Featured Research

from universities, journals, and other organizations

Metallic glass: How nanoscale islands react under strain

Date:
May 13, 2013
Source:
The Agency for Science, Technology and Research (A*STAR)
Summary:
High-level simulations reveal that plastic deformation in super-resilient alloys is governed by atomic zones with characteristic lengths.

High-level simulations reveal that plastic deformation in super-resilient alloys is governed by atomic zones with characteristic lengths.

Quick-cooling molten atoms give metal alloys a glassy, or random, atomic structure that generates higher elasticity and better wear- and corrosion-resistance than their crystalline alloy counterparts. However, these 'metallic glasses' also suffer from brittleness that makes them shatter. Findings from Yong Wei Zhang of the A*STAR Institute of High Performance Computing in Singapore and co-workers may now make it easier to use metallic glass in practical engineering applications. They have discovered that a fundamental relationship between material plasticity and atomic 'islands', known as 'shear transition zones' (STZs), enables precise measurement and prediction of fracturing in these materials.

When an external force strains a metallic glass, most of its atoms respond elastically and try to return to their original positions. Researchers believe that shattering occurs when STZs appear and begin to deform irreversibly. If present in high enough numbers, the STZs will generate shear bands that propagate through a cascade-like process and make the glass fracture.

Despite their importance, defining the extent of STZs remains a point of controversy among researchers. Zhang and co-workers used atomic calculations to explore the development of STZs within three metallic glasses -- iron-phosphorus (FeP), magnesium-aluminum (MgAl) and copper-zirconium (CuZr). They selected these materials because of their increasingly different 'Poisson's ratios', a mechanical constant that describes how a material 'pinches in', like a rubber band, when pulled lengthwise. Zhang and co-workers suspected that this ratio could be related to STZ formation.

They first simulated mechanical strain in each of the three types of metallic glass (see image) and observed whether the atomic movements were plastic or irreversible. Then, they correlated the plastic movements with a mathematical function based on interatomic distances. Intriguingly, they discovered that they could extract a constant 'characteristic length' parameter to measure the size of STZ islands that developed during deformation.

Zhang explains that the nanoscale lengths of STZs are reminiscent of 'defects' seen in crystalline metals, and their positive correlation with the Poisson's ratio of a material can help predict fracture problems. Their calculations showed that bigger STZ islands had more resistance to pinching in, and shattered only when relatively large shear bands formed.

By connecting basic materials physics to atomic deformation zones, the team hopes to lay the groundwork for a new generation of metallic glasses with greater resistance to brittle fracture. "Understanding the connection between Poisson's ratio, STZ size and fracture toughness is very important for the development of metallic glasses with good mechanical properties," says Zhang.


Story Source:

The above story is based on materials provided by The Agency for Science, Technology and Research (A*STAR). Note: Materials may be edited for content and length.


Journal Reference:

  1. P. Murali, Y. W. Zhang, H. J. Gao. On the characteristic length scales associated with plastic deformation in metallic glasses. Applied Physics Letters, 2012; 100 (20): 201901 DOI: 10.1063/1.4717744

Cite This Page:

The Agency for Science, Technology and Research (A*STAR). "Metallic glass: How nanoscale islands react under strain." ScienceDaily. ScienceDaily, 13 May 2013. <www.sciencedaily.com/releases/2013/05/130513114958.htm>.
The Agency for Science, Technology and Research (A*STAR). (2013, May 13). Metallic glass: How nanoscale islands react under strain. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2013/05/130513114958.htm
The Agency for Science, Technology and Research (A*STAR). "Metallic glass: How nanoscale islands react under strain." ScienceDaily. www.sciencedaily.com/releases/2013/05/130513114958.htm (accessed October 21, 2014).

Share This



More Matter & Energy News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Gulfstream G500, G600 Unveiling

Gulfstream G500, G600 Unveiling

Flying (Oct. 20, 2014) Watch Gulfstream's public launch of the G500 and G600 at their headquarters in Savannah, Ga., along with a surprise unveiling of the G500, which taxied up under its own power. Video provided by Flying
Powered by NewsLook.com
Japanese Scientists Unveil Floating 3D Projection

Japanese Scientists Unveil Floating 3D Projection

Reuters - Innovations Video Online (Oct. 20, 2014) Scientists in Tokyo have demonstrated what they say is the world's first 3D projection that floats in mid air. A laser that fires a pulse up to a thousand times a second superheats molecules in the air, creating a spark which can be guided to certain points in the air to shape what the human eye perceives as an image. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
Powered by NewsLook.com
What We Know About Microsoft's Rumored Smartwatch

What We Know About Microsoft's Rumored Smartwatch

Newsy (Oct. 20, 2014) Microsoft will reportedly release a smartwatch that works across different mobile platforms, has a two-day battery life and tracks heart rate. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins