Experimental Study On Contact Reactive Brazing And Diffusion Bonding Of Aluminum Alloy With High Silicon

High silicon aluminum alloy with good thermal conductivity, low expansion coefficient, good heat dissipation, light weight, is widely used in aviation, aerospace, automobile engine, electronic field. With used widely, the support of connection technology of high silicon aluminum alloy becomes more and more important. Because the surface of high silicon aluminum alloy with oxide film and it contains a large number of silicon, the welding performance is poor, the traditional welding method is difficult to obtain good performance of joints, contact reactive brazing and diffusion welding connection method is very good. In this paper, the high silicon aluminum alloy using the two kinds of welding methods are connectedIn the experiments, high silicon aluminum alloy is connected with the interlayer of Cu、Zn by the contact reactive brazing method and with the interlayer of Cu、Zn by the diffusion welding method. the welded materials are contacted each other by the forces provided by nuts during tightening. Macroscopic morphology, microstructure, distribution of elements were analyzed by means of metallography, scanning electron microscopy with energy dispersive spectrometer and connector micro-hardness were analyzed by vickers hardness.We discussed the influence of welding methods and different brazing parameters on joints.With the interlayer of Cu foil, Zn film, under appropriate conditions, the joins bonded effectively. According to testing results, the join bonded with Cu foil interlayer, healing temperature of 535℃ and holding time of 20min was relatively good. the weld region has ternary eutectic phase, massive primary Si phase and acicular eutectic silicon phase. The join bonded with Zn film interlayer, healing temperature of 405℃ and holding time of 20min was relatively good.With the interlayer of Zn film, the vacuum diffusion welding results showed that on the condition of temperature of 360℃,holding time of 70 minutes, the welding joint can obtain uniform diffusion layer. Whether the interlayer is Zn or Cu, heating temperature and holding time on the diffusion welding have a great impact, With temperature increasing, the diffusion reaction zone is broadening, if holding time is too short, atomic diffusion will be not sufficient, weld joint obtained will be not good, and holding time is too long, it is easy to form intermetallic compounds and the brittle phase.