Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Crystallization frustration predicts metallic glass formation

02.08.2016

Research could pave the way for new strong, conductive materials

Researchers have discovered a way to predict which alloys will form metallic glasses. The research could pave the way for new strong, conductive materials.


This is a visual representation of the difference between an organized, crystalline structure and an amorphous glass structure.

Credit: Eric Perim Martins, Duke University

Metallic glasses are sometimes formed when molten metal is cooled too fast for its atoms to arrange in a structured, crystalline order. The result is a material with numerous desirable properties. Because they are metals, metallic glasses have high hardness and toughness and good thermal conductivity. Because their structure is disorganized, they are easy to process and shape and difficult to corrode. Thanks to these characteristics, metallic glasses are used in a wide array of applications, including electrical applications, nuclear reactor engineering, medical industries, structural reinforcement and razor blades.

While metallic glass has been around for decades, scientists have no clue which combinations of elements will form them. The only way to come up with new metallic glasses to date has been to cook up new recipes in the laboratory with only a few rules of thumb for guidance and hope for the best -- a costly endeavor in both time and money.

In a new study, however, researchers from Duke University, in collaboration with groups from Harvard University and Yale University, describe a method that can predict which binary alloys will form metallic glasses. Their technique involves computing and comparing the many pockets of different structures and energies that could be found within a solidified alloy.

The results were published August 2, 2016, in Nature Communications.

"When you get a lot of structures forming next to one another that are different but still have similar internal energies, you get a sort of frustration as the material tries to crystalize," said Eric Perim, a postdoctoral researcher working in the laboratory of Stefano Curtarolo, professor of mechanical engineering and materials science and director of the Center for Materials Genomics at Duke. "The material can't decide which crystalline structure it wants to converge to, and a metallic glass emerges. What we created is basically a measure of that confusion."

To determine the likelihood of an alloy forming a glass, Curtarolo, Perim and their colleagues broke its chemistry down into numerous sections, each containing only a handful of atoms. They then turned to a prototype database to simulate the hundreds of structures each section could potentially take.

Called the AFLOW library, the database stores information on atomic structures that are commonly observed in nature. Using these examples, the program computes what a novel combination of elements would look like with these structures. For example, the atomic structure of sodium chloride -- better known as salt -- may be used to build a potential structure for copper zirconium.

These simulations produce estimations of characteristics for hundreds of structural forms that a material could take. One characteristic, called an atomic environment, looks at the geometrical arrangement of an atom's closest neighbors. Another calculates the amount of energy stored in each of these atomic structures.

To determine the likelihood of an alloy forming a metallic glass, the program compares these two characteristics between the hundreds of different structures that could be found throughout the material. If groups of atoms near one another have similar energies, they want to form similar structures. But if the rapid cooling prevents this, a metallic glass emerges.

"The big advantage to our work is that it's high-throughput, because doing this experimentally is way too time-consuming," said Cormac Toher, an assistant research professor in Curtarolo's laboratory. "You cannot check all compositions of all systems in the laboratory. That would literally take forever. The idea behind this is that we can screen a large number of materials in a couple of days and single out the most likely ones that should be checked out."

The group then put their confusion-measuring program to the test to see if it could accurately predict metallic glasses that are already known. They were able to correctly identify 73 percent -- a number they hope will improve as they continue to increase the structural information and simulations stored in their database.

Based on their initial work, they believe about one-sixth of the alloys in their system should make metallic glass. That's more than 250 potential materials, of which only about a couple dozen have been discovered.

"If you go to Venice you'll see people blowing bottles of glass," said Curtarolo. "You can do that with metallic glasses as well. You can make lightweight, very durable objects without any seams. But trying to scale these up is difficult. The larger the lump, the longer it takes its center to cool, and the more likely it is to form a normal crystalline structure. But there might be undiscovered chemical combinations that would be easier to work with, cost less, or have other, more desirable properties. We just have to figure out where to look for them."

Besides refining their results for binary alloys, the researchers plan to extend their algorithm to alloys that contain three elements, as they are more likely to form glasses but are much more difficult and time-consuming to model. Their database, however, has only about one-tenth of the entries for these alloys as it does for binary alloys, so computer clusters around the world will first need to work for some time to come.

###

This research was supported by the National Science Foundation (DMR-1436151, DMR-1436268, DMR-1435820).

CITATION: "Spectral Descriptors for Bulk Metallic Glasses Based on the Thermodynamics of Competing Crystalline Phases." Eric Perim, Dongwoo Lee, Yanhui Liu, Cormac Toher, Pan Gong, Yanglin Li, W. Neal Simmons, Ohad Levy, Joost J. Vlassak, Jan Schroers and Stefano Curtarolo. Nature Communications, Aug. 2, 2016. DOI: 10.1038/NCOMMS12315

Media Contact

Ken Kingery
Ken.kingery@duke.edu
919-660-8414

 @DukeU

http://www.duke.edu 

Ken Kingery | EurekAlert!

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Metal too 'gummy' to cut? Draw on it with a Sharpie or glue stick, science says

19.07.2018 | Materials Sciences

NSF-supported researchers to present new results on hurricanes and other extreme events

19.07.2018 | Earth Sciences

Scientists uncover the role of a protein in production & survival of myelin-forming cells

19.07.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>