Future tech

'Metallic glass' stronger than titanium could be used to build next-generation spacecraft

Extremely light yet incredibly strong, metallic glass is tougher than titanium and may just be the right stuff for future spacecraft

PUBLISHED : Thursday, 20 August, 2015, 7:00am
UPDATED : Friday, 21 August, 2015, 2:42am

A breakthrough discovery made by a Chinese-led international research team has raised hope for the development of a super-light, incredibly strong metal that could dramatically change the space race.

Metallic glass or amorphous metal has long been a hot candidate for next generation spacecraft construction.

The material is formed by rapidly cooling to a solid state, which gives it a random atomic structure closer to that of glass than other metals or alloys. This structure enables it to be very light but also strong, ideal for building spacecraft.

Metallic glass also has major potential for military application, some researchers believe that it could be used for developing armour-piercing projectiles capable of punching through bulletproof vests, or anti-tank rockets.

Space agencies, including Nasa in the US, have long considered using the material in many areas, ranging from spacecraft body construction and shields to protect against space debris, to future structures on the moon or Mars.

In a report released last year, Nasa's Jet Propulsion Laboratory said that "bulk metallic glasses would be the highest performing material" in many space applications "typically doubling the predicted performance of titanium".

But metallic glasses have long had a fatal flaw: they age too quickly.

When exposed to external physical stresses, metallic glasses lost their incredible physical properties, becoming crisp and fragile.

This severely limited the application of such material, especially in the space industry, where endurance and reliability are key concerns. In a paper in the journal Nature, Chinese Academy of Sciences researchers, along with colleagues from Britain and Japan, revealed they have found a solution.

That solution is, to say the least, strange.

For thousands of years, the way we have worked with metal has remained more or less the same. They are heated to a high temperature and then forged to suit the person's needs.

Metallic glasses however, are not best served by a hot oven, but by a "fridge", the researchers said.

Led by Wang Weihua of the academy's Institute of Physics in Beijing, the researchers dipped a piece of the glass in liquid nitrogen for several minutes, then lifted it up and left to warm to room temperature.

After repeating this cycle a dozen times, like a blacksmith in reverse, they finally obtained what they dubbed the "ultimate solid", a long-life metallic glass capable of withstanding the elements.

According to the researchers, the quick ageing of the glasses was caused by the "intrinsic non-uniformity of the glass structure". In other words, the randomness of atom arrangement was not random enough, with orderly structures occurring sparsely here or there.

Repeated cryonic "baths" allowed the atoms to be randomised even further, eliminating defects that would lead to the material's internal instability.

The authors said the new method was ideal for industrial adaptation and cheap mass production.

Metallic glasses are usually an alloy consisting of several metals, typically lanthanum, magnesium, zirconium, palladium, iron, copper, and titanium. The material was first developed by researchers at California Institute of Technology in the 1960s.

China is a major producer of metallic glasses, second only to the United States, according to mainland media reports. Currently the main applications are found in electric industries, where the materials are used in transformers to reduce waste heat production with their fine conductivity.

Speaking anonymously because of the sensitivity of China's space programme, one researcher warned the discovery was important but could take years before it could be tested in spaceflight, if at all.

“Many methods that work well in the lab fail to make it to the factory because of unexpected challenges that occur,” the researcher said.

If it lived up to the hype however, the material could be "game-changing", the researcher said.

"Spacecraft nowadays are heavy like pickup trucks, this would be like turning them into race cars.