Influence of aging process and reinforcement ratio on physical and mechanical properties of carbonized aramid reinforced Al7075 materials

Abstract

The high mechanical properties, corrosion resistance and low production costs of aluminum alloys make their use in the aerospace and automobile industries attractive. Addition of reinforcement, and heat treatment are important factors in increasing the physical and mechanical properties of these alloys. In this study, squeeze casting method was used to produce aramid reinforced Al7075 matrix materials and their mechanical, physical and microstructural properties were investigated. The physical (hardness) and mechanical (tensile, flexural) properties of Aramid/Al7075 material were compared with base alloy. Then, the effects of the aging process on the hardness, tensile and flexural strengths of 8%Aramid/Al7075 material (the best mechanical properties) and base alloy were investigated. The polished surfaces of the materials and the fracture surfaces after the tensile test were examined using Scanning Electron Microscopy (SEM), while the phase characterization after aging was performed using X-ray diffraction (XRD). The highest hardness values of non-aged materials were obtained in 12% aramid reinforced material. The highest flexural and tensile stress were obtained from 8% aramid reinforced material among non-aged materials, and their strengths were determined as 454 and 278 MPa, respectively. With an increase in aging time, the mechanical and physical properties of the materials exhibited a significant improvement. However, it was observed that these properties started to decrease after a certain aging time. In heat-treated Aramid/Al7075 materials, the lowest and highest hardness values were obtained as 184 and 205 HB, respectively, after aging for 8 and 20 h. The highest tensile strength (523 MPa) of the Al7075 alloy was obtained at the end of 20 h. The highest tensile strength of aramid reinforced material was obtained as 512 MPa at 16 h aging time.