Grain Growth Behavior of Alumina Compact Processed by Controlled Fracture Forming.

Abstract

The effect of the green microstructure in the swaged Al2O3 with 98% reduction in area by the controlled fracture forming (CFF) on its grain growth behavior was investigated. The kinetics of grain growth in the Al2O3 compacts fabricated by the CFF process and by conventional process was estimated. The results indicate that both Al2O3 compacts obey a cubic law, but the grain growth rate constant K of the conventionally processed Al2O3 is 6 times as large as that of the swaged Al2O3 with 98% reduction in area. The retardation of grain growth in the swaged Al2O3 is attributed to the pores which are homogeneously distributed in the microstructure due to the flow and rearrangement of particles during the CFF process. The increase in number of pores per grain is responsible for the decrease in velocity of grain boundary migration. The mechanism for retardation of grain growth in the swaged Al2O3 is considered to be the pore-controlled mechanism.