![]() Materials and MethodsĪs the basic materials for this research, Mg alloy (AZ91) and Al alloy (6061) were used. The pressure supplying device based on thermal expansion is considered the first time applied to the diffusion welding of Mg/Al alloys, which makes the welding process much simpler than the traditional diffusion bonding process, as no additional pressure is required during the welding process. In addition, microstructure and bonding properties of the diffusion layers were investigated. To improve the microstructure and mechanical behaviors of Mg/Al composite, annealing was carried out. In this research, the diffusion bonding method was selected furthermore, pressure supplying device based on thermal expansion was particularly applied. ![]() Therefore, solid-state bonding technologies, such as diffusion welding, friction stir welding, and ultrasonic welding, have been widely used for controlling the formation of IMC. Because solid-state welding can occur at lower temperatures in relative to fusion welding, there is no mass transfer between liquid and solid phases, suggesting that the formation of IMC is reduced. Besides, the intermetallic compounds (IMCs) in the interface are brittle and hard, which may seriously deteriorate the properties of the joints. However, due to the different properties of magnesium alloy and aluminum alloy, especially thermodynamic properties, it is difficult to weld them together. ![]() In order to combine their advantages, the welding of Mg alloys to Al alloys has become more and more significant, especially for transportation machinery manufacturing industry such as automobile manufacturing field, aviation machinery manufacturing field, and so on.įew research studies have focused on the diffusion bonding of Mg and Al alloys by various dissimilar material joining techniques, such as fusion welding, rolling, brazing, friction stir bonding, and vacuum diffusion bonding. As lightweight materials, magnesium alloys (Mg alloys) and aluminum alloys (Al alloys) have been widely used in many fields, such as automotive, electronics, and aerospace industries, due to their excellent performance of high specific strength, low density, and good formability. Lightweight is an effective way to meet the requirements of energy conservation, sustainable development, and environmental protection. In the wake of industry development and economy growth, energy and environmental problems are becoming more and more serious. In addition, the thermal expansion pressure supplying process was appropriate for the diffusion bonding of Mg/Al alloys. Therefore, 250☌ was determined to be the most suitable annealing temperature. A possible reason for this could be that 250☌ is nearly similar to the recrystallization temperature of Mg/Al alloys. Intermetallic compounds in the diffusion zone were identified as Al 2Mg and Al 12Mg 17, the microstructure and elemental composition were uniformly distributed, and tensile strength was the largest for the specimen annealed at 250☌. The results showed that the diffusion zone widens with increasing annealing temperatures, but it changed obviously when the annealing temperature was 300☌. Furthermore, tensile strength and hardness values were also measured. For further assessment of the diffusion zone, microstructural examination was carried out using a transmission electron microscope. Elemental analysis and structural observation/compound identification were conducted using an electron probe microanalyzer and a scanning electron microscope, respectively. To enhance the microstructure and bonding properties of the welded Mg/Al alloys, the annealing process was continuously implemented on the composite specimens. 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).
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