Microstructure and mechanical characterization of cast Mg-Ca-Si alloys

• Published in: Journal of alloys and compounds Vol. 694; pp. 767 - 776
• Main Authors: Gil-Santos, Andrea, Szakacs, Gabor, Moelans, Nele, Hort, Norbert, Van der Biest, Omer
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 15.02.2017; Elsevier BV
• Subjects: Alloys; Compressive strength; Ductility; Intermetallic compounds; Intermetallic phases; Intermetallics; Magnesium base alloys; Magnesium compounds; Mechanical properties; Microstructure; Rapid-solidification; Semiconductors; Silicides; Solidification; Ternary systems; Intermetallics; Mechanical properties; Rapid-solidification; Microstructure
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2016.10.059

Three different phase fields are predicted and experimentally detected in the Mg rich corner of the Mg-Ca-Si ternary diagram. The present phases are Mg + MgCaSi + Mg2Si in phase field 1, Mg + MgCaSi in phase field 2 and Mg + Mg2Ca + MgCaSi in phase field 3. The focus of this study is on the formation and evolution of the intermetallic phases. The final microstructures have been related with their solidification process and with the alloys mechanical properties. A clear influence of the observed intermetallic phases on the mechanical performance was found. A bigger size and higher amounts of the MgCaSi intermetallic phase increase the alloys strength and make them brittle, while in its fine morphology MgCaSi reduces the strengthening effect and slightly decreases the ductility compared to pure Mg. Mg2Si phase in its needle-like small size morphology contributes to an increase of the hardness and compressive strength. Its presence reduces the alloys ductility making them brittle. Finally, the highest values for compressive strength and hardness are related to the Mg2Ca presence. •Mg2Si, MgCaSi and Mg2Ca are found to be present in Mg rich corner alloys.•The intermetallics of Mg rich alloys in Mg-Ca-Si system depend on the Ca/Si ratio.•The intermetallic phases influences mechanical performance.•Fast-solidification predictions of the Mg-Ca-Si alloys is verified.