Science and Education Publishing American Journal of Materials Science and Engineering 2333-4673 2 4 2014 10 13 Effect of Variation in Magnesium and Copper on Mechanical Properties of X7475 Aluminium Alloy 54 61 EN L.T. Tuleun J.D. Amine K. Abubakar Department of Research, Collaboration and Consultancy, National Centre for Technology Management (NACETEM), Abuja, Nigeria AJMSE2014242 10.12691/ajmse-2-4-2 2014 09 12 2014 09 30 2014 10 13 Aluminium (Al) alloys are employed, from aerospace, automotive body panel, building industry to kitchen wares. This paper attempts to close an existing gap in the usage and variation in the percentage weight (% w.t.) of two constituents [Magnesium (Mg) and Copper (Cu)] in Al alloy and evaluate the impact of such variations on yield strength in N/mm2 and percentage elongation (% e) at ambient temperature. Experimental X7475 alloy was prepared from constituents drawn from 6 % Zn, 2.5 % - 3.5 % Mg, 1.8 % - 3.0 % Cu, 0.03 % Mn, 0.23 % Cr and Al as balance in all cases. The result revealed that yield strength increased with increase in Mg and decreased with increase in Cu as a maximum yield strength of 384.57 N/mm2 was displayed by an alloy of 2.5 % Mg, 3.0 % Cu while the least yield strength of 130.00 N/mm2 was recorded by an alloy of 3.5 % Mg, 3.0 % Cu. Ductility (% e) increased with increase in Cu. The paper submitted that mechanical properties of Al alloys depend not only on the content of alloying elements, but also on their relative chemistries with each other, impact of impurities and heat treatments.