Particle‐Inhibited Grain Growth in Al2O3‐SiC: II, Equilibrium and Kinetic Analyses

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Abstract
The grain‐growth data presented in a companion paper for the Al2O3‐SiC system are analyzed. Central to the analysis is the experimentally observed relationship between the fraction of particles on grain boundaries, φ, and the average grain size, G. This relationship is included in both the equilibrium‐grain‐size expression originally formulated by Zener and classical grain‐growth rate equations. The modified expression for equilibrium grain size, GL, as a function of volume fraction of pinning particles, f, contains a power‐law dependence for GL on f that has been developed using the relationship between φ and G during microstructure evolution. The expressions for the grain‐growth kinetics are similarly developed. The equilibrium and kinetic relationships are used to describe the experimental data from the companion paper and predict grain‐growth behavior. A new type of map is constructed to predict the time required to approach equilibrium as afunction of volume fraction and annealing temperature. This map reveals that extreme experimental conditions (very long times and high annealing temperatures) are necessary for the system to reach equilibrium, especially for smaller volume fractions, and that the attainment of equilibrium is experimentally quite difficult.

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