Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Ductile intermetallic compounds discovered

16.09.2003


Ames Laboratory researchers identify non-brittle intermetallics



To material scientists the phrase "ductile intermetallic compounds" has long been considered an oxymoron. Although these compounds possess chemical, physical, electrical, magnetic, and mechanical properties that are often superior to ordinary metals, their potential has gone untapped because they are typically quite brittle at room temperature. Until now.

Researchers at the U.S. Department of Energy’s Ames Laboratory at Iowa State University have discovered a number of rare earth intermetallic compounds that are ductile at room temperature. The discovery, announced in an article in the September issue of the journal Nature Materials, 2, PP 587-590, has the potential to make these promising materials more useful.


"Over the last several decades, tens of thousands of intermetallics have been identified," Ames Laboratory materials scientist Alan Russell said. "But in order to make them even somewhat ductile, a whole menu of ’tricks’ have been developed, such as testing them at high temperatures, or in zero-humidity, or shifting them off stoichiometry. The materials we’re studying are the first ones that don’t need these contrivances."

So far, the Ames Laboratory research team, led by senior metallurgist Karl Gschneidner, Jr. and Russell, has identified 12 fully ordered, completely stoichiometric intermetallic compounds. These compounds are formed by combining a rare earth element with certain main group or transition metals . The resulting binary compounds have a B2 crystal structure, like that found in cesium-chloride (CsCl), in which an atom of one element is surrounded by a cubic arrangement of eight atoms of the other element.

The study has focused on yttrium-silver (YAg), yttrium-copper (YCu), and dysprosium-copper (DyCu), but a preliminary examination of other rare earth compounds showed that cerium-silver (CeAg), erbium-silver (ErAg), erbium-gold (ErAu), erbium-copper (ErCu), erbium-iridium (ErIr), holmium-copper (HoCu), neodymium-silver (NdAg), yttrium-indium (YIn), and yttrium-rhodium (YRh) are also ductile.

Samples were prepared by arc-melting high-purity elements to form compounds with a 50-50 atomic mix of Y or Dy and Ag or Cu. X-ray diffraction, optical metallography, and electron microscopy confirmed the specimens were single-phase with the fully ordered B2 structure.

In tensile testing, these materials showed remarkable ductility. The YAg stretched nearly 25 percent before it fractured, compared to 2 percent or less for many other intermetallics. In other measurements, the materials showed ASTM fracture toughness values (KIC) comparable with commercial aircraft aluminum alloys.

Why these materials deform while other intermetallics shatter isn’t quite clear, but theoretical calculations by Ames Lab physicist James Morris show that the ductile materials possess much lower unstable stacking-fault energies. Because these energies are lower in the ductile materials, it is easier for them to plastically deform instead of fracturing at the grain boundaries.

"There are particular planes (within the B2 structure) that tend to slip most easily," Russell said, "and particular directions on those planes where deformation slip occurs most easily. However, our transmission electron micrographs identify slippage in more than one direction, so there are probably other factors at work as well."

While there may be applications for these ductile materials because of their other characteristics like high-temperature strength or corrosion resistance, Gschneidner and Russell hope that studying these materials will actually lead to a better understanding of the brittle intermetallics.

"The most exciting thing about this is finding a material that breaks all the rules. It provides a great opportunity to figure out fundamentally why the others are brittle," Russell said. "To see one that’s the exception gives you a new perspective on all the others."

Gschneidner added, "The exceptions are the ones you want to concentrate on because they can tell you a heck of a lot more than all the ones that obey the rules. It can steer you in a whole new direction."



The research is supported through funding from the DOE’s Office of Basic Energy Science. The Ames Laboratory is operated for the Department of Energy by ISU. The Laboratory conducts research into various areas of national concern, including energy resources, high-speed computer design, environmental cleanup and restoration, and the synthesis and study of new materials. More information about the Ames Laboratory can be found at www.ameslab.gov.

Note to editors: For images showing the material, tensile test results, or the scientists, please contact Kerry Gibson, kgibson@ameslab.gov.

Kerry Gibson | EurekAlert!
Further information:
http://www.external.ameslab.gov/
http://www.ameslab.gov

More articles from Materials Sciences:

nachricht Carnegie Mellon researchers create soft, flexible materials with enhanced properties
24.05.2019 | Carnegie Mellon University

nachricht Plumbene, graphene's latest cousin, realized on the 'nano water cube'
23.05.2019 | Nagoya University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: New studies increase confidence in NASA's measure of Earth's temperature

A new assessment of NASA's record of global temperatures revealed that the agency's estimate of Earth's long-term temperature rise in recent decades is accurate to within less than a tenth of a degree Fahrenheit, providing confidence that past and future research is correctly capturing rising surface temperatures.

The most complete assessment ever of statistical uncertainty within the GISS Surface Temperature Analysis (GISTEMP) data product shows that the annual values...

Im Focus: The geometry of an electron determined for the first time

Physicists at the University of Basel are able to show for the first time how a single electron looks in an artificial atom. A newly developed method enables them to show the probability of an electron being present in a space. This allows improved control of electron spins, which could serve as the smallest information unit in a future quantum computer. The experiments were published in Physical Review Letters and the related theory in Physical Review B.

The spin of an electron is a promising candidate for use as the smallest information unit (qubit) of a quantum computer. Controlling and switching this spin or...

Im Focus: Self-repairing batteries

UTokyo engineers develop a way to create high-capacity long-life batteries

Engineers at the University of Tokyo continually pioneer new ways to improve battery technology. Professor Atsuo Yamada and his team recently developed a...

Im Focus: Quantum Cloud Computing with Self-Check

With a quantum coprocessor in the cloud, physicists from Innsbruck, Austria, open the door to the simulation of previously unsolvable problems in chemistry, materials research or high-energy physics. The research groups led by Rainer Blatt and Peter Zoller report in the journal Nature how they simulated particle physics phenomena on 20 quantum bits and how the quantum simulator self-verified the result for the first time.

Many scientists are currently working on investigating how quantum advantage can be exploited on hardware already available today. Three years ago, physicists...

Im Focus: Accelerating quantum technologies with materials processing at the atomic scale

'Quantum technologies' utilise the unique phenomena of quantum superposition and entanglement to encode and process information, with potentially profound benefits to a wide range of information technologies from communications to sensing and computing.

However a major challenge in developing these technologies is that the quantum phenomena are very fragile, and only a handful of physical systems have been...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

SEMANTiCS 2019 brings together industry leaders and data scientists in Karlsruhe

29.04.2019 | Event News

Revered mathematicians and computer scientists converge with 200 young researchers in Heidelberg!

17.04.2019 | Event News

First dust conference in the Central Asian part of the earth’s dust belt

15.04.2019 | Event News

 
Latest News

On Mars, sands shift to a different drum

24.05.2019 | Physics and Astronomy

Piedmont Atlanta first in Georgia to offer new minimally invasive treatment for emphysema

24.05.2019 | Medical Engineering

Chemical juggling with three particles

24.05.2019 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>