Effects of Al and Ca on microstructure and surface defect of
magnesium alloy thin strip
magnesium alloy thin strip
(1. National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400030, China;
2. College of Materials Science and Engineering, Chongqing University, Chongqing 400030, China)
2. College of Materials Science and Engineering, Chongqing University, Chongqing 400030, China)
Abstract: Mg-Al-Zn alloy thin strips were prepared by vertical twin-roll casting. Effects of Al and Ca on the microstructure and the surface defects of the thin strips were investigated. The results show that with the increase of Al content, the quantity of surface cracks of the thin strips increases rapidly and their locations are moved to the center of the thin strips. The alloy melts with more than 0.10% Ca (mass fraction) stick on the roller and a poor surface quality of the thin strips appears. With the increase of Al content, the microstructure of the thin strips evolves from single α-Mg phase, characterized by the uniform and equiaxed recrystallization grains, to the combination of dendritic α-Mg with Al supersaturated α-Mg. The minor addition of Ca can obviously refine the grains of Mg-3Al-1Zn thin strip because the formation of Al2Ca and the finest grains are obtained by adding 0.08% Ca.
Key words: magnesium alloy; twin-roll casting; thin strip; grain refinement