Evaluation of Microstructure and Mechanical Properties in Dissimilar Joint of SSM7075 with SSM356 Aluminum Alloy using Diffusion Bonding

The aim of this study is to investigate joining parameters that affect microstructure and mechanical properties of diffusion bonding technique in dissimilar joints between SSM7075 and SSM356 aluminum alloys. Diffusion bonding methods were investigated by joining parameters as follows: contact pressure at 3 MPa, holding time 60 and 120 minutes and temperature at 673, 723, 773 and 823 K respectively, under argon atmosphere at 4 litres per minute. After experiments, the results of the investigation have shown that a condition used contact pressure at 3 MPa, holding time 120 minutes, and temperature at 773 K is complete and no defects and voids. Examination of the joint region using SEM and EDX showed that the microstructure in weld zone after welding is globular structure, and eutectics phases of two materials diffuse together. In weld zone, it was found that formation of eutectic phases has Al2CuMg, Mg2Si and Al2Mg2Zn3 phases along the bond interface, distributed throughout bond interface. The tensile tested showed the maximum tensile strength of 94.94 MPa. The hardness was tested for optimum hardness value, 121.20 HV. However, the heat during welding, resulting in precipitation within the aluminum matrix (α-Al), led to increased hardness after diffusion bonding

Transient Liquid Phase Bonding of Semi-Solid Metal 7075 Aluminum Alloy using ZA27 Zinc Alloy Interlayer

Transient Liquid Phase Bonding (TLPB) process of semi-solid metal 7075 aluminum alloys (SSM7075) using 50 μm thick of ZA27 zinc alloys as interlayers for the experiment were carried out under bonding temperatures of 480 and 540 °C and bonding times of 30, 60, 90 and 120 min respectively. In the bonding zone, the semi-solid state of ZA27 zinc alloy interlayers were diffused into the SSM7075 aluminum alloy. Examination of the bonding zone using Scanning Electron Microscope (SEM) and Energy-dispersive X-ray spectroscopy (EDS) showed that the precipitation of the intermetallic compound of η(Zn–Al–Cu), β(Al2Mg3Zn3), T′(Zn10Al35Cu55) and MgZn2 were formed in the bonding zone. The better homogenized microstructure in the bonding zone was formed when increasing bonding time and bonding temperature. The highest bonding strength was recorded at 17.44 MPa and average hardness was at 87.67 HV with the bonding time of 120 min and temperature at 540 °C. Statistically, the coefficient of determination analysis of bonding strength data was at 99.1%