The development of inter-metalic compound Mg2Si reinforced AZ91/Mg2Si compositive material

ivTHE DEVELOPMENT OF INTER-METALIC COMPOUND Mg2SiREINFORCED AZ91/Mg2Si COMPOSITE MATERIAL(M.Sc. Thesis)Ayhan DEMIRGAZI UNIVERSITYINSTUTE OF SCIENCE AND TECHNOLOGYJanuary 2006ABSTRACTIn this study, effect of calcium and different production conditions onmodification of Mg2Si in AZ91/Mg2Si in-situ magnesium composite wasinvestigated. Fine and polygonal Mg2Si having low density, high hardness andelastic modulus improves mechanical properties of the composites. Thereforethe morphology of Mg2Si has been changed from the Chinese script to smallpoliygonal shape through addition of calcium and/or controlling thesolidification behaivour. In-situ AZ91/Mg2Si composite was produced by meltstirring method. After preparation of the alloy, calcium and then silicon wereintroduced into the melt at 670 ºC and then cast into a special die at 720 ºC.Some of the specimens were produced in different production conditions tomodifiy the microstructure and Mg2Si. Specimens for optical microscopy andscanning electron microscopy (SEM) were etched with a solution of 2 vol. %nitric acid + ethyl alcohol. Furthermore tensile testing bars and hardnessspecimens were prepared for mechanical tests. As a result, Mg2Si was changedto relatively polygonal type, and thus mechanical properties of composite wasimproved.Sicence Code : 710Key Words : In-situ, Mg2Si, Composite, Microstructure andMechanical PropertiesPage number : 90Adviser : Prof.Dr.Burhanettin INEM