Increasing joint strength by achieving carbon fibers’ continuity with ultrasonic assistance during soldering C_f/Al using ZnAl

Ultrasonic assistance was utilized during the soldering of carbon fiber-reinforced aluminum composites (C_f/Al) using ZnAl solder to enhance joint strength. The results indicated that carbon fibers migrated into the joint seam after Al substrate was eroded and the solder was expelled, effectively maintaining the continuity of the carbon fibers. A joint fully reinforced by carbon fibers was achieved with an ultrasonic application time of 60 s. Transmission electron microscopy revealed rapid wetting of the carbon fibers facilitated by ultrasound, characterized by an amorphous/nanocrystalline interface. The maximum joint strength reached 23.5 MPa, which is equivalent to 77.5 % of the C_f/Al.