Strongest metal alloy

It could be the new superhero of metals. More than twice as strong as titanium and steel, it doesn’t rust and it can be cast like plastic and honed to an edge as sharp as glass. And like any superhero, it has a weakness: don’t heat it too much, or it loses its strength.

THE FRUIT of a 1992 discovery at the California Institute of Technology, the alloy, called Liquidmetal, has already been used in golf clubs. And it may soon show up in cell phone casings, baseball bats and scalpels.

Liquidmetal Technologies, the Lake Forest, Calif. company that is trying to commercialize the alloy, is not shy about calling it revolutionary.

“It combines uniquely a material with exceptional properties and the ability to process the material to exceptional shapes,” says Dr. Michael Ashby, professor of engineering at Cambridge University in Britain and an advisor to the company.

Liquidmetal’s surprising properties come of a structure different from ordinary metals.

When a conventional metal cools, it forms grains, each a small crystal where the atoms are oriented in a grid. The boundaries between these grains are a metal’s weak points — it’s where cracks can form and rust starts, for instance.

Scientists discovered in 1959 that if some alloys are cooled very quickly the atoms don’t have time to form crystals. Instead, they remain jumbled, as in a liquid or in glass.

However, the only way to cool the molten metal fast enough was to make it in thin strips or as a sprayed coating. The strips couldn’t be joined, because they were hard to forge, and heat allowed the atoms to crystallize again.

Because of their unique magnetic properties, the strips are still found in the anti-theft tags used by retail stores and in electrical transformers. The metal was also used to spray-coat oil drill pipes to protect them from wear.

In 1992, Dr. William Johnson and Dr. Atakan Pekers at the Caltech discovered a way around the cooling problem.

They made an alloy of elements that fit very poorly together: titanium, copper, nickel, zirconium and beryllium. These elements’ atoms are of different sizes so they don’t readily form crystals, even when cooled slowly. Pieces up to an inch thick could now be made.

Liquidmetal Technologies seized on the opportunity, and together with Caltech and Howmet Metal Mold of Whitehall, Mich., developed casting techniques.

FROM GOLF CLUBS TO CELL PHONES

In the mold, Liquidmetal reveals another quality: it doesn’t shrink when it solidifies. Ordinary metals do, meaning the product is rough out of the mold and needs machining.

“What happens with Liquidmetal, in essence, is that you can form parts sort of the way you form plastics,” says John Kang, chief executive of Liquidmetal Technologies.

Liquidmetal can be cast with a precision down to 1 micron, or 1/25,000th of an inch, according to Johnson, now an advisor to Liquidmetal Technologies. Given a good die, it is possible to cast a scalpel blade and have it come sharp out of the mold.

Liquidmetal Technologies’ first product was golf club heads, because of another exotic property of the metal: it transfers more of the club’s energy to the ball than steel or titanium, at least in theory.

But golf equipment is a fiercely competitive field, and Liquidmetal has since decided to stop making its own clubs and is working instead with major golf club manufacturers because, in Kang’s words “we came to the realization that we are not in the consumer products industry.” At the same time, it is looking to expand the uses for the alloy. Using money from an initial public offering in May, it is building a factory in South Korea to make, primarily, casings for cell phones.

While cell phones are not the first use that comes to mind for a super-strong metal, Kang says Liquidmetal’s strength and ease of casting makes it ideal.

“Cell phone makers want to go smaller and thinner ... we create an ability for cell phones to be smaller than any other material,” he says. The project has attracted interest from cell phone giants Motorola and Samsung.

Liquidmetal Technologies is also working with Rawlings on baseball bats and HEAD on skis, for much the same reason they tried their hand on golf clubs — Liquidmetal gives good bounce.

The Defense Advanced Research Projects Agency is also investigating several different uses of the alloy. One project is looking at using it in armor-piercing shells as a replacement for depleted uranium, which has been a focus of health and environmental concerns.

HEAT, COST AT ISSUE

For all its promise, Liquidmetal is still largely untried, which is why the company is concentrating on industries where there is a readiness to explore the new.

John Perepezko, professor of materials science at the University of Wisconsin, says making sports equipment is a safer place to start, than, for instance, the aircraft industry.

“Nobody is going to fall out of the sky, no ship is going to sink if you make a mistake,” he says. “If you break a golf club, you usually brag about being too strong, rather than blame it on a weak club.”

Then there’s the issue of heat.

Much like glass, Liquidmetal softens when heated — the earliest alloy at about 750 degrees Fahrenheit. By comparison, steel becomes malleable at about 2,100 degrees. Some newer amorphous alloys are, however, much more resistant to heat, Johnson says.

Cost also limits Liquidmetal. The raw materials run at $10 to $15 a pound, about as much as titanium, while aluminum costs about 50 cents a pound.

Caltech researchers are trying to create alloys consisting of cheaper metals.

“If we can make a processable amorphous iron alloy with a raw material cost of a dollar a pound, it could be an enormously pervasive material,” Johnson says. “It could even make its way into cars.”

Perepezko, who is not affiliated with Liquidmetal Technologies, believes that even at its present cost, the alloy is likely to see widespread use once its reliability has been proven.

“It’s not going to replace the aluminum in soda cans, it just doesn’t work that way. But in critical applications, it will happen. Perhaps the most important use out there is one we can’t imagine yet,” he says.

The Original Story from: msnbc