How can corrosion of magnesium alloys be prevented?

Collaboration of the Siberian Branch of the Russian Academy of Sciences (SB RAS), including both Tomsk Scientific Center (TSC) and Institute of High Current Electronics (IHCE), with Milan Polytechnic University (Italy) continues. Scientists from two countries have proposed optimal methods for electron-beam processing of magnesium alloys, which enable to improve their corrosion resistance by several times. One of the results of this international cooperation is the ‘Surface properties modification alloys by low energy high current pulsed electron-beam’ paper in the ‘Surface and Coatings Technology’ journal (Q1 according to the Web of Science database).

Magnesium alloys are widely demanded in the aerospace and automotive industries due to their low weight that enables to enhance the efficiency of manufactured vehicles and reduce the negative impact on environment. However, there are some challenges associated with their low wear and corrosion resistance.

‘Magnesium alloys include several grades, typically containing of 90% Mg with 6–8% Al and only a few percent of other chemical elements. Their microstructures are heterogeneous with intermetallic phases in the surface layers that are initial points of corrosion processes under any severe conditions. As a result, bulk metal may be deteriorated totally,’ said, Evgeny Yakovlev, research fellow of the Laboratory of Advanced technologies of the TSC SB RAS. ‘Therefore, one of the urgent tasks, facing materials scientists from all over the world, is to prevent these corrosion processes,’ he added.

A group of scientists from both countries has carried out electron-beam processing of magnesium alloys of several grades using a wide range of irradiation modes (more than twenty for each one). The scientists have observed and described the optimal parameters that have caused dissolution of intermetallic phases and enrichment of the surface layers with aluminum. Respectively, both strength and corrosion resistance have been improved.

Evgeny Yakovlev explained how this effect is achieved: ‘Due to electron-beam processing, the surface layer melts. In the liquid phase, dissolution of intermetallic compounds occurs. As a result, corrosion resistance of magnesium alloys increases by several times”.

‘The COVID-19 pandemic is not an obstacle to our collaboration. We hope that the proposed procedures will be widely used by other Italian universities and enterprises. I believe that these joint research activities facilitate and accelerate the implementation progress of the scientific results,’ said Massimiliano Besttetti, professor at Milan Polytechnic University, highly appreciating the results obtained by the international team. According to Massimiliano Besttetti, many Italian colleagues will continue to actively cooperate with the Siberian scientists to expand the electron-beam processing possibilities to other materials such as magnesium, aluminum and titanium alloys.

Under the auspices of the TSC SB RAS, a collaboration memorandum was signed between the IHCE SB RAS and Milan Polytechnic University four years ago. Within its framework, a group of scientists from both IHCE and TSC SB RAS developed and delivered high-tech electron-beam equipment to the Italian colleagues. Nowadays, it is the foundation of the Science and Technology Park, on the basis of which research is carried out by them.