Ternary Al-4.5 (wt%) Cu-3.4 (wt%) Fe in-situ composite was prepared at 1100˚C by conventional casting method. However, this particular alloy contains larger needle-shaped intermetallics of Al 3 Fe phase. These exert adverse effect on the mechanical properties of the alloys. The larger shape and uneven orientation of the intermetallic were found to be responsible for the degradation of properties. The main purpose of this study was to modify the geometry of those needles by adding magnesium (Mg) as a fourth material. A series of alloys were prepared by adding 4, 6, 8, 10, wt% Mg in Al-4.5 (wt%) Cu-3.4 (wt%) Fe alloy. Microstructures were observed by optical microscopy. Mechanical properties like ultimate tensile strength, % elongation, % area reduction, hardness and wear test were determined. The study revealed that Mg transformed the needles of Al 3 Fe into globular shape which gave the alloys better mechanical properties.