Transient Liquid Phase Bonding of Magnesium Alloy AZ31 Using Cu Coatings and Cu Coatings with Sn Interlayers

Abstract

Transient liquid phase bonding (TLP) of AZ31 samples has been investigated using Cu coatings and Cu coatings with Sn interlayer. Copper coatings were used for one set of the bonds, and a combination of Cu coatings and Sn interlayer was used for the other set of bonds. The bonding temperature was fixed at 520 • C, and various bonding times were applied. This study shows that the bonds produced using only Cu coatings have shown weaker bonds compared to the bonds made using Cu coatings and Sn interlayer. The Cu 2 Mg particles were detected at the joint region of both bonds made by Cu coatings and Cu coatings with Sn interlayer by X-ray diffraction (XRD). However, it has been observed that the joint region was dominated by solid solution which is rich in Mg. Sn interlayer was not contributed to the intermetallic compound (IMC) at the joint region, and therefore it was diffused away through the Mg matrix. Within the joint interface, a slight increase of micro-hardness was observed compared to Mg base metal alloy. This was attributed to the formation and presence of IMC's within the joint region. It was noticed that the presence of the Sn interlayer improved the joint strength by reducing the pores at the joint region. Pores were clearly observed for those bonds made using Cu coatings-especially for region where the fracture occurs; this was accomplished by scanning electron microscope (SEM).

Dissimilar Welding and Joining of Magnesium Alloys: Principles and Application

“…The scientific literature shows that suitable interlayers must allow eutectic melting while limiting the volume of the liquid that forms in order to control the width of the interface and shorten the homogenization stage of bonding [3]. Additionally, the wettability of the base metals by the molten interlayer is critical to displacing surface oxides in order to form a joint [2]. When suitable interlayers are used, the formation of intermetallic compounds (IMC) can be prevented or significantly reduced.…”

“…The utilization of magnesium alloys has seen an increase at the rate of 15% and is predicted to go even higher over the next decade. Currently, magnesium is used widely as a structural material due to low density and favorable damping characteristics, low casting costs and machinability [2]. However, new magnesium alloys are being developed with enhanced corrosion resistance and enable these materials to operate satisfactorily inside the human body.…”

“…Electron probe micro-analysis (EPMA) micrographs of Mg, Cu, and Sn for bonds made using Cu coating and Sn-foil interlayer at 20 minutes[2].…”

Diffusion Bonding and Brazing of Advanced Materials

“…However, the used interlayers have to be well selected in order to promote a quality bonding of these lightweight alloys. AlHazza et al [5] investigated the use of Cu coatings and Cu coatings with Sn interlayer in the TLP bonding of an AZ31 alloy. The presence of the Sn interlayer promotes an improvement in the joint strength, revealing an excellent approach to apply in the implementation of this joining process.…”

Microstructures, Tensile Properties and Creep Characteristics of as-Extruded AZ91 Magnesium Alloy Containing Si, Ca and Rare Earth Elements

“…Magnesium alloys are new light-weight metal structural materials [1][2][3][4]. Mg-Al-Zn (AZ series) alloys are among the most popular magnesium alloys and widely used for commercial applications, owing to their low cost, excellent room temperature strength, good die castability and favorable corrosion resistance [5].…”