Aluminium-based composite materials are frequently preferred in many new-generation engineering applications due to their high strength, wear and corrosion resistance, improvement of mechanical properties, machinability, and low density. Mechanical alloying is essential in producing composites with high properties in powder metallurgy, which is one of the composite material production methods. In this study, the deformation of AA7075 powder was investigated with a three-dimensional ball mill designed and produced for use in mechanical alloying processes. In the milling processes, three different rotational speeds (150, 200 and 250 rpm), three different ball to powder ratios (5:1, 10:1 and 20:1) and three different milling times (30, 60 and 90 min) were used. The particle deformation was evaluated by particle size analysis and powder structure examination. The obtained results were analysed with analysis of variance, regression method, three-dimensional graphics, optical microscope and scanning electron microscope (SEM) images. When the results were examined, the maximum deformation and powder size among the selected experimental parameters were obtained at 150 rpm rotational speed, 20:1 ball to powder ratio, and 90 min.