Magnesium alloys have found increased application in the automotive industry because of their lower densities compared to steels and aluminum alloys, and their higher temperature capabilities and improved crash worthiness compared to polymers. Their application can be increased if their mechanical properties can be improved further. Grain Refining is one of the effective methods for improving the comprehensive mechanical properties of metals and alloys. However, existing grain refining technologies for Mg alloys are either too expensive or not capable for grain refining of castings using low pressure permanent mold casting process. This thesis reports a method using nano-particles for grain refining. Ultrasonic vibration is used for dispersing SiC nano-particles into molten metal in order to use these particles as nuclei for grain refinement. Experimental results indicate that nano-particles that are dispersed into molten metal using ultrasonic vibration can serve as nuclei for reducing grain size significantly in Mg alloys.
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