Grain boundary energy, disordering energy and grain growth kinetics in nanocrystalline MgAl2O4 spinel

Abstract An atomistic description and quantification of the individual contributions coming from the driving force and the grain boundary mobility to the phenomenon of grain growth can result in a better understanding and control of the microstructural evolution. The present work addresses these topics concerning nanocrystalline dense MgAl 2 O 4 . A systematic experimental investigation is performed on MgAl 2 O 4 spinel using Differential Scanning Calorimetry (DSC) to determine the grain boundary energy as function of the grain size ranging from ∼8  nm to ∼150  nm to quantify the thermodynamic driving force for grain growth. The grain boundary energy displays a strong dependence on the grain size along with additional increase in excess energy with decreasing grain size as a result of a size-induced cation site disorder (inversion). A grain growth study is performed at temperatures ranging from 1100 to 1300 °C in order to determine both grain boundary mobility and activation energy. The results demonstrate faster growth behavior for smaller grains that can be related to a combined increase in excess energies and grain boundary velocities with decreasing grain size.