Evaluation of microstructure and mechanical properties of squeeze overcast Al7075−Cu composite joints

Abstract

Al7075−Cu composite joints were prepared by the squeeze overcast process. The effects of melt temperature, die temperature, and squeeze pressure on hardness and ultimate tensile strength (UTS) of squeeze overcast Al7075−Cu composite joints were studied. The experimental results depict that squeeze pressure is the most significant process parameter affecting the hardness and UTS. The optimal values of UTS (48 MPa) and hardness (76 HRB) are achieved at a melt temperature of 800 °C, a die temperature of 250 °C, and a squeeze pressure of 90 MPa. Scanning electron microscopy (SEM) shows that fractured surfaces show flat-faced morphology at the optimal experimental condition. Energy-dispersive spectroscopy (EDS) analysis depicts that the atomic weight percentage of Zn decreases with an increase in melt temperature and squeeze pressure. The optimal mechanical properties of the Al7075−Cu overcast joint were achieved at the Al2Cu eutectic phase due to the large number of copper atoms that dispersed into the aluminum melt during the solidification process and the formation of strong intermetallic bonds. Gray relational analysis integrated with the Taguchi method was used to develop an optimal set of control variables for multi-response parametric optimization. Confirmatory tests were performed to validate the effectiveness of the employed technique. The manufacturing of squeeze overcast Al7075−Cu composite joints at optimal process parameters delivers a great indication to acknowledge a new method for foundry practitioners to manufacture materials with superior mechanical properties.