Affiliation: | aEnvironmental Corrosion Center, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016, People's Republic of China bInstitut National Polytechnique de Grenoble (INPG), Science et Ingénierie des Matériaux et Procédés (SIMAP), CNRS UMR 5266, UJF, GPM2, BP 46, 38402 Saint-Martin d’Hères Cedex, France cGraduate School of the Chinese Academy of Sciences, People's Republic of China |
Abstract: | Mg–Al–Ca alloys are creep resistant magnesium alloys with high application potentials. The solidification pathways and microstructure formation in this alloy system are still under discussion. In this paper, the solidification behavior of AZ91 and AM50 with Ca addition (AZC91x and AMC50x alloys) was investigated by a computer-aided cooling curve analysis (CA-CCA) system. Microstructure and phase identification were carried out by SEM and EDX analysis. The results show that the Ca-containing phase formation mainly depends on Ca content and Ca/Al ratio. With increasing the Ca/Al ratio these phases transform from Al2Ca to (Mg, Al)2Ca and Mg2Ca. Moreover, Ca addition decreases the liquidus temperature of Mg–Al alloys, but influences the solidus temperature in a more complex way. Increasing the Ca content also decreases the solid fraction at which dendrite coherency occurs. The relationship between solidification interval, dendrite coherency point, formation of Ca-containing phases and hot tearing is also discussed. |