Particle-inhibited grain growth in Al2O3-SiC .1. Experimental results

An extensive experimental study has been conducted to examine the influence of ultrafine SiC particles on grain growth in Al2O3. Grain growth has been studied as a function of annealing time, particle volume fraction, and annealing temperature, The SiC particles reduce the grain-growth rate of Al2O3 by >3 orders of magnitude, resulting in final grain sizes that decrease with increasing particle volume fraction, The fraction of SiC particles on grain boundaries, phi, has been measured as a function of annealing time, particle volume fraction, and annealing temperature, phi decreases during grain-growth anneals, implying that grain boundaries are able to break free from particles and this is true to a greater extent for smaller volume fractions of particles, Further, it has been discovered that phi and average grain size, G, are strongly correlated, such that any increase in G results in a predictable decrease in phi. This new finding has revealed a path for microstructure development in this system that proves to be critical in the equilibrium and kinetic analyses described in a companion paper.