The effects of nickel in improving the mechanical properties and microstructural of Al-Zn-Mg-Cu alloys produced by semi-direct chill casting were investigated. Aluminium alloys were homogenized at different temperatures conditions, which aged at 120°C for 24 h (T6 temper), and retrogressed at 180°C for 30 min and then re-aged at 120°C for 24 h (RRA). The results of the microstructural analyses showed that with adding nickel to aluminium alloy, nickel-rich dispersoid particles were formed, such as Al7Cu4Ni, Al4Ni3, Al75Ni10Fe15, Al3Ni2, and Al50Mg48Ni7. Intermetallics compounds within the matrix alloy led to dispersion and fine-grain mechanisms which prevent the recrystallization and grain growth. Enhancement of mechanical properties of the alloys study is obtained through the precipitation hardening of alloying elements of the base alloy besides Ni-bearing dispersoid particles. The microstructure of these alloys were examined through optical and scanning electron microscopy along with energy dispersive X-ray and X-ray diffraction.
 N. Pourkia, M. Emamy, H. Farhangi and S. H. Syed Ebrahimi, “The Effect of Ti and Zr Elements and Cooling Rate on the Microstructure and Tensile Properties of a New Developed Super High-Strength Aluminum Alloy,” Materials Science and Engineering, Vol. 527, No. 20, 2010, pp. 5318-5325.
 D. K. N. Birbilis and P. A. Rometsch, “The Effect of PreAgeing Temperature and Retrogression Heating Rate on the Strength and Corrosion Behavior of AA7150,” Corrosion Science, Vol. 54, 2012, pp. 17-25.
 S. T. Lim, II S. Eun and S. W. Nam, “Control of Equilibrium Phases (M,T,S) in the Modified Aluminum Alloy 7175 for Thick Forging Applications,” Materials Transactions, Vol. 44, No. 1, 2003, pp. 181-187.
 A. K. Mukhopadhyay, “Microstructure and Properties of High Strength Aluminum Alloys,” Transactions of the Indian Institute of Metals, Vol. 62, No. 2, 2009, pp. 113-122. http://dx.doi.org/10.1007/s12666-009-0015-z
 B. C. Wei, C. Q. Chen and Y. G. Zhang, “Aging Behavior of Li Containing Al-Zn-Mg-Cu Alloys,” Materials Science and Engineering A, Vol. 280, No. 1, 2000, pp. 161-167. http://dx.doi.org/10.1016/S0921-5093(99)00684-X
 Y. Deng, Z. M. Yin, K. Zhao, J. Q. Duan, J. Hu and Z. B. He, “Effects of Sc and Zr Microalloying Additions and Aging Time at 120°C on the Corrosion Behaviour of an Al-Zn-Mg Alloy,” Corrosion Science, Vol. 65, 2012, pp. 288-298.
 D. N. Compton, L. A. Cornish and M. J. Witcomp, “The Effect of Microstructure on Hardness Measurements in the Aluminum-Rich Corner of the Al-Ni-Cr System,” Journal of Alloys and Compounds, Vol. 317-318, 2001, pp. 372-378.
 Y. Yang, K. L. Yu, Y. G. Li, D. G. Zhao and X. F. Liu, “Evolution of Nickel-Rich Phases in Al-Si-Cu-Ni-Mg Piston Alloys with Different Cu Additions,” Materials & Design, Vol. 33, 2012, pp. 220-225.
 U. Boyuk, S. Engin and N. Marasli, “Microstructural Characterization of Unidirectional Solidified Eutectic Al-SiNi Alloy,” Materials Characterization, Vol. 62, 2011, pp. 844-851. http://dx.doi.org/10.1016/j.matchar.2011.05.010
 N. A. Belov, D. G. Eskin and N. N. Avxentieva, “Constituent Phase Diagrams of the Al-Cu-Fe-Mg-Ni-Si System and Their Application to the Analysis of Aluminum Piston alloys,” Acta Materialia, Vol. 53, 2005, pp. 4709-4722. http://dx.doi.org/10.1016/j.actamat.2005.07.003
 Y. Yang, Y. Li, W. Wu, D. Zhao and X. Liu, “Effect of Existing Form of Alloying Elements on the Microhardness of Al-Si-Cu-Ni-Mg Piston Alloy,” Materials Science and Engineering: A, Vol. 528, No. 18, 2011, pp. 5723-5728. http://dx.doi.org/10.1016/j.msea.2011.04.022
 H. A. Ammar, C. Moreau, A. M. Samuel, F. H. Samuel and H. W. Doty, “Influences of Alloying Elements, Solution Treatment Time and Quenching Media on Quality Indices of 413-Type Al-Si Casting Alloys,” Materials Science and Engineering: A, Vol. 489, No. 1-2, 2008, pp. 426-438. http://dx.doi.org/10.1016/j.msea.2007.12.032
 J. Shen, R. Liu, Y. Liu, Z. Jiang and Q. Li, “Microstructures and Tensile Properties of Spray-Deposited HighStrength Aluminum Alloys,” Journal of Materials Science, Vol. 32, No. 3, 1997, pp. 829-832.
 W.-B. Li, Q.-L. Pan, Y.-P. Xiao, Y.-B. He and X.-Y. Liu, “Microstructure Evolution of Ultra-High Strength Al-ZnCu-Mg-Zr Alloy Containing Sc during Homogenization,” Transactions of Nonferrous Metals Society of China, Vol. 21, No. 10, 2011, pp. 2127-2133.
 G.-S. Peng, K.-H. Chen, S.-Y. Chen and H.-C. Fang, “Influnce of Dual Retrogression and Re-Aging Temper on Microstructure, Strength and Exfoliation Corrosion Behavior of Al-Zn-Mg-Cu Alloy,” Transactions of Nonferrous Metals Society of China, Vol. 22, No. 4, 2012, pp. 803-809.
 H. T. Naeem, K. S. Mohammed, K. R. Ahmad and A. Rahmat, “The Role of Direct Chilling, Retrogression and Reaging Treatment on Mechanical Properties of High Strength Aluminum Alloy,” Advance Materials Research, Vol. 795, 2013, pp. 211-218.
 O. P. Gbenebor, M. Abdulwahab and O. S. I. Fayomi, “Influnce of Inoculant Addition and Cooling Medium on the Mechanical Properties of Aa6063-Type Al-Mg-Si Alloy,” Chalcogenide Letters, Vol. 16, 2011.
 Z.-L. Li, J.-X. Xie, W. Chen, J. Zhai, H.-P. Ren and Y.-F. Wang, “Effects of Soild-Solution on Microstructure and Property of High Strength Spray Deposited Al-Zn-Mg-Cu Alloy Modified By Ni,” The Chinese Journal of Nonferrous Metals, Vol. 19, No. 12, 2009, pp. 2099-2105.
 L. Li, T.-T. Zhou, H.-X. Li, C.-Q. Chen, B.-Q. Xiong and L.-K. Shi, “Effect of Additional Elements on Aging Behavior of Al-Zn-Mg-Cu Alloys by Spray Forming,” Transactions of Nonferrous Metals Society of China, Vol. 16, No. 3, 2006, pp. 532-538.
 G.-F. Li, X.-M. Zhang, P.-H. Li and J.-H. You, “Effects of Retrogression Heating Rate on Microstructures and Mechanical Properties of Aluminum Alloy 7050,” Transactions of Nonferrous Metals Society of China, Vol. 20, No. 6, 2010, pp. 935-941.
 R. J. Flynn and J. S. Robinson, “The Application of Advances in Quench Factor Analysis Property Prediction to the Heat Treatment of 7010 Aluminum Alloy,” Journal of Materials Processing Technology, Vol. 153-154, 2004, pp. 674-680.
 W. H. Yuan, J. Zhang, C. C. Zhang and Z. H. Chen, “Processing of Ultra-High Strength SiCp/Al-Zn-Mg-Cu Composites,” Journal of Materials Processing Technology, Vol. 209, No. 7, 2009, pp. 3251-3255.
 M. M. Sharma, M. F. Amateua and T. J. Eden, “Hardening Mechanisms of Spray Formed Al-Zn-Mg-Cu Alloys with Scandium and Other Elemental Additions,” Journal of Alloys and Compounds, Vol. 416, No. 1-2, 2006, pp. 135-142. http://dx.doi.org/10.1016/j.jallcom.2005.08.045