WASHINGTON, Dec. 21 (Xinhua) -- Scientists from the
California Institute of Technology have created a range of structural
metallic-glass composites, based in titanium, that are lighter and less
expensive than any the group had previously created, while still maintaining
their toughness and ductility -- the ability to be deformed without breaking.
A paper describing these breakthrough metallic-glass
alloys was published in the latest online issue of the Proceedings of the
National Academy of Sciences (PNAS).
Earlier this year, the same Caltech group had
published a paper in the journal Nature, describing new strategies for creating
the liquid-metal composites.
However, there were shortcomings to the alloys
presented in Nature. Because they were created for use in the aerospace industry
-- among other structural applications -- they needed to have very low
densities. Ideally, the alloys would have had densities in or around those of
crystalline titanium alloys, whichfall between 4.5 and 5 grams per cubic
centimeter (g/cc). The original alloys, made predominantly of zirconium, fell
between 5.6and 6.4 g/cc, putting them "in a no-man's-land of densities for
So the researchers began tweaking the components in
their composites, eventually coming up with a group of alloys with a high
percentage of titanium, but which maintained the properties of the previously
created zirconium alloys.
The scientists finally created "alloys with unrivaled
strength and toughness." "They are among the toughest engineering materials that
currently exist," lead researcher Douglas Hofmann noted.
Despite being based in titanium, these new alloys
exhibit the same impressive properties as the zirconium alloys. They are still
tough -- in other words, they resist cracking -- and they are still ductile. "In
fact, they are even more ductile than the alloys we'd created in the past," says
This decrease in density also resulted in a reduction
in cost, adds Hofmann, since zirconium is a more expensive metal than is