Revolutionary steel

Scientists at the University of Virginia have announced the discovery of a non-magnetic amorphous material that is three times stronger than conventional steel and has superior anti-corrosion properties.

Scientists at the University of Virginia (U.Va.) have announced the discovery of a non-magnetic amorphous material that is three times stronger than conventional steel and has superior anti-corrosion properties.

A future variation of the new material, called DARVA-Glass 101, could be used for making ship hulls, lighter cars, tall buildings, corrosion-resistant coatings, surgical instruments and recreational equipment. The scientists say commercial use of the material could be available within three to five years.

The material, made up of steel alloys that possess a randomised arrangement of atoms, was discovered by modifying an earlier version of amorphous steel known as DARVA-Glass 1 reported by the U.Va. researchers at the Autumn 2002 meeting of the Materials Research Society. In May of this year they reported on DARVA-Glass 101 in the Journal of Materials Research.

“Amorphous steels can potentially revolutionise the steel industry,” said Joseph Poon, professor of physics at U.Va. and principal investigator for the team that has discovered the material and is now making alterations of it for possible future use in mass production.

Poon’s U.Va. co-investigators are Gary Shiflet, professor of materials science and engineering, and Vijayabarathi Ponnambalam, materials physicist.

According to Poon, researchers have been trying for years to make amorphous steel in sizes large enough to have practical use. The U.Va researchers have succeeded in producing large-size amorphous steel samples that can be further scaled up. They achieve this by adding a small dose of a rare earth element or yttrium to DARVA-Glass 1.

The researchers believe that the large size rare earth or yttrium atom causes destabilisation of the competing crystal structure wherein the significant atomic level stress can lead to the formation of the amorphous structure. These discoveries make the U.Va. researchers optimistic that the material will be economically available within the decade.

In a separate work, a group led by C.T. Liu, a materials scientist at the Oak Ridge National Laboratory in Tennessee, has also reported on large size amorphous steel similar to DARVA-Glass 101, also by modifying the DARVA-Glass 1 discovered by the U.Va scientists.

Poon said the amorphous steel is extremely strong, but brittle in its current state. “We need to toughen the material more,” he said. “We can always make it better.”

According to the U.Va. researchers, amorphous steel can be machined as well as manipulated like a plastic. “It can be squeezed, compressed, flattened and shaped,” said Poon.

The material is of particular interest to the US Navy for making non-magnetic ship hulls, particularly for submarines, which are detectable by the magnetic field of their hulls. The amorphous steel that the U.Va. team is refining is non-magnetic, potentially making a ship invisible to magnetism detectors and mines that are detonated by magnetic fields. The new material also may be useful for producing lighter but harder armour-piercing projectiles.