Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Technique creates metal memory and could lead to vanishing dents

Abstract:
Crumpled kitchen foil that lays flat for reuse. Bent bumpers that straighten overnight. Dents in car doors that disappear when heated with a hairdryer. These and other physical feats may become possible with a technique to make memory metals discovered by researchers at the University of Illinois.

Technique creates metal memory and could lead to vanishing dents

CHAMPAIGN, IL | Posted on March 29th, 2007

Normally, when a piece of metal - such as a paperclip - is bent, the change in shape becomes permanent. But, when heat is added to bent metal films having the right microstructure, the researchers found, the films return to their original shapes. The higher the temperature, the sooner the metal films revert. "It's as though the metal has a memory of where it came from," said Taher A. Saif, a professor of mechanical science and engineering at Illinois, and senior author of a paper that describes the findings in the March 30 issue of the journal Science.

In the study, Saif and graduate students Jagannathan Rajagopalan and Jong H. Han explored aluminum films and gold films. The aluminum films were 200 nanometers thick, 50-60 microns wide and 300-360 microns long. The gold films were 200 nanometers thick, 12-20 microns wide and 185 microns long. The average grain size in the aluminum films was 65 nanometers; in the gold films, 50 nanometers.

"We found that the type of metal doesn't matter, said Saif, who also is a Willett Faculty Scholar and a researcher at the university's Micro and Nanotechnology Laboratory. "What matters is the size of the grains in the metal's crystalline microstructure, and a distribution in the size."

Grain sizes are typically one-third to one-half the thickness of a metal film. Raising the temperature by about 50 degrees Celsius causes the grains to grow larger.

If the grains are uniformly too small, the metal will be brittle and break while being bent. If the grains are uniformly too large, the metal will bend, but then stay in that position. To return to the initial shape, what's needed is a balance between brittleness and malleability.

That balance can be achieved through a combination of small and large grains, the researchers report.

Variations in the microstructure lead to plastic deformation in the larger grains and elastic accommodations in the smaller grains, Saif said. The bigger grains bend, but push and pull on the smaller grains, which become elastically deformed like a spring.

If the metal is then left alone, the smaller grains will release this energy and force the bigger grains back to their original shapes over time. This local release of energy can be speeded up by applying heat.

Controlling the crystalline microstructure of thin films also could reduce energy loss in oscillators and resonators used in electronic circuits, Saif said. Oscillators and resonators are found in products ranging from air bag sensors and camcorders to digital projectors and global positioning systems.

"If the grains that constitute the metal films in these devices are between 50 and 100 nanometers, they can be very lossy," Saif said. "However, if we decrease the grain size, we can reduce much of the energy loss."

The work was funded by the National Science Foundation.

####

For more information, please click here

Contacts:
James E. Kloeppel

217-244-1073

Copyright © University of Illinois at Urbana-Champaign

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Discoveries

Heating and cooling with light leads to ultrafast DNA diagnostics July 31st, 2015

Theoretical Physicists at Freie Universität Berlin Develop New Insights into Interface between Classical and Quantum Worlds July 31st, 2015

Sol-gel capacitor dielectric offers record-high energy storage July 30th, 2015

Controlling Dynamic Behavior of Carbon Nanosheets in Structures Made Possible July 30th, 2015

Materials/Metamaterials

Nanofiltration Membrane Market 2015 - Global Industry Survey, Analysis, Size, Share, Outlook and Forecast to 2020 July 31st, 2015

Nanozirconia Market 2015 - Global Industry Survey, Analysis, Size, Share, Outlook and Forecast to 2020 July 31st, 2015

Self-Healing Nano Anti-rust Coatings Market 2015 - Global Industry Survey, Analysis, Size, Share, Outlook and Forecast to 2020 July 31st, 2015

Nanocellulose Market 2015 - Global Industry Survey, Analysis, Size, Share, Outlook and Forecast to 2020 July 31st, 2015

Announcements

Nano Spray Instrument Market 2015 - Global Industry Survey, Analysis, Size, Share, Outlook and Forecast to 2020 July 31st, 2015

Nanocellulose Market 2015 - Global Industry Survey, Analysis, Size, Share, Outlook and Forecast to 2020 July 31st, 2015

Heating and cooling with light leads to ultrafast DNA diagnostics July 31st, 2015

Theoretical Physicists at Freie Universität Berlin Develop New Insights into Interface between Classical and Quantum Worlds July 31st, 2015

Automotive/Transportation

Sol-gel capacitor dielectric offers record-high energy storage July 30th, 2015

Controlling Dynamic Behavior of Carbon Nanosheets in Structures Made Possible July 30th, 2015

Ultra-thin hollow nanocages could reduce platinum use in fuel cell electrodes July 24th, 2015

Researchers boost wireless power transfer with magnetic field enhancement July 23rd, 2015

Human Interest/Art

Pakistani Students Who Survived Terror Attack to Attend Weeklong “NanoDiscovery Institute” at SUNY Poly CNSE in Albany July 29th, 2015

Renishaw's inVia confocal Raman microscope system is being used in conservation activities at the Rijksmuseum in Amsterdam, the Netherlands June 16th, 2015

New sensing tech could help detect diseases, fraudulent art, chemical weapons June 1st, 2015

INSIDDE: Uncovering the real history of art using a graphene scanner May 21st, 2015

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project