By changing the microstructure in magnesium alloys,
Mohsen Esmaily, researcher in Atmospheric Corrosion at Chalmers University of
Technology (Gothenburg, Sweden), has succeeded in improving possibilities for
the transport sector to use these materials to decrease the weight of vehicles.
Magnesium is the lightest construction metal, but also
the most reactive. This means that it is very sensitive to corrosion, i.e. it
very easily reacts with its surroundings and rusts. This makes it difficult to
use magnesium in corrosive environments, which means that the potential to use
magnesium in cars to make them lighter is limited.
For more than a hundred years, magnesium producers have
worked hard to improve the corrosion characteristics by developing new, more
corrosion- resistant alloys, and also by developing various coatings. Mohsen
Esmaily's research shows a completely new way to improve the corrosion
resistance of the alloys by manipulating the microstructure of the material,
thereby increasing possibilities to lower the weight of vehicles.
"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, aluminum, would mean a great step forward to
reduce fuel consumption," says Mohsen Esmaily.
It was when he studied magnesium casts produced through a
casting method called rheocasting that he 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. This new knowledge is based on a combination of unique exposure
methods and a number of advanced analytical methods.
Rheocasting of magnesium alloys was developed at
Jönköping University in order to increase the strength of the material, but
Mohsen Esmaily's research shows that the technique also gives the alloys
surprisingly good ability to withstand corrosion. With his research he shows
the connection between the microstructure of the alloy and its corrosion
resistance. Now that the connection has been mapped, new possibilities to
optimize the microstructure for even better corrosion resistance have opened
up.
"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," Mohsen Esmaily says.
Over the past three years he has published over 30 articles, 22 of which
as the main author. In these Mohsen Esmaily reports results that may increase
the use of magnesium alloys and aluminum alloys in vehicles. Several of the
articles have had a great impact in the field. One was the most downloaded
article from the journal Corrosion
Science in 2015. He has also been recognized by the Royal Swedish
Academy of Engineering Sciences, which gave him SEK 50,000 for his work on
magnesium corrosion.
Source: Chalmers University of Technology, chalmers.se/en