for aircraft or power generation,” comments Julia Weertman.
The expert, who was not a part of the new investigation, holds an appointment as a professor emerita of materials science and engineering at the Northwestern University. The study was sponsored by the US Army Research Office.