Transformation and densification of nanocrystalline θ-alumina during sinter forging

C. Scott Nordahl, Gary L. Messing

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48 Scopus citations


The sinter forging behavior of α-Al2O3 seeded and unseeded nanocrystalline (θ-Al2O3 was investigated as a function of temperature, stress, and strain rate. Seeded samples exhibited the highest degree of plastic deformation during the θ- to α-Al2O3 phase transformation. As a result, microstructure control, increased densification, and a higher degree of transformation were obtained. A uniform microstructure of 150 nm α-Al2O3 grains developed, reaching 57% relative density after sintering 1.5 wt% α-Al2O3 seeded samples for 30 min at 1060°C. When sinter forged at 0.25 mm/min to 63 MPa and 1060°C for 30 min large deformations during the phase transformation increased the relative density to 74%. When the stress was increased to 235 MPa (1060°C, 30 min), 99.7% dense α-Al2O3 with a grain size of 230 nm was obtained. By increasing the sinter forging temperature to 1150°C, 99.5% relative density was achieved at 190 MPa for 30 min.

Original languageEnglish (US)
Pages (from-to)3149-3154
Number of pages6
JournalJournal of the American Ceramic Society
Issue number12
StatePublished - Dec 1996

All Science Journal Classification (ASJC) codes

  • Ceramics and Composites
  • Materials Chemistry


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