Breakthrough in magnesium research

Lighter, more fuel efficient cars are now a possibility due to research on enhancing magnesium’s corrosion resistance in Sweden.

Magnesium is the lightest metal used in construction but is also the most reactive, making it very sensitive to corrosion; this has prevented magnesium being used in cars.

Mohsen Esmaily, from the Chalmers University of Technology in Sweden, said: “In cars where every kilo of reduced weight is important, a transition to magnesium, which is 30 percent lighter than the most common lightweight metal today, aluminium, would mean a great step forward to reduce fuel consumption.”

Efforts to lower the reactivity of magnesium have included a variety of coatings and new corrosion-resistant alloys. By manipulating the microstructure, Esmaily managed to increase corrosion resistance.

Magnesium casts produced through rheocasting were found to be up to four times more resilient than magnesium produced by high pressure die casting. The method of casting creates semi-solid slurry from heating raw materials which is then pushed it into a mould and cooled.

Rheocasting magnesium alloys was originally developed to increase the materials strength but Esmaily found it also gives the alloys increased corrosion resistance.

Further research will now go into optimising the microstructure to improve corrosion resistance.

Esmaily said: “We will be able to create cast magnesium alloys that corrode much slower and that are stronger than ever before by controlling the microstructure of the alloy.”

The research was published in Corrosion Science.