A team led by researchers at the University of California Los Angeles has created a structural metal composed of magnesium infused with ceramic silicon carbide nanoparticles. The resulting material has a high stiffness-to-weight ratio, which the team says is useful in making lighter cars, as well as in mobile electronics and biomedical devices.

To create the metal, the team found a way to disperse and stabilize nanoparticles in molten metals. Specifically, they infused a large number of silicon carbide particles smaller than 100 nanometers into magnesium. This added strength, stiffness, plasticity and durability under high temperatures. They also developed a scalable manufacturing method that could pave the way for more high-performance lightweight metals.

A deformed sample of pure metal (left) and the new metal (right). Image credit: UCLA Scifacturing Laboratory.A deformed sample of pure metal (left) and the new metal (right). Image credit: UCLA Scifacturing Laboratory.Ceramic particles have long been considered as a potential way to make metals stronger. However, with microscale ceramic particles, the infusion process results in a loss of plasticity. Nanoscale particles, by contrast, can enhance strength while maintaining or even improving metals’ plasticity. However, nanoscale ceramic particles tend to clump together rather than disperse evenly. This is due to the tendency of small particles to attract one other.

To counteract this, the researchers dispersed the particles into a molten magnesium zinc alloy. The nanoparticle dispersion relies on the kinetic energy in the particles’ movement. This stabilizes the particles’ dispersion and prevents clumping. To further enhance the new metal’s strength, the researchers used a technique called high-pressure torsion to compress it.

The new metal silicon carbide-infused magnesium nanocomposite is around 14% silicon carbide nanoparticles and 86% magnesium. According to the researchers, it demonstrates record levels of specific strength—the weight a material can withstand before breaking—and specific modulus, the material’s stiffness-to-weight ratio. It also showed what they say is superior stability at high temperatures.

“It’s been proposed that nanoparticles could really enhance the strength of metals without damaging their plasticity, especially light metals like magnesium, but no groups have been able to disperse ceramic nanoparticles in molten metals until now,” says Xiaochun Li, the principal investigator on the research.

“With an infusion of physics and materials processing, our method paves a new way to enhance the performance of many different kinds of metals by evenly infusing dense nanoparticles to enhance the performance of metals to meet [today's] energy and sustainability challenges.”

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