SOLUTE ACCELERATION VERSUS ZENER DRAG FOR CONTROLLING MICROSTRUCTURAL EVOLUTION OF ALUMINA

The microstructure of a sintered body strongly depends on the composition of the powder used for the sintering process, where dopants and impurities are known to affect sintering and grain growth. In addition, second phase particles are also known as grain growth inhibiters, inducing Zener drag on the grain boundaries. In this study, nickel alumina nanocomposites were doped with CaO at a concentration below the solubility limit. Unlike segregating dopants which reduce grain boundary mobility by solute-drag, CaO increases the rate of grain growth. The goal of this study was to understand the influence of Ni particles on the increased grain boundary mobility (due to CaO) and microstructural evolution of alumina. The amount of CaO in the alumina was determined by conducting fully standardized wavelength dispersive spectroscopy (WDS) and the change in grain boundary mobility was characterized using scanning electron microscopy.