Scientists create wonder alloys for aerospace industry

December 20th, 2008 - 1:38 pm ICT by IANS  

Washington, Dec 20 (IANS) Scientists have created titanium based metallic-glass composites - wonder alloys that are not only lighter, tougher and cheaper than existing compounds, but can be bent into any shape and are ideal for use in aerospace applications. Earlier this year, the work by the same Caltch (California Institute of Technology) group had resulted in “alloys with unrivaled strength and toughness,” noted Douglas Hofmann, visiting scientist and co-author of the current study.

But there were shortcomings to be overcome. Because they were created for the aerospace industry, they needed to have very lower densities.

Ideally, the alloys would have had densities in or around those of crystalline titanium alloys, which fall between 4.5 and 5 grams per cubic centimetre (g/cc), said a Caltech release.

The original alloys, made predominantly of zirconium, fell between 5.6 and 6.4 g /cc, putting them “in a no-man’s-land of densities for aerospace structures,” says Hofmann.

And so Hofmann and his colleagues–including William Johnson, Caltech’s Ruben F and Donna Mettler, professor of engineering and applied science, pioneer in the creation of metallic glass–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.

“Despite being based in titanium,” Hofmann noted, “these 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.”

This decrease in density also resulted in a reduction in cost, adds Hofmann, since zirconium is a more expensive metal than is titanium.

These findings were published online in the Proceedings of the National Academy of Sciences (PNAS) Early Edition.

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