Confirming Vacuum Brazing Temperature for SiC_p/A356 Composite Containing SiCp with Low Volume Fraction

Taking Ag47-Cu18-In17-Sn17-Ti1 as brazing filler metal, SiCp/A356 composites containing 15vol% SiCp were welded by using vacuum brazing technology under the parameters of temperature 560 ℃, 570 ℃, 580 ℃ and soaking for 30 minutes. Microstructure, microhardness and shear strength of the joints were investigated, and then optimal brazing temperature was confirmed. The result indicate that in the brazing temperature range of 560-580 ℃, the compact brazed seam obtained. The brazing filler metal could wet both of the matrix aluminum alloy and SiC particles very well. The diffusion distance of elements in brazing filler metal at 580 ℃ was much longer than that at 560 ℃. The microhardness in brazed seam centre area and diffusion area gradually decreased with the increase of brazing temperature. The optimal brazing temperature was 560 ℃. At this temperature, the maximum shear strength of the jonts could reach 51.8 MPa, and the microhardness in brazed seam centre area and diffusion area was 99.4 HV and 110.7 HV, respectively. The fracture mechanism of the joint was characterized by ductile fracture.