Brittle materials can be made stronger by shrinking them to nanoscale size

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Washington, Feb 10 (ANI): Scientists at the California Institute of Technology (Caltech) have determined that some notoriously brittle materials can be made stronger by simply reducing them to nanoscale size.he work, by Dongchan Jang, senior postdoctoral scholar, and Julia R. Greer, assistant professor of materials science and mechanics at Caltech, could eventually lead to the development of innovative, superstrong, yet light and damage-tolerant materials.

These new materials could be used as components in structural applications, such as in lightweight aerospace vehicles that last longer under extreme environmental conditions and in naval vessels that are resistant to corrosion and wear.

"Historically, structural materials have always had to rely on their processing conditions, and thereby have been 'slaves' to their properties," said Greer.

These materials are very heavy, which is problematic for many applications, and they are extremely brittle, which is less than ideal for supporting heavy loads.

In fact, "they fail catastrophically under mechanical loads," said Greer.

Metals and alloys, on the other hand, are ductile, and therefore unlikely to shatter, but lack the strength of ceramics.

Materials scientists have developed an intriguing class of materials called glassy metallic alloys, which are amorphous and lack the crystalline structure of traditional metals.

The materials, also known as metallic glasses, are composed of random arrangements of metallic elements like zirconium, titanium, copper, and nickel.

According to Greer, they are lightweight-a "huge advantage" for their incorporation into new types of devices, and yet are comparable in strength to ceramics.

Unfortunately, their random structure makes metallic glasses quite brittle.

"They also fail catastrophically under tensile loads," she said.

But now, Greer and Jang have developed a strategy to overcome these obstacles-by making metallic glasses that are almost vanishingly small.

The scientists devised a process to make zirconium-rich metallic glass pillars that are just 100 nanometers in diameter-roughly 400 times narrower than the width of a human hair.

At this size, "the metallic glasses become not only even stronger, but also ductile, which means they can be deformed to a certain elongation without breaking. Strength plus ductility represents a very lucrative combination for structural applications," said Greer.

As yet, there are no immediate applications for the new materials, although it may be possible to combine the nanopillars into arrays, which could then form the building blocks of larger hierarchical structures with the strength and ductility of the smaller objects.

The work, however, "convincingly shows that 'size' can be successfully used as a design parameter," Greer said. (ANI)

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