Synthesis, properties, and applications of functionally gradient cemented carbides

Cemented carbides have enjoyed widespread applications as a function of their outstanding properties during the past 100 years. Despite the advantages, however, recently there have been concerns about the challenges associated with traditional cemented carbides, i.e. the conflict of properties (hardness and toughness, strength and wear resistance) as well as the instability of reliability in service, necessitating the development of functional gradient cemented carbides (FGCCs). Although recent decades, investigations have seen explosive growth in FGCCs, there is still a lack of comprehensive review on FGCCs. Herein, the current study applies towards summarize the progress of FGCCs during the past 60 years, emphasizing the demand in FGCCs with tailored properties and customized requirements for specific applications. We initially introduce basic cognition of FGCCs, subsequently, comprehensively elucidate the gradient formation mechanisms of carburization, decarburization, nitridation, denitrification, infiltration process, and construction methods (solid-phase sintering, graphene doping and additive manufacturing etc.), then summary processing techniques and mechanical properties of FGCCs. In addition, the impart of additive on further improving the properties of FGCCs is discussed. Afterward, the possible applications of FGCCs at different areas are proposed. At the end of this paper, a summary of concluding remarks and potential developed direction of state-of-the-art FGCCs is provided.