Brazing of SiC ceramic to Al0.3CoCrFeNi high entropy alloy by graphene nanoplates reinforced AgCuTi composite fillers

Graphene nanoplates reinforced AgCuTi composite fillers are applied to braze SiC ceramic with Al0.3CoCrFeNi high entropy alloys. Graphene nanoplates, together with active element Ti which could restrain the activity of multiple elements from Al0.3CoCrFeNi, impede the intense diffusion towards SiC and thus avoid the formation of bulk brittle compounds unfavorable to the joint performance. The in situ synthesized reaction between Ti and graphene nanoplates leads to dispersive TiC reinforcements which not only promote the refinement of the joint microstructure but also relieve the residual stress that existed in SiC/Al0.3CoCrFeNi joint. Vigorous dissolution and diffusion across Al0.3CoCrFeNi/liquidus filler interface lead to laminated Ti-rich layers formed adjacent to Al0.3CoCrFeNi substrate. The uniform and continuous reaction layer of TiC/Ti2Ni-type compounds/Ag(Cu) in-clusions is formed adjacent to SiC ceramic. Tiny TiC particles and Ti2Ni-type compounds distribute evenly in the brazing seam, strengthening the joint performance. Eventually, the maximum shear strength of 36.7 MPa is achieved when adding 0.3 wt% graphene nanoplates.