Microstructures and sintering kinetics of pressureless sintered alumina doped with diopside and AlTiB

► Sintering densification process of the composites was studied. ► The apparent activation energies were calculated. ► The sintering kinetic equations were deduced. ► The sintering mechanism of monolithic Al2O3 was volume diffusion. ► The sintering mechanism of composites was volume diffusion and grain boundary diffusion.