Simultaneous modification and grain refinement of the aluminum-silicon-copper alloy using a Magnesium Matrix Alumina Composite as the Master Alloy

Date of Award


Degree Type



Mechanical, Automotive, and Materials Engineering




The main properties that make aluminum alloys a valuable material are their light weight, strength, corrosion resistance, durability, ductility, formability and thermal conductivity. Due to these unique combinations of properties, the variety of applications for aluminum continues to increase. In addition, to increase the reliability of cast aluminum components the microstructure must be modified and refined. The castings being modified by currently used master alloy have many problems (segregation, porosity). This thesis was designed to investigated the Magnesium Matrix Alumina Composite (MMAC) Master Alloy would be able to solve some of these problems. The MMAC Master Alloy contains nano Alumina particles and Magnesium which have the unique abilities to simultaneously refine and modify the microstructure of the cast aluminum structure. The experimental work performed showed that the MMAC Master Alloy reduces the Secondary Dendrite Arm Spacing and improves the Silicon Modification Level, Porosity Area Fraction and Mechanical Properties of the casting.