Grain growth kinetics and grain refinement mechanism in Al2O3/WC/TiC/graphene ceramic composite

The grain growth kinetics and grain refinement mechanism of Al2O3 grains and WC grains in Al2O3/WC/TiC/graphene ceramic composite were investigated in this work. The grain growth exponent of Al2O3 was determined as 2, which conformed to the growth mechanism of grain boundary diffusion. Meanwhile, the grain growth exponent of WC was determined as 3, which conformed to the grain growth mechanism of volume diffusion or liquid-phase diffusion. The different wettability of graphene to Al2O3 and WC was responsible for their different grain growth mechanisms. By analyzing grain growth activation energy, it can be concluded that the grain growth of Al2O3 and WC went through three stages: (1) softening stage, (2) rapid growth stage and (3) stable stage. The grain refinement mechanism of Al2O3 grains was graphene pinning effect and intragranular structure, and the grain refinement of WC grains could be attributed to the strong bonding interface between WC and graphene.