Technology And Mechanism Of SiCp/Al Composite Ultrasonic Strengthening TLP Connection

Silicon carbide particle reinforced aluminum matrix composites(SiCp/Al-MMCS)have been developed rapidly in the fields of electronic packaging and aerospace industry due to their excellent properties.Ultrasound-assisted transient liquid phase connection(U-TLP)is an advanced connection method with high quality,high efficiency and low cost,which can realize fast connection of refractory materials in atmospheric environment.In this paper,ultrasonic assisted transient liquid phase(U-TLP)technology was used to connect SiCp/Al-MMCs with volume fraction of 70%,and pure zinc was used as the intermediate layer to study the influence of ultrasonic on the quality of welded joints.After welding,ultrasonic was applied again in the process of direct water quenching and isothermal solidification with the furnace cooling to obtain the interface bonding and microstructure evolution law of the joint.The direct influence of ultrasonic application on microstructure,SiC migration and properties of U-TLP welded joints is explored.The physical model of U-TLP at various stages was established and the mechanism of ultrasonic action was revealed.The experimental results showed that high volume SiCp/Al-MMCs can combined well in air environment and low temperature at 390?.Ultrasonic vibration can broke the oxide film on the surface of aluminum matrix composite,enhanced the wettability of silicon carbide particles and weld metal,promoted atomic diffusion and SiC particle uniform distribution,improved the welding quality and effectively shorten the welding time.At 20s applied by ultrasound,the oxide film has been thoroughly cleared and a complete joint was formed.Increase the ultrasonic vibration time reasonably promoted the uniformity of the welding area and effectively improved the joint strength,which can reached up to 89.6%of the base material.However,excessive increase of ultrasonic vibration time caused the extrusion of the liquid phase intermediate layer,resulted in the contact of the reinforcing phase particles in both sides of the base material and weak connection,which seriously affected the mechanical properties of the joint.Based on the analysis of microstructure and mechanical properties of welding seams,the effect of ultrasonic on microstructure of SiC particles reinforced aluminum matrix composites was revealed.It provided an important theoretical basis for further understanding the nature of U-TLP technology connection and promoted its application in the practical industry.