More Deformation than Expected Found in Yield Studies

[nanoorg]

Researchers Find More Deformation than Expected in Yield Studies


U.S. scientists are taking another look at the deformation of nanoscale materials, which don't always have the same properties they would in bulk.

Scientists have assumed a crystal needs to be perfect to sustain stress at its theoretical limit. Beyond that point dislocations in the crystal lattice occur and the crystal undergoes a non-reversible change of shape, or plastic deformation.

Now a team from the U.S. Department of Energy's Lawrence Berkeley National Laboratory, Purdue University, and Hysitron Inc. in Minneapolis has found things don't necessarily happen that way.

"Although it's been assumed that you need a perfect volume of material to reach the ideal strength, our results show this is not always true," said lead researcher Andrew Minor of Berkeley Lab's Materials Sciences Division. "The situation is more complex. We found that plenty of defects accumulate before the point that would usually be interpreted as the initial yield point."

The study is available at the Web site of the journal Nature Materials.


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Source: http://www.smalltimes.com/


This story was first posted on 15th August 2006.