The role of foam on microstructure and strength of the brazed C/C composites/Ti6Al4V alloy joint

C/C composites and Ti6Al4V alloy had been brazed and the Cu foam was used as an interlayer to inhibit the formation of brittle compounds in the brazing seam. Adding Cu foam interlayer had caused the significant change in the microstructure of joint. An infiltration zone was formed at the C/C composite side and perpendicular to the bonding interface, and Ti was the primary element of infiltration zone. The brazing seam was composed of (Cu(s,s)) and Ag(s,s), and reaction layer close to Ti6Al4V alloy side contained many layers. Adding Cu foam decreased the hardness value of brazing seam to 77.6 HV. The decrease in hardness of brazing seam and reaction layer was beneficial to improving reliability of joints. Thermal cycle lifetime of joints increased by nearly 2 times after adding foam.