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 Researchers shoot for success with simulations of laser pulse-material interactions
29.03.2017 | DOE/Oak Ridge National Laboratory

nachricht Nanomaterial makes laser light more applicable
28.03.2017 | Christian-Albrechts-Universität zu Kiel

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers shoot for success with simulations of laser pulse-material interactions

29.03.2017 | Materials Sciences

Igniting a solar flare in the corona with lower-atmosphere kindling

29.03.2017 | Physics and Astronomy

As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

29.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>