Volume 9 Issue 2 ( June 2022 )

Aluminum alloy AA 7075 majorly consists of Zinc and Magnesium, and it has been known as an alloy with high strength and ability to be heat treated. In regard to that, AA 7075 alloy was investigated to determine its application in military vehicles that require high protection and great mobility capabilities. The addition of Al₂O₃ can be done to improve the mechanical properties of the material such as hardness and impact toughness that is related to the protective ability of the material. This research was conducted to determine the effect of adding nano Al2O3 and heat treatment on the ballistic resistance of composite plates. The composites were fabricated by the squeeze casting method followed by heat treatment of T6 at 470 °C for two hours, water quench, and artificial aging at 120 °C for one hour. The reinforcement of nano Al₂O₃ is added to the melted aluminum alloy when the fabrication process takes place as much as 0.1, 0.2, 0.3 wt%. Furthermore, the composite plate was tested by ballistic testing Type II and III according to NIJ standard. Other characterizations were also carried out on the samples such as microstructural observations and hardness testing. The results of the characterization have found that all samples have protective ability in Type II ballistic testing but do not have protective ability in Type III ballistic testing. The addition of reinforcing particles affects the value of the hardness of composite material. Heat treatment increases the hardness value, impacts toughness value, and penetration trace in ballistic testing which has a direct relationship to microstructural changes that occur during the heat treatment process.

Keywords: aluminum composite, AA 7075, Al₂O₃ reinforcement, ballistics, heat treatment, aging