PARTICLE-INHIBITED GRAIN-GROWTH IN AL2O3-SIC .2. EQUILIBRIUM AND KINETIC-ANALYSIS

The grain-growth data presented in a companion paper for the Al2O3-SiC system are analyzed, Central to the analysis is the experimentally ob served relationship between the fraction of particles on grain boundar ies, phi, and the average grain size, G, This relationship is included in both the equilibrium-grain-size expression originally formulated b y Zener and classical grain-growth rate equations, The modified expres sion for equilibrium grain size, G(L), as a function of volume fractio n of pinning particles, f, contains a power-law dependence for G(L) on f that has been developed using the relationship between phi and G du ring microstructure evolution, The expressions for the grain-growth ki netics are similarly developed, The equilibrium and kinetic relationsh ips are used to describe the experimental data from the companion pape r and predict grain-growth behavior, A new type of map is constructed to predict the time required to approach equilibrium as a function of volume fraction and annealing temperature, This map reveals that extre me experimental conditions (very long times and high annealing tempera tures) are necessary for the system to reach equilibrium, especially f or smaller volume fractions, and that the attainment of equilibrium is experimentally quite difficult.