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 Osaka university researchers make the slipperiest surfaces adhesive
18.10.2017 | Osaka University

nachricht Think laterally to sidestep production problems
17.10.2017 | King Abdullah University of Science & Technology (KAUST)

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Osaka university researchers make the slipperiest surfaces adhesive

18.10.2017 | Materials Sciences

Space radiation won't stop NASA's human exploration

18.10.2017 | Physics and Astronomy

Los Alamos researchers and supercomputers help interpret the latest LIGO findings

18.10.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>