|
SiC particle reinforced aluminum matrix composites have high specific strength and specific modulus, wear resistance, high temperature resistance, corrosion resistance, good thermal stability, etc., so that in the aerospace, automotive, electronics and medical and other fields with a wide range application prospects become metal matrix composites development and research of the mainstream. However, due to the special aluminum matrix composite structure led to its weldability is poor, difficult to form a high strength welded joints, such materials become a serious obstacle to practical use, therefore, the system of welding of aluminum matrix composites is imminent. Compared to other methods for welding, brazing with a heating temperature is low, the base material of reinforcement of small and welding deformation is small, simple operation. Based on this, silicon carbide particle reinforced aluminum matrix composites SiCp/101Al for the study, were used argon atmosphere furnace brazing and vacuum brazing process test, more in-depth analysis of the brazed aluminum matrix composites the formation process of the brazed aluminum matrix composite microstructure characteristics, mechanical properties and fracture characteristics and connection process on the joint microstructure and mechanical properties were investigated. The results show that: by selecting a reasonable solder, flux composition and the use of appropriate brazing process parameters, you can get good quality brazed joints. For both methods for soldering, brazing shear strength and hardness are brazed with the rise of temperature rise, but reaches a certain value, and with the rise of the brazing temperature reduced. Joint microstructure analysis, brazing solder melted, the molten base metal solder wetting and spreading of alloying elements between the base material interdiffusion occurs, the eutectic reaction occurs. Solder of Si, Cu and other alloy elements diffuse into the matrix base material, and in the Al matrix is ??incorporated by eutectic. Since Si has a crystal structure similar to the SiC, Si solder joints on the interface with SiC and a heterogeneous nucleation is nucleation and growth, so that the SiC and Al Si phase with a transition between the connection play a role in helping improve the interface between the brazing seam bonding quality. In addition, the brazing seam from the XRD pattern was found to contain Al-Cu, Al-Si eutectic phase, and the actually detected the presence of SiC phase; the brazing seam TEM observation confirmed the presence brazing seam SiC phase , indicating that some SiC reinforcement phase transition to the brazing seam being, to some extent, improve the mechanical properties of braze joints. Brazed joints fracture scanning observations indicate that most of the joints were tested ductile fracture, and most fittings are broken at the base metal parts that get the shear strength of brazed joints is relatively high. To sum up, the use of argon gas and vacuum brazing furnace brazing process SiCp/101Al composites even welding is feasible.
|