Metallic Glass: A Revolution of Metallurgy

Using a custom-built high vacuum, high temperature viscometer, OSU materials science professor Ralf Busch (top, left) and PhD student Christopher Way are discovering new properties of bulk metallic glass.

Inside the Mechanical Engineering lab of OSU materials science professor Ralf Busch a revolution is under way. It involves a metallic material that is so unique, many researchers and industry players believe it will one day replace plastic and metals in many applications.

This material is much stronger and lighter than conventional metals, can be injection-molded like plastic, and will not corrode or rust. It's called metallic glass, and it shines like a mirror, but when you drop a piece of it to the floor, it doesn't break. In fact, it bounces--wildly--thanks to its unusual atomic structure.

"This is a revolution of metallurgy," says Busch, who is an expert on metallic glass, or liquid metal as it is sometimes called.

Conventional metals crystallize when cooled from a liquid to a solid. But metallic glass cools to an amorphous (glassy) structure, making it much stronger, lighter, and springier than other metals--and virtually corrosion-proof.

This is an important material for researchers working in the College of Engineering's ONAMI @ OSU research cluster. By pumping liquids through channels smaller than a human hair, chemical reactions become super efficient and can be better controlled. But corrosion inside the channels that are etched or cut into a metal, can be a problem. Metallic glass could be the solution.

Developed some 40 years ago, metallic glass was widely believed to not be useful in structural applications because it could only be made in thin, flimsy ribbons. Within the last 10 years, however, researchers like Busch have developed new complex alloys that form bulk metallic glass in large dimensions, so structural applications are now opening up. (The most common bulk metallic glass is an alloy made of zirconium, titanium, copper, nickel, and beryllium. It's trademark is Liquidmetal®.)

Imagine a razor blade that stays super sharp for a year. A golf club so springy it can drive a ball farther than a titanium club. An artificial hip implant that is stronger and more flexible than current implants. A cell phone case that is almost indestructible.

"In the future a ship made of bulk metallic glass could be five times larger, or weigh five times less," Busch says, explaining that bulk metallic glass is five times stronger than its crystalline counterparts.

The downside is that the materials used to make metallic glasses are expensive, but researchers are working to solve that by developing iron-based "amorphous steel," while they continue to learn about this new material. In Busch's lab, home to more than $500,000 in processing and characterization equipment, he and his graduate students recently discovered that the hot metallic glass-forming liquid behaves similar to ketchup: when shaken its viscosity is lowered. "This was a surprising discovery," Busch says. "Not what we expected, but technologically very important."

Busch did the basic research on this alloy as a post doc at Cal Tech and for the last five years at OSU. He has close to 20 years of research experience under his belt, and virtually everyone who works with amorphous metal on a scientific level knows his name. He works closely with industry partner Liquidmetal Technologies, Inc., the leading developer, manufacturer, and marketer of products made from amorphous alloys.

Busch believes metallic glass will eventually take off. After all, it took years for aluminum and plastic to catch on after they were discovered. And now they're everywhere... for the time being, at least.