New metal could revolutionize industry
By Fariss Samarrai
The term “cross-disciplinary research” had not crossed the minds of physicist Joe Poon or materials scientist Gary Shiflet when they first met in 1985. They just realized they had a common interest in “quasi crystals,” materials that have an unusual atomic structure.
At that first meeting, Shiflet was holding an overdue library textbook on phase transformation. Poon needed the book for a class he was teaching. They didn’t argue about it. Instead, they formed a collaboration that has continued ever since, and now includes other researchers from the College’s physics department and the materials science department at the School of Engineering and Applied Science.
“It was a natural fit for us to work together and share our knowledge and equipment and resources,” Shiflet said, “that’s why this collaboration has lasted so long.”
Besides, the two scientists like each other. “Our work has been very productive,” Poon said.
No doubt. Throughout the years, Poon and Shiflet have won several million dollars in grants for their investigations into novel materials. Early on, they received a grant from the Office of the Vice Provost for Research, who at the time was Gene Block. “That academic enhancement grant from within the University kept us going before the big government funding came,” Poon said.
As a result of years of collaborative work, the research team has discovered a nonmagnetic amorphous material that is three times stronger than conventional steel and has superior anticorrosion properties.
A future variation of this material, called DARVA-Glass 101, could be used for making ship hulls, lighter automobiles, tall buildings, corrosion-resistant coatings, surgical instruments and recreational equipment. The scientists say commercial use of the wear-resistant material could be available within three to five years.
The material, made of steel alloys that possess a randomized arrangement of atoms — thus “amorphous” steel — was discovered by modifying an earlier version of amorphous steel known as DARVA-Glass 1, first reported by Poon and Shiflet at the Fall 2002 meeting of the Materials Research Society. This past spring they reported on the more advanced DARVA-Glass 101 in the Journal of Materials Research. A variety of popular newspapers and magazines covered the discovery, including the Washington Post, the Richmond Times-Dispatch and the United Press International, and have touted the material as the next big thing in steel. Scientific American magazine recently named Poon and Shiflet to its annual list of the top 50 outstanding research leaders in science and technology for the year.
“Amorphous steels can potentially revolutionize the steel industry,” Poon said.
The Defense Department is particularly interested. The project is sponsored by the Defense Advanced Research Projects Agency, the military’s research arm that supports investigations into seemingly futuristic materials and technologies, but with very real potential for applicability in the relatively near future.
“They have very high standards for success and progress and they are mission-oriented,” Poon said.
According to Poon and Shiflet, researchers have been making amorphous steel in very small quantities for years, but have had great difficulty “scaling up” the material to sizes large enough for practical use. Poon and Shiflet have succeeded in producing large-size amorphous steel samples that can be further scaled up in industrial labs for mass production. They achieved this by adding a small dose of a rare earth element — yttrium — to create DARVA-Glass 101.
The “glass” in the material’s name refers to the frozen liquid structure of the material, somewhat similar to glass that is a liquid made solid by rapid cooling. But DARVA-Glass 101 is an aluminum-based metal composite frozen to a solid state by rapid cooling.
The team is continually varying the recipe for its materials by adding a pinch of this element, a dash of that, and by trying different heating temperatures and cooling rates. They are always tweaking the product, “trying to fool nature,” as Shiflet puts it — always seeking to come up with something better and stronger.
Most of the lab work is done by co-investigator Vijayabarathi Ponnambalam, a U.Va. materials physicist. During the last two years, the team has produced more than 100 variations of their
material on the journey toward the creation of DARVA-Glass 101.
“The problem with making a high-tech material is that, while nature gives you something, it also takes something away,” Shiflet said. “We have been able to achieve great strength and nonmagnetic properties for the material, but it is still somewhat brittle.”
They have a ways to go to achieve near perfection.
“Discovery is going on all the time,” Poon said. “We need to toughen the material more. We can always make it better.”
But discovery is not done randomly. The research team continually revises its strategies based on each new knowledge gained, and what they think may happen if they try something else — perhaps something outrageous. They also use computer models to make rational guesses about how a metal may respond to different temperatures or to the introduction of new elements.
“Unlike previous variations of amorphous steel, DARVA-Glass 101 can be produced in sizable quantities, and it can be machined as well as manipulated like a plastic. “It can be squeezed, compressed, flattened and shaped.” Poon said.
The material is of interest to the Navy for making nonmagnetic 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 also may be useful for producing lighter but harder armor-piercing projectiles. The publicly traded company Liquidmetal Technologies owns an exclusive license to the amorphous steel invented by the U.Va. scientists.