- The Washington Times - Thursday, April 17, 2003

NAGAKUTE, Japan, April 18 (UPI) — Modern-day Japanese blacksmiths using supercomputer number crunching to guide their efforts have created novel titanium alloys possessing unprecedented strength.

The metallurgists say they are nearly capable of mass-producing their metals and now aim to use their alloys in "artificial bone or other medical equipment, sporting goods and precision parts use in outer space," materials scientist Kazuaki Nishino of Toyota Central Research and Development Laboratories in Nagakute, Japan, told United Press International.

Up to now, metalworkers have used expensive, mostly trial-and-error techniques — largely unchanged since the Bronze Age — to find desirable new alloys. The computer-aided methods used by the Japanese researchers herald a future where scientists can simply punch in numbers to get the revolutionary metals they like.

"Imagine designing a new airplane or automobile. In the end the goal is to just dial up the properties that you want for your alloy, and the computer tells you how to make it. It'd be great.

"I think we're a long way from there, but that's the goal. This new alloy will lead to these things. It opens up a whole new window to metal alloy development," said metallurgist Gary Shiflet of the University of Virginia in Charlottesville, who did not participate in the research.

A century ago at Kitty Hawk, N.C., the Wright brothers flew the first plane. It was a feat made possible with the at-the-time revolutionary motor powering the flying machine, the first gas-powered aluminum-alloy engine block. Weighing in at roughly 220 lbs., the 12-horsepower engine was nevertheless light enough to heft the heavier-than-air craft aloft.

"They did it by accidental discovery, trying alloys out by mixing them together. It's something that goes back to the Bronze Age," he explained.

Relatively simple alloys such as bronze are made by brewing two elements together and seeing if they work — copper and tin, in the case of bronze.

"Once you get to three or four elements, things get really complicated and difficult to track. It gets very expensive for industry to do this," Shiflet said. "Not only do you have to figure out what elements you have to take out of the periodic table to mix together, you have to find out precisely how much to add. Sometimes 1 percent is too much."

Since computers started becoming more widely available, scientists began tracking the effects of more and more complex alloys. "They could get up to three components, four components, five components, but they still had to do a lot of experiments to collect data," Shiflet said.

Using calculations that even a supercomputer can take weeks to perform, the Japanese researchers looked for alloys with three "magic numbers" in terms of the elemental properties of their ingredients.

"One of the magic numbers is the ratio of atoms to charge, or how many electrons each atom gives off. If you put in aluminum, it will give off maybe three electrons. That's important in how the alloy is bonded, and how its behavior changes with temperature," Shiflet said.

"Another has to do with bond lengths. Mix two elements together, they attract each other, so they get very strong bonds," he added. The final magic number dealt with atomic sizes. "Each element has a different radius, so when you mix them, they may squeeze, or rearrange to reduce strain."

After they used supercomputers to narrow down the number of choices in alloy mixes, the researchers actually brewed up these metals and experimented on them. In findings appearing in the April 18 issue of the journal Science, the research team revealed ultra-strong alloys made of six components — titanium, tantalum, niobium, vanadium, zirconium and oxygen.

While any other metal bends or breaks when experiencing forces well below theorized strength limits because of defects in their crystal structure, these new metals approach their ideal strength limits.

"You could not find this alloy just by mixing things and testing. It's just too many combinations — millions of combinations," Shiflet said.

For example, if you pulled a normal metal paper clip, its length would deform "maybe 2 or 3 percent, and then it would break," Shiflet said. These new alloys would deform "maybe 500 percent, 1,000 percent."

Moreover, the alloys are super-elastic, much like springs. Nishino said his team has already commercialized the materials with a registered brand, "Gum Metal," for eyeglass frames.

Apparently these alloys lack the defects or "dislocations" found in other metals. "The structure looks marbled," Shiflet said, referring to electron microscope pictures of the alloys.

"They described it as drawn with a hairbrush. It reminded me of piano wire — that's what piano wire looks like in cross-section, curvy and wavy. And piano wire is one of the strongest materials humans make.

"It's still not clear what happens here. This is the starting point of a lot more work," Shiflet said.

The number of potential applications is vast. "The military always wants things to be stronger and lighter," he said. "You could develop a lot of new alloys to fit these criteria, to move faster and save a lot of fuel."

Nishino said that so far the production rate of these alloys is a little over a ton a month, "and it needs several more months hereafter to establish complete quality control."

The main aim of these alloys was for car parts, but they would prove too expensive, which is why the researchers are looking for uses in medical implants and precision instruments in spacecraft.

The next step, Shiflet added, was to see if computer-aided metallurgy whips up similarly outstanding results with iron, nickel, aluminum and other key metals.

(Reported by Charles Choi, UPI Science News, in New York.)

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