Study On Liquid Phase Diffusion Bonding Process Of ZK60 For Magnesium Alloy

Magnesium alloy has been used as a reliable structural material in modern times for its advantages, such as low density, good machinability, high strength, good damping properties and good thermal conductivity, good vibration reduction and so on. ZK60 magnesium alloy acts as the representative of higher strength among many magnesium alloy, it is an obstacle how to put it into practical application, which is a problem about its poor welding performance. In order to make it can be more extensive used in the industry area, it is badly need of researching a suitable welding method, as a result, the research of ZK60 magnesium alloy welding process is extremely important.This paper briefly analyzes the mechanism of transient liquid phase (TLP) diffusion bonding process, the influences of interlayer material and thickness, bonding temperature, bonding pressure, holding time and other parameters in the process are discussed. The fracture morphology, phase composition and the diffusion, metallurgical structure, chemical composition, phase composition of the joint region are analyzed with optical microscope, universal tensile testing machine, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction analysis device, finally, the effects of various process parameters on the joint properties are determined, the necessary theoretical support and experimental basis for the transient liquid phase (TLP) diffusion bonding of magnesium alloy ZK60 are provided.In this paper, the transient liquid phase diffusion bonding of magnesium alloy ZK60 is studied, pure aluminum and zinc foil are used as interlayer, the optimal experimental parameters, which are required for getting a good joint are determined through tests. The results are as follows:1. Aluminum foil is used as the interlayer, under the parameters condition of 0.5MPa bonding pressure,480℃ bonding temperature and 1 hour holding time, shear strength of the joint can be up to 155MPa, which can also reach 89.6% of the base material strength, during the connection process, the diffusion rate is increasing while the connection temperature improving; diffusion can become more thorough with the improvement of thermal time; microscopic surface can become more closely integrated with the pressure increase, which can remove the factors hinder the diffusion for example, the oxide film2.Zinc foil is used as the interlayer,under the parameters condition of 0.5MPa bonding pressure,380℃ bonding temperature and 1 hour holding time, shear strength of the joint can be up to 162MPa,which can also reach 93.6% of the base material strength. During the connection process, diffusion can become more homogenization with the improvement of the bonding temperature and holding time, but high temperatures and long holding time will produce intermetallic compounds segregation and reduce joint performance, increasing the pressure can improve the stability of diffusion, otherwise it will effect the process of the eutectic reaction of diffusion, which can result in unstable decomposition of intermetallic compounds.