PARTICLE-INHIBITED GRAIN-GROWTH IN AL2O3-SIC .1. EXPERIMENTAL RESULTS

An extensive experimental study has been conducted to examine the infl uence of ultrafine SiC particles on grain growth in Al2O3. Grain growt h has been studied as a function of annealing time, particle volume fr action, and annealing temperature, The SiC particles reduce the grain- growth rate of Al2O3 by >3 orders of magnitude, resulting in final gra in sizes that decrease with increasing particle volume fraction, The f raction of SiC particles on grain boundaries, phi, has been measured a s a function of annealing time, particle volume fraction, and annealin g temperature, phi decreases during grain-growth anneals, implying tha t grain boundaries are able to break free from particles and this is t rue to a greater extent for smaller volume fractions of particles, Fur ther, it has been discovered that phi and average grain size, G, are s trongly correlated, such that any increase in G results in a predictab le decrease in phi. This new finding has revealed a path for microstru cture development in this system that proves to be critical in the equ ilibrium and kinetic analyses described in a companion paper.