NIST Funding for Nano-Particle Casting Technology Shows Potential for High Strength Low Weight Aluminum Alloys

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A fascinating new manufacturing concept incorporating the use of ceramic nano particles into the melt of aluminum and magnesium alloys could revolutionize the production of high strength low weight components used in a wide range of transport and defense products. So attractive is the new technology, that the National Institute of Standards and Technology (NIST) awarded $10.1 million to the team headed by the University of Wisconsin-Madison to further develop the technology.

The use of tiny ceramic particles to strengthen plastics is not new but their use in metal alloys has been held back by the fact the particles tend to clump together creating variable strength profiles from component to component. In addition, when stirred and cast as a block to gain homogeneous dispersion the resulting product is too hard to machine efficiently. A way was needed to cast in a finished shape and still maintain even dispersion. The university team has got around this by using high-intensity ultrasonic waves ” a process called cavitation ” inside the molten metal to distribute the particles. The sound waves generate bubbles that expand and contract rapidly at 20,000 cycles per second. Eventually they burst, and create a huge shock wave, according to an article in National Defense Magazine. The energy generated by that “micro nuclear bomb is enough to disperse nano-particle clusters evenly within the casting while the metal is still a liquid. So far, the team has been able to produce two-pound ingots.

The resulting material is called metal matrix nano-composites and if successful it could halve the weight and double the strength of key components used for example in mine resistant ambush protected all-terrain vehicles used by troops in Afghanistan. Not surprisingly, vehicle manufacturer Oshkosh Corporation is providing engineering resources, software and analytics to the project in an attempt to ensure its success. The key challenge seems to be in perfecting the casting process so the use of specialist casting modeling software will help to reduce experimentation by running computer models and in identifying which families of alloys will be most suited to the new technology. One major advantage of the process seems to be that casters can use existing equipment and add the cavitation ultrasound externally saving expensive re-tooling and encouraging early adoption.

The project is set to run for five years so it is unlikely we will see the technology on our family car anytime soon but should it prove as viable as early results suggest, it could open up a wide range of uses way beyond those military applications.

–Stuart Burns

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