This study used a vacuum diffusion welding process to weld magnesium (Mg1) and aluminum (Al1060). The diffusion layers, with different phase compositions, were separated and extracted by grinding. The diffusion layers’ microstructures and phase compositions were analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Furthermore, the corrosion resistance of each diffusion layer and the substrates were investigated and compared by performing corrosion immersion tests and linear polarization measurements in a 3.5 wt.% NaCl solution. The results showed that diffusion layers consisting of Mg₂Al₃, Mg₁₇Al₁₂, and Mg₁₇Al₁₂/Mg-based solid solutions were formed at the interface of the Mg1/Al1060 vacuum diffusion joint. Furthermore, each diffusion layer’s structure and morphology were of good quality, and the surfaces were free from defects. This result was obtained for a welding temperature of 440 °C and a holding time of 180 min. The corrosion current density of Mg1 was 2.199 × 10⁻³ A/cm², while that of the Al1060, Mg₂Al₃, Mg₁₇Al_12, and Mg₁₇Al₁₂/Mg-based solid solutions increased by order of magnitude, reaching 1.483 × 10⁻⁴ A/cm², 1.419 × 10⁻⁴ A/cm², 1.346 × 10⁻⁴ A/cm^2, and 3.320 × 10⁻⁴ A/cm², respectively. The order of corrosion rate was Mg1 > Mg₁₇Al₁₂ and Mg-based solid solution > Mg₂Al₃ > Mg₁₇Al₁₂ > Al1060. Moreover, all diffusion layers exhibited an improved corrosion resistance compared to Mg1. This was especially the situation for the Mg₂Al₃ layer and Mg₁₇Al₁₂ layer, whose corrosion resistances were comparable to that of Al1060.

In this study, pressure supplying device based on thermal expansion and vacuum diffusion bonding method were used to weld magnesium alloy (AZ91) and aluminum alloy (6061). To enhance the microstructure and bonding properties of the welded Mg/Al alloys, the annealing process was continuously implemented on the composite specimens. Elemental analysis and structural observation/compound identification were conducted using an electron probe microanalyzer and a scanning electron microscope, respectively. For further assessment of the diffusion zone, microstructural examination was carried out using a transmission electron microscope. Furthermore, tensile strength and hardness values were also measured. The results showed that the diffusion zone widens with increasing annealing temperatures, but it changed obviously when the annealing temperature was 300°C. Intermetallic compounds in the diffusion zone were identified as Al₂Mg and Al₁₂Mg₁₇, the microstructure and elemental composition were uniformly distributed, and tensile strength was the largest for the specimen annealed at 250°C. A possible reason for this could be that 250°C is nearly similar to the recrystallization temperature of Mg/Al alloys. Therefore, 250°C was determined to be the most suitable annealing temperature. In addition, the thermal expansion pressure supplying process was appropriate for the diffusion bonding of Mg/Al alloys.

In this study, magnesium alloy AZ31 was successfully welded with aluminum alloy 6061 by diffusion bonding method. In addition, annealing process was applied to refine micro-structure and improve mechanical property. Microstructure and elemental distribution of interface were investigated with Scanning Electron Microscope (SEM) and Electron Probe Micro Analyzer (EPMA). Furthermore, experiments on diffusion bonded specimens with the usage of Transmission Electron Microscope (TEM) were carried out. At last, tensile strength was measured. It can be obtained that the width of diffusion layers increase with the increasing annealing temperatures. Elemental distribution of specimens with annealing were more uniform than that without annealing. The intermetallic compounds in diffusion layers are Al₃Mg₂ and Al₁₂Mg_17, their crystal structure are respectively face-centered cubic (fcc) and body-centered cubic (bcc). What’s more, tensile strength turns to be strongest after annealing at 250°C.