Microstructural evaluation and mechanical properties of in-situ WC/W-Cu composites fabricated by rGO/W-Cu spark plasma sintering reaction

Highlights: • In-situ WC/WCu composite was fabricated by thermal reduction and spark plasma sintering. • WC formation at the interface improves wettability and interfacial bonding strength. • rGO/W-Cu composites exhibit high strength and hardness as well as relative density. In the current study, the reduced graphene oxide (rGO) was introduced into W-Cu composites for in-situ formation of WC particles using one-step thermal reduction and followed by spark plasma sintering reaction at 1050 °C for 10 min under a pressure of 80 MPa in a vacuum atmosphere. The microstructural characteristics, interface structure and mechanical properties of composite were investigated. The results exhibited that the GO flakes were effectively reduced to graphene in the rGO/W-Cu composites powders after reduction in hydrogen at 350 °C for 120 min. The relative density of rGO/W-Cu composites is higher than that of rGO-free composite that is attributed to the formation of some WC phases which can enhance the wettability between W and Cu in the sintering process. The formation of WC interlayer with thickness of about 8 nm at the W/Cu interface suggests that W and C atoms diffuse mutually and accumulate to form the carbides at the W-Cu interfaces in sintered rGO/W-Cu. The formation of WC at the interface can also enhance the interfacial bonding strength of W and Cu matrix. No evidence of W-Cu interfacial separation can be found in fracture surface, demonstrating positive effect of rGO on the interfacial strength of the composite.