https://www.space.com/toughest-material-nickel-cobalt-chromium-alloy

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Strange alloy

The chromium, cobalt and nickel alloy is an example of a high entropy alloy (HEA). Unlike most alloys, which are made predominantly of one element with lower amounts of additional elements added, HEAs are made of an equal mix of each constituent element.

This HEA is extremely malleable, or ductile, meaning it can bend under pressure to withstand fracturing, according to the study authors. Several quirks of the alloy's molecular structure make it so extraordinarily malleable. One key mechanism, for example, causes atoms within the alloy to dislocate under pressure, allowing them to shear over one another. This, along with various other mechanisms, allow the material to keep deforming as pressure increases, without fracturing or breaking.

"Each one of these mechanisms kicks in at a later stage when you increase the strain on the material and that's the perfect recipe for high toughness," Ritchie added. "What is remarkable is these mechanisms get more effective in colder temperatures."

The researchers initially tested the alloy's toughness by exposing it to liquid nitrogen at temperatures of around minus 321 degrees Fahrenheit (minus 196 degrees Celsius). When the alloy's toughness only improved, the team wondered how much further they could push the material's limits.

Dong Liu, a physicist at Bristol University in England, and colleagues designed an experiment to expose the alloy to liquid helium, which can cool to super-frigid temperatures of minus 424 F (minus 253 C). The team then watched neutrons scatter off the material in a process called neutron diffraction to peer into the structure of the alloy and see how cracks formed as pressure increased.

The experiment showed that when it came to toughness, the alloy blew graphene out of the water.

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