Disordered materials could be hardest, most heat-tolerant carbides…and cheaper

Computational simulations predict new class of carbides that could disrupt industries from machinery to aerospace Materials scientists at Duke University and UC San Diego have discovered a new class of carbides expected to be among the hardest materials with the highest melting points in existence. Made from inexpensive metals, the new materials may soon find use in a wide range of industries from machinery and hardware to aerospace.

A carbide is traditionally a compound consisting of carbon and one other element. When paired with a metal such as titanium or tungsten, the resulting material is extremely hard and difficult to melt. This makes carbides ideal for applications such as coating the surface of cutting tools or parts of a space vehicle.

A small number of complex carbides containing three or more elements also exist, but are not commonly found outside of the laboratory or in industrial applications. This is mostly due to the difficulties of determining which combinations can form stable structures, let alone have desirable properties.

A team of materials scientists at Duke University and UC San Diego have now announced the discovery of a new class of carbides that join carbon with five different metallic elements at once. The results appear online on November 27 in the journal Nature Communications.

Achieving stability from the chaotic mixture of their atoms rather than orderly atomic structure, these materials were computationally predicted to exist by the researchers at Duke University and then successfully synthesized at UC San Diego.

“These materials are harder and lighter in weight than current carbides,” said Stefano Curtarolo, professor of mechanical engineering and materials science at Duke. “They also have very high melting points and are made out of relatively cheap material mixtures. This combination of attributes should make them very useful to a wide range of industries.”

When students learn about molecular structures, they’re shown crystals like salt, which resembles a 3-D checkerboard. These materials gain their stability and strength through regular, ordered atomic bonds where the atoms fit together like pieces of a jigsaw puzzle.

Imperfections in a crystalline structure, however, can often add strength to a material. If cracks start to propagate along a line of molecular bonds, for example, a group of misaligned structures can stop it in its tracks. Hardening solid metals by creating the perfect amount of disorder is achieved through a process of heating and quenching called annealing.





(Source/Sender: Duke University)


Leave a Reply