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Microstructural Changes During Heat Treatment of Sintered Al 2 O 3
Author(s) -
MOCELLIN A.,
KINGERY W. D.
Publication year - 1973
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1973.tb12502.x
Subject(s) - grain growth , materials science , grain size , grain boundary , annealing (glass) , microstructure , growth rate , dopant , mineralogy , analytical chemistry (journal) , doping , crystallography , metallurgy , chemistry , geometry , mathematics , optoelectronics , chromatography
Samples of both high‐purity and Mg‐doped Al 2 O 3 sintered in H 2 , N 2 , O 2 , or vacuum were annealed at 1650° to 1850°C for times up to 64 h. In pore‐free systems, grain growth is limited by the mobility of Mg‐rich second‐phase inclusions; in samples annealed in H 2 , grain growth is limited by pore dragging with a transition toward limitation by solid‐inclusion dragging at high dopant levels; in samples annealed in N 2 and O 2 , grain growth is characterized by a transition from an “anchoring effect” of the pores toward a combination of pore dragging by and unpinning from the grain boundaries. Time‐dependence of grain growth is insufficient to determine the mechanisms and provide an adequate foundation for model‐based calculations. Observations of microstructure and its change with time, together with the rate of grain growth as a function of composition, allow elimination of alternate hypotheses and determination of the process which controls the rate of grain growth and change in pore size.