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Toughest material (from 21) HEAs have been a hot area of research
since they were first developed about 20
properties. But this material is both, and years ago, but the technology required to
instead of becoming brittle at low temper- push the materials to their limits in ex-
atures, it gets tougher.” treme tests was not available until recent-
ly.
A class of metals
CrCoNi is a subset of a class of metals “The toughness of this material near liq-
called high entropy alloys (HEAs). uid helium temperatures (20 kelvin, -424
Fahrenheit) is as high as 500 megapascals
All the alloys in use today contain a high square root meters.
proportion of one element with lower
amounts of additional elements added, but In the same units, the toughness of a
HEAs are made of an equal mix of each piece of silicon is one, the aluminum air-
constituent element. frame in passenger airplanes is about 35
, and the toughness of some of the best
These balanced atomic recipes appear steels is around 100.
to bestow some of these materials with
an extraordinarily high combination of “So, 500, it’s a staggering number,” said
strength and ductility when stressed, research co-leader Robert Ritchie, a senior
which together make up what is termed faculty scientist in Berkeley Lab’s Materials
“toughness.” Sciences Division. lbl.gov
