Increasing the strength of aluminum



In their efforts to make lighter vehicles and thereby reduce gas consumption and greenhouse gas emissions, car manufacturers are increasingly turning to aluminum alloys to replace steel. In addition to being resistant to corrosion and wear and absorbing shocks, aluminum can reduce a vehicle's weight by 30% to 40%. However, this metal has a dark side. At temperatures above 200˚C, it loses strength which, in the long run, leads to premature breakage. This is what happens in diesel engines, where highly compressed air causes temperatures to oscillate between 250˚C and 1,000˚C.

At temperatures above 200˚C, aluminum loses strength.

Mihriban Pekguleryuz, a materials engineering professor at McGill University, in collaboration with Grant Chen from UQAC and Philippe Bocher from ETS, is attempting to correct this problem by using nanoparticles to reinforce the microstructure of the aluminum-silicon-magnesium-copper alloys currently used by the automobile industry.

For several years the researchers have been experimenting in the laboratory with different mixtures, which they then subject to mechanical testing. During testing, microparticles of manganese and molybdenum, two metals known for their hardness, have shown the best results. Incorporated into aluminum alloys, they improve the ability of components to deform without breaking. Used for the first time in an alloy, molybdenum combined with manganese greatly improves the mechanical properties of diesel engines at temperatures above 300˚C.

While the recipe developed by Professor Pekguleryuz and her team still requires some work before reaching the commercialization stage, it is already being used by other laboratories to improve the conductivity of pure aluminum alloys and the mechanical properties of aluminum alloys in foundries.