| The study of magnesium matrix composite is one of the most interesting research topices at the air and automobile industry due to their high special strength and wear resistance properties. However, the difficulties for the common ways to fabricate these composites such as reinforcement dispersion problem and undesired interface reaction in casting technology or the complex process and high costs of the traditional PM technology limit the use of magnesium composites. SiCp reinforced Mg-9A1 alloy composites with high mechanical properties were fabricated successfully by powder extrusion technology. Powder extrusion technology enables us to design and fabricate magnesium composites conveniently, and has relatively simple and safe technics suitable for mass production of particulate reinforced magnesium matrix composites.In this thesis, the effects of alloying time, volume fraction and morphology of SiCp, hot extrusion process parameters on the microstructures and mechanical properties of composites were studied, and the best fabrication parameters were gained, and study on the Mg-9A1 for diffusion alloying mechanicsm.Research showed that one of the key points for SiCp reinforced magnesium matrix composites using Powder retrusion was the degree of alloying which was achieved by sintering. Volume fraction and size of SiCp and hot extrusion parameters to the microstructures, tensile fracture surface and mechanical properties of the composites were studied by means of OM, SEM, and XRD, the best parameters were obtained as followa:at 380℃for diffusion alloying 3h, thel5vol.%SiCp/Mg-9Al composite fabricated using those parameters has well distribution of SiCp and good interface between SiCp and matrix, its yield and tensile strength were 257MPa,279MPa respectively, and they were increased to 302MPa,315MPa respectively through solution and aging treatment. |
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