Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

In metallic glasses, researchers find a few new atomic structures

14.05.2012
There are more than 5 sides to this story: In metallic glasses, researchers find a few new atomic structures

Drawing on powerful computational tools and a state-of-the-art scanning transmission electron microscope, a team of University of Wisconsin-Madison and Iowa State University materials science and engineering researchers has discovered a new nanometer-scale atomic structure in solid metallic materials known as metallic glasses.

Published May 11 in the journal Physical Review Letters, the findings fill a gap in researchers' understanding of this atomic structure. This understanding ultimately could help manufacturers fine-tune such properties of metallic glasses as ductility, the ability to change shape under force without breaking, and formability, the ability to form a glass without crystalizing.

Glasses include all solid materials that have a non-crystalline atomic structure: They lack a regular geometric arrangement of atoms over long distances. "The fundamental nature of a glass structure is that the organization of the atoms is disordered—jumbled up like differently sized marbles in a jar, rather than eggs in an egg carton," says Paul Voyles, a UW-Madison associate professor of materials science and engineering and principal investigator on the research.

Researchers widely believe that atoms in metallic glasses are arranged only as pentagons in an order known as five-fold rotational symmetry. However, in studies of a zirconium-copper-aluminum metallic glass, Voyles' team found there are clusters of squares and hexagons—in addition to clusters of pentagons, some of which form chains—all located within the space of just a few nanometers. "One or two nanometers is a group of about 50 atoms—and it's how those 50 atoms are arranged with respect to one another that's the new and interesting part," he says.

Measuring the atomic structure of glass at this scale has been extremely difficult. Researchers know that, at a few tenths of a nanometer, atoms in metallic glasses have the same distances between them as they do in crystals. They also know that at long distances—hundreds of nanometers—there's no order left. "But what happens in between, at this 'magic' length of one to three nanometers, is very hard to measure experimentally and is essentially unexplored in experiments and simulations," says Voyles.

An expert in electron microscopy, Voyles used a powerful, state-of-the-art scanning transmission electron microscope at UW-Madison as his window into this nanometer-scale atomic structure. The microscope can generate an electron probe beam two nanometers in diameter—the ideal size for examining atoms on a length scale of one to three nanometers. "And that, fundamentally, is what makes the experiments work and gives us access to this information that's otherwise very difficult to obtain," he says. "We can match our experimental probe in size right to the size of what we want to measure."

Voyles and his team coupled the experimental data from the microscope with state-of-the-art computational methods to conduct simulations that accurately reflect the experiments. "It's the combination of those two things that gives us this new insight," he says. "We can look at the results and abstract general principles about rotational symmetry and nanoscale clustering."

There were several clues in the properties of some metallic glasses that these competing geometric structures might exist. Those arise from the interrelationships of structure, processing and properties, says Voyles. "If we understand how the structure controls, for example, glass-forming ability or the ability to change shape on bending or pulling, and we understand how different elements participate in these different kinds of structures, that gives us a handle on controlling properties by adjusting the composition or adjusting the rate at which the material was cooled or heated to change the structure in some useful way," he says.

One of the unique characteristics of glasses is their ability to transition continuously from a solid to a liquid state. While other materials, when heated, are partly melted and partly solid, glasses as a whole become increasingly malleable.

While manufacturers now apply metallic glasses primarily in electrical transformer cores, their special forming capabilities may enable manufacturers to make very small, intricate parts. "Unlike conventional metallic alloys, metallic glasses can be molded like plastic—so they can be pushed or sucked or blown into very complicated shapes without any loss of material or machining," says Voyles.

Those manufacturing methods hold true even at the micro or nanoscale, so it's possible to make, for example, forests of nanowires or the world's smallest geared motor. "Five or 10 years from now, there may be more commercial applications driven by those kinds of things than there are now," he says.

For Voyles and his team, the next step will be to calculate the properties of the most realistic structural models of metallic glass they have developed to learn how those properties relate to the structure.

Other authors on the Physical Review Letters paper include lead author Jinwoo Hwang, Z.H. Melgarejo and Don Stone of UW-Madison, and Y.E. Kalay, I. Kalay and M.J. Kramer of Iowa State University.

The National Science Foundation funded Voyles' research and an NSF grant enabled him and other UW-Madison collaborators to purchase the scanning transmission electron microscope. Installed in 2010, the microscope can be operated remotely and provides UW-Madison researchers a level of instrumentation on par with the world-leading federal laboratories and research universities.

Renee Meiller, (608) 262-2481, meiller@engr.wisc.edu

Paul Voyles | EurekAlert!
Further information:
http://www.wisc.edu

More articles from Physics and Astronomy:

nachricht Meteoritic stardust unlocks timing of supernova dust formation
19.01.2018 | Carnegie Institution for Science

nachricht Artificial agent designs quantum experiments
19.01.2018 | Universität Innsbruck

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Let the good tubes roll

19.01.2018 | Materials Sciences

How cancer metastasis happens: Researchers reveal a key mechanism

19.01.2018 | Health and Medicine

Meteoritic stardust unlocks timing of supernova dust formation

19.01.2018 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>