Featured Research

from universities, journals, and other organizations

Materials science: Perfecting the defect

Date:
May 7, 2012
Source:
The Agency for Science, Technology and Research (A*STAR)
Summary:
Simulations of defects inside copper point the way to making stronger metals. Results show that there are many different deformation mechanisms occurring in nano-structured materials like nanotwinned copper. Understanding each of them will allow scientists to tune material properties.

The image shows the simulation of a polycrystalline nanotwinned copper and its defects during tensile loading.
Credit: Copyright 2011 Elsevier

Simulations of defects inside copper point the way to making stronger metals. Results show that there are many different deformation mechanisms occurring in nano-structured materials like nanotwinned copper. Understanding each of them will allow scientists to tune material properties.

Strong metals have a tendency to be less ductile -- unless the metal happens to be a peculiar form of copper known as nanotwinned copper. The crystal structure of nanotwinned copper exhibits many closely-spaced interruptions in an otherwise regular atomic array. These interruptions, despite being termed 'defects', actually increase the metal's strength without reducing its ductility, making it attractive for applications such as semiconductor devices and thin film coatings. However, the relationship between the properties of these defects and those of the metals containing defects remains unclear.

Now, Zhaoxuan Wu and co-workers at the A*STAR Institute for High Performance Computing have now performed a large-scale numerical simulation that sheds light on this relationship. The simulation addressed some of their previous, unexplained experimental data.

In 2009, the researchers had observed that the strength of nanotwinned copper reached a maximum when the size of the defects in its crystal structure was about 15 nanometers. When the defects were made smaller or larger, the copper's strength decreased. This contradicted the classical model, which predicted that the metal's strength would increase continually as the defect size was reduced.

Wu and co-workers addressed this contradiction by using a very large-scale molecular dynamics simulation to calculate how a nanotwinned copper crystal consisting of more than 60 million atoms deforms under pressure. They observed that its deformation was facilitated by three types of mobile dislocations in its crystal structure. Significantly, they found that one of these three types of dislocation, called a 60 dislocation, interacted with defects in a way that depended on the defect size.

The 60 dislocations were able to pass through small defects in a continuous manner, creating many new, highly mobile dislocations that softened the copper. On the other hand, when they encountered large defects, a three-dimensional dislocation network formed that acted as a barrier for subsequent dislocation motion, thus strengthening the copper. The simulation predicted that the critical defect size separating these two regimes of behavior occurred at 13 nanometers, very close to the experimentally measured value of 15 nanometers.

The results show that there are many different deformation mechanisms occurring in nano-structured materials like nanotwinned copper. Understanding each of them will allow scientists to tune material properties -- as Wu comments: "For example, we could introduce dislocation barriers to stop their motion, or change defect interface energies to change how they deform." Wu adds that the next step for his research team will be to take into account the diversity in defect sizes within a single material.


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. Z.X. Wu, Y.W. Zhang, D.J. Srolovitz. Deformation mechanisms, length scales and optimizing the mechanical properties of nanotwinned metals. Acta Materialia, 2011; 59 (18): 6890 DOI: 10.1016/j.actamat.2011.07.038

Cite This Page:

The Agency for Science, Technology and Research (A*STAR). "Materials science: Perfecting the defect." ScienceDaily. ScienceDaily, 7 May 2012. <www.sciencedaily.com/releases/2012/05/120507100918.htm>.
The Agency for Science, Technology and Research (A*STAR). (2012, May 7). Materials science: Perfecting the defect. ScienceDaily. Retrieved April 19, 2014 from www.sciencedaily.com/releases/2012/05/120507100918.htm
The Agency for Science, Technology and Research (A*STAR). "Materials science: Perfecting the defect." ScienceDaily. www.sciencedaily.com/releases/2012/05/120507100918.htm (accessed April 19, 2014).

Share This



More Matter & Energy News

Saturday, April 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Small Reactors Could Be Future of Nuclear Energy

Small Reactors Could Be Future of Nuclear Energy

AP (Apr. 17, 2014) After the Fukushima nuclear disaster, the industry fell under intense scrutiny. Now, small underground nuclear power plants are being considered as the possible future of the nuclear energy. (April 17) Video provided by AP
Powered by NewsLook.com
Horseless Carriage Introduced at NY Auto Show

Horseless Carriage Introduced at NY Auto Show

AP (Apr. 17, 2014) An electric car that proponents hope will replace horse-drawn carriages in New York City has also been revealed at the auto show. (Apr. 17) Video provided by AP
Powered by NewsLook.com
Honda's New ASIMO Robot, More Human-Like Than Ever

Honda's New ASIMO Robot, More Human-Like Than Ever

AFP (Apr. 17, 2014) It walks and runs, even up and down stairs. It can open a bottle and serve a drink, and politely tries to shake hands with a stranger. Meet the latest ASIMO, Honda's humanoid robot. Duration: 00:54 Video provided by AFP
Powered by NewsLook.com
German Researchers Crack Samsung's Fingerprint Scanner

German Researchers Crack Samsung's Fingerprint Scanner

Newsy (Apr. 16, 2014) German researchers have used a fake fingerprint made from glue to bypass the fingerprint security system on Samsung's new Galaxy S5 smartphone. 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:
from the past week

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