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Metallic glass parts can now be created in milliseconds

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May 16, 2011

A metallic glass rod before heating and molding (left); a molded metallic glass part (middle); the final product with its excess material trimmed off (right) (Photo: Marios D. Demetriou)

A metallic glass rod before heating and molding (left); a molded metallic glass part (middle); the final product with its excess material trimmed off (right) (Photo: Marios D. Demetriou)

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What do you do if you want a material that's as hard as glass, but that can bend without shattering, like steel? Well, if you're a researcher at the California Institute of Technology (Caltech), you invent metallic glass. There are several types of metallic glass – which is said to be stronger than steel or titanium – all of which consist of a metal with the disordered atomic structure of glass. Although it's been possible to produce the material in bulk since the early 90s, the production process has limitations, that have kept metallic glass from coming into common use. Now, however, a Caltech team has come up with a new process, in which the material can be shaped as easily as plastic.

In the conventional method of shaping metallic glass, the solid alloy must first be heated to over 1000C (1832F). This liquefies it, and puts it comfortably above its transition phase temperature of 500-600C (932-1112F), below which it begins to crystallize. Once liquefied, it is then poured into metal molds, where it cools before crystallizing and becoming a solid again.

Unfortunately, however, such molds are typically only designed to withstand temperatures up to 600C. Being repeatedly exposed to the 1000-degree liquid is hard on them, and as a result, they need to be frequently replaced. The liquid metallic glass is also fluid enough that it has a tendency to splash and break up when being poured, which results in finished cooled parts with structural defects.

In order to address these problems, the Caltech researchers have utilized a process known as ohmic heating. Using it, they fired an electrical pulse of over 1,000 joules in about 1 millisecond (which is around one megawatt of power), into a 20 x 4 mm metallic glass rod. This heated it to around 550C (1022F) in approximately half a millisecond, at which point it became liquefied, but was still very close to its transition phase. This was not a problem, however, as it was then immediately injected into a mold and cooled. The entire shaping process took less than 40 milliseconds, and resulted in a structurally-sound metallic glass toroid – a donut-shaped object.

The technology is called rapid discharge forming. It has been patented, and is now being developed for commercialization by the Caltech spin-off company Glassimetal Technology.

The research was published last week in the journal Science.

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About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away. All articles by Ben Coxworth
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8 Comments

This is a game-changer... nice work! Would love to see a video of this.

Matt Rings

I know there are a few types, but what about weight versus iron and aluminum?

PrometheusGoneWild.com

I would love to see a video to.. but seeing that the molding process too 40 milli seconds and I am guessing it a machine we wouldnt really see a whole lot. Also I imagine even a picture of the machine would give away proprietary information so we will just have to settle for the freaking cool picture.

I have been hearing about super cool liquid metals for some time.

My only question is if they can give me claws like wolverine?? jk.

Michael Mantion

A very interesting material. I have an idea for a modification to the process. I guess I can contact someone at Glassimetal Technology?

WildZBill

I would love to have some examples of where the average everyday person would encounter something that was made that had magnetic glass in it...I mean, what\'s the point of spending all this time and effort to make something that nobody uses...

Ed

So , what do you think is next ? Transparent Aluminum ?

Jim Andrews

Jim, In a broad sense, the name of your transparent aluminum is \"spinel\" - it is being developed for among other things, transparent armor utilized in mobile applications.

Richard Newcombe

Too late, Jim - transparent Aluminum has been around for a while, tested by the Air Force in 2005: http://science.howstuffworks.com/transparent-aluminum-armor.htm

Yarko
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