Initial Coarsening and Microstructural Evolution of Fast-fired and MgO-doped Al₂O₃


Green, David J. and Halloran, John and Johnson, David W. and Klein, Lisa


The effect of an initial coarsening step (50-200 h at 800°C) on the subsequent densification and microstructural evolution of high-quality compacts of undoped and MgO-doped Al2O3 has been investigated during fast-firing (5 min at 1750°C) and during constant-heating-rate sintering (4°C/min to 1450°C). in constant-heating-rate sintering of both the undoped and MgO-doped Al2O3, a refinement of the microstructure has been achieved for the compact subjected to the coarsening step. a combination of the coarsening step and MgO doping produces the most significant refinement of the microstructure. in fast-firing of the MgO-doped Al2O3, the coarsening step produces a measurable increase in the density and a small refinement of the grain size, when compared with similar compacts fast-fired conventionally (i.e., without the coarsening step). This result indicates that the accepted view of the deleterious role of coarsening in the sintering of real powder compacts must be reexamined. Although extensive coarsening after the onset of densification must be reduced for the achievement of high density, limited coarsening prior to densification is beneficial for subsequent sintering.


Materials Science and Engineering

International Standard Serial Number (ISSN)

0002-7820; 1551-2916

Document Type

Article - Journal

Document Version


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© 1997 Wiley-Blackwell, All rights reserved.

Publication Date

01 Jan 1997