A team led by researchers from the UCLA Henry Samueli School of Engineering and Applied¹ Science has created a super-strong yet light structural² metal with extremely high specific strength and modulus, or stiffness-to-weight ratio. The new metal is composed of magnesium³ infused with a dense⁴ and even dispersal of ceramic⁵ silicon⁶ carbide nanoparticles. It could be used to make lighter⁷ airplanes, spacecraft, and cars, helping⁸ to improve fuel efficiency, as well as in mobile electronics and biomedical devices. To create the super-strong but lightweight metal, the team found a new way to disperse⁹ and stabilize¹⁰ nanoparticles in molten metals. They also developed a scalable manufacturing method that could pave the way for more high-performance lightweight metals. The research was published today in Nature. 

 

"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," said Xiaochun Li, the principal investigator¹¹ on the research and Raytheon Chair in Manufacturing Engineering at UCLA. "With an infusion¹² 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 energy and sustainability challenges in today's society." 

 

Structural metals are load-bearing metals; they are used in buildings and vehicles. Magnesium, at just two-thirds the density¹³ of aluminum¹⁴, is the lightest structural metal. Silicon carbide is an ultra-hard ceramic commonly used in industrial cutting blades. The researchers' technique of infusing a large number of silicon carbide particles smaller than 100 nanometers into magnesium added significant strength, stiffness, plasticity and durability¹⁵ under high temperatures.

 

The researchers' new silicon carbide-infused magnesium demonstrated record levels of specific strength -- how much weight a material can withstand before breaking -- and specific modulus -- the material's stiffness-to-weight ratio. It also showed superior stability at high temperatures.

 

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. But nanoscale ceramic particles tend to clump¹⁶ together rather than dispersing¹⁷ evenly, due to the tendency of small particles to attract one other.

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