Nav: Home

Finding order and structure in the atomic chaos where materials meet

April 20, 2017

Materials science researchers have developed a model that can account for irregularities in how atoms arrange themselves at the so-called "grain boundaries" - the interface where two materials meet. By describing the packing of atoms at these interfaces, the tool can be used to help researchers determine how grain boundaries affect the properties of metal alloys and other materials.

"We've known that these grain boundaries influence material characteristics for many decades," says Srikanth Patala, corresponding author of a paper on the work and an assistant professor of materials science and engineering at NC State University. "But it's been extremely difficult to understand what those defects look like at the atomic level and, therefore, to understand how these structural irregularities affect a material's strength, stiffness, ductility and so on.

"Now we have a tool that lets us see and actually understand what these disordered atomic structures really look like - and that's a big step toward figuring out exactly what's going on," Patala says.

Most materials have a particular atomic structure that is fairly regular. For example, aluminum has a cubic structure, with atoms that line up into long chains of cubes, whereas titanium forms into what are basically stacks of hexagons. But when two materials meet, such as in a metal alloy, these tidy, organized structures clash with each other, creating the disordered grain boundary.

The model developed in Patala's research group finds irregular three-dimensional shapes within the grain boundary, classifies them and then identifies patterns of those irregular shapes.

"Advances in microscopy can help us capture images of how atoms are arranged in a grain boundary, but then we don't really know what we're looking at - you can connect the dots any way you want," Patala says. "Our tool helps to discern patterns of geometric features in an atomic landscape that can appear chaotic.

"Now that these patterns can be identified, the next step is for computational researchers - like me - to work with experimental researchers to determine how those patterns affect a material's properties," Patala says.

Once the effect of the patterns is well understood, that information can be used to better identify the strengths and weaknesses of specific grain boundary types, expediting the development of new alloys or other materials.

The tool, called the Polyhedral Unit Model, can be used to model grain boundaries for any material in which the attraction between atoms is governed solely by the distance between atoms, such as metals and ionic solids - including some ceramics. However, the approach doesn't work for materials, such as carbon, that form so-called directional bonds.

"We are currently working on making the Polyhedral Unit Model publicly available through open source software," Patala says. "We plan to have it out by the end of the year, and hopefully sooner."
-end-
The paper, "A Three-Dimensional Polyhedral Unit Model for Grain Boundary Structure in fcc Metals," is published in the Nature journal npj Computational Materials. Lead author of the paper is Arash Banadaki, a postdoctoral researcher at NC State. The work was done with support from the National Science Foundation under CAREER award grant DMR-1554270.

North Carolina State University

Related Atoms Articles:

Atoms don't like jumping rope
Nanooptical traps are a promising building block for quantum technologies.
2000 atoms in two places at once
The quantum superposition principle has been tested on a scale as never before in a new study by scientists at the University of Vienna.
Single atoms as catalysts
Only the outermost layer of a catalyst can play a role in chemical reactions.
How do atoms vibrate in graphene nanostructures?
Researchers from the University of Vienna, the Advanced Institute of Science and Technology in Japan, the company JEOL and La Sapienza University in Rome have developed a method capable to measure all phonons existing in a nanostructured material.
Targeting individual atoms
In recent decades, NMR spectroscopy has made it possible to capture the spatial structure of chemical and biochemical molecules.
Manipulating atoms one at a time with an electron beam
Researchers at MIT and elsewhere have found a way to manipulate the positions of individual atoms on a graphene sheet, which could be a first step to new quantum computing and sensing devices.
What atoms do when liquids and gases meet
From the crest of a wave in the sea to the surface of a glass of water, there are always small fluctuations in density at the point where the air comes in contact with a liquid.
Manipulating single atoms with an electron beam
All matter is composed of atoms, which are too small to see without powerful modern instruments including electron microscopes.
Discovery for grouping atoms invokes Pasteur
Scientists have found a new way of joining groups of atoms together into shape-changing molecules -- opening up the possibility of a new area of chemistry and the development of countless new drugs, microelectronics and materials.
Entangled atoms shine in unison
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission.
More Atoms News and Atoms Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

In & Out Of Love
We think of love as a mysterious, unknowable force. Something that happens to us. But what if we could control it? This hour, TED speakers on whether we can decide to fall in — and out of — love. Guests include writer Mandy Len Catron, biological anthropologist Helen Fisher, musician Dessa, One Love CEO Katie Hood, and psychologist Guy Winch.
Now Playing: Science for the People

#543 Give a Nerd a Gift
Yup, you guessed it... it's Science for the People's annual holiday episode that helps you figure out what sciency books and gifts to get that special nerd on your list. Or maybe you're looking to build up your reading list for the holiday break and a geeky Christmas sweater to wear to an upcoming party. Returning are pop-science power-readers John Dupuis and Joanne Manaster to dish on the best science books they read this past year. And Rachelle Saunders and Bethany Brookshire squee in delight over some truly delightful science-themed non-book objects for those whose bookshelves are already full. Since...
Now Playing: Radiolab

An Announcement from Radiolab