Development of the first bake hardenable magnesium sheet alloy that can be formed at room temperature.
2018.08.05
A collaborative research team of NIMS, Nagaoka University of Technology and Sumitomo Electric Co. Ltd. have developed the first bake hardenable magnesium sheet alloy that can be formed at room temperature, thereafter can be strengthened by age harding during the paint baking process of automotive production line. The results have been published in a paper entitled "Bake-hardenable Mg–Al–Zn–Mn–Ca sheet alloy processed by twin-roll casting" by M. Z. Bian et al. in Acta Materialia, Volume 158, Pages 278-288 as an open access paper. Everyone can download the paper from the following link:
The bake hardenable (BH) magnesium alloy contains only small amounts of ubiquitus elements such as Al, Zn, Mn and Ca, so the materials cost is as low as medium strength aluminum alloys. Since it is manly composted of Mg, it is lighter than aluminum sheet alloys and its specific strength is higher. Because of an apporopriate choice of Al:Zn:Ca ratio, atomic clusters called Guinier Preston zones are formed during baking the alloy at 170C for 20 min, which strengthen the sheet after forming to the final shape. The team also carried out detailed atomistic characterization of the alloy during the bake hardening process, and they attributed the solute segregation to dislocations cause unique yield phenomenon observed in this alloy, which is unusual for magnesium alloys.