High heating rate effects in sintering: A phase-field study of La-doped alumina

Sintering is a widespread manufacturing process, accounting for a significant portion of global energy expenditure. However, controlling this process has been mostly a trial-and-error process, being costly in both time and money. The recent advance of high heating rate sintering methods, which promise higher energy efficiency and better properties, only adds to this. This paper aims to reduce these costs by shedding light on the microstructural evolution during high heating rate sintering, which will allow for quicker parameter optimization and improved properties. The focus will be on how a representative microstructure changes locally as well as globally while resolving grains and the green body at scale, which no prior paper has done. A representative multiphysics phase-field solver is employed, incorporating a novel particle-based temperature model, which recovered many characteristics typical of high heating rate sintering. Comparing the simulation data to experimental data showed reasonable agreement over a large density range without parameter adjustment. Furthermore, the advance of a sintering front including grain growth effects could be shown simulatively for the first time in literature. These findings suggest that the model can be used for the design of practical heating schedules for the sintering of novel materials. • A novel multiphysics phase-field model of sintering accounting for temperature, applicable to any metal and/or ceramic materials system is presented. • A novel particle-based temperature model allows efficient upscaling to the parts scale and reduces time integration effort. • Many characteristics of high heating rate sintering are recovered & simulated densification rates are shown capable of matching experiments. • Green bodies with Biot numbers below 0.017 can be assumed homogeneous in both temperature and microstructure. • Green bodies with higher Biot number were observed to develop sintering fronts, which can be exploited to still obtain homogeneous microstructures from temporary inhomogeneous evolution.