A new understanding of the microscopic changes that take place when molten alloys cool could be useful for improving aluminum recycling technology, say researchers from the University of Birmingham and University of Greenwich in England.
Andrew Kao from the University of Greenwich developed a mathematical model to predict that helical (screw-shaped) micro-crystals would form as alloys cool and solidify under a magnetic field. Biao Cai from the University of Birmingham’s School of Metallurgy and Materials used high-speed X-ray imaging to record the formation of those micro-crystals, confirming the prediction. The microscopic crystals are 10 times smaller than a human hair, but their shape determines the physical properties the alloy will have, researchers say. This research could help manufacturers adjust an alloy’s shape, structure, and direction of crystal growth, they say.
Biao has also invented a technique to remove iron from secondary aluminum, the University of Birmingham says. The inexpensive technique uses magnets and a temperature gradient to remove the iron contamination, which can make aluminum brittle. The university has patented the technique and is in the process of building a large-scale prototype with support from the Midlands Innovation Commercialisation of Research Accelerator, the university says. Visit www.birmingham.ac.uk/schools/metallurgy-materials.