Magnesium is the lightest construction metal, but also the most reactive. This means that it is very sensitive to corrosion, making it difficult to use in corrosive environments. For more than a hundred years, magnesium producers have strived to improve its corrosion characteristics by developing new, more corrosion-resistant alloys, and developing various coatings.
Mohsen Esmaily, a researcher in Atmospheric Corrosion at Chalmers University of Technology, has changed the microstructure in magnesium alloys to make them more resistant to corrosion. This could encourage the transport sector to use these materials to decrease the weight of vehicles.
Esmaily said: “In cars where every kilo of reduced weight is important, a transition to magnesium, which is 30% lighter than aluminium, the most common lightweight metal today, would mean a great step forward to reduce fuel consumption.”
By studying magnesium casts produced through a method called rheocasting, Esmaily discovered that the corrosion resistance of magnesium alloys produced this way was up to four times better than the same material when produced by conventional high pressure die casting.
Rheocasting of magnesium alloys was developed at Jönköping University in order to increase the strength of the material, but Esmaily’s research shows that the technique also gives the alloys the ability to withstand corrosion. Now that the connection has been mapped, new possibilities to optimise the microstructure for even better corrosion resistance have opened up.
Esmaily explained: “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.”