Brazing of graphite to Cu with Cu50TiH2 + C composite filler

Abstract

Brazing of graphite to Cu has been successfully realized with Cu50TiH2 (containing 50 wt% Cu)-based fillers (including Cu50TiH2 filler and Cu50TiH2 + C composite filler) in vacuum at 1223 K. The average shear strength is 10.8 MPa for the joints brazed with Cu50TiH2 filler. Microstructure observation of the joints shows the crack-free interfaces both at the graphite and the Cu sides. The filler layer mainly consists of Cu base solid solution and Ti–Cu intermetallics. Furthermore, a thin TiC reaction layer is developed close to the graphite substrate. With regard to the joints brazed with Cu50TiH2 + C composite filler, the average shear strength of the joints increases to 18.0 MPa. Microstructural characterization reveals that TiC particles have been synthesized in situ in the filler layer. Cu base solid solution and Ti–Cu intermetallics together with TiC particles are detected in the filler layer. The TiC particles synthesized in situ distribute uniformly in the filler layer, which may act as reinforcements and consequently benefit the improvement of the graphite/Cu joints.