Microstructural and mechanical properties of nanocrystalline spinel and related composites

Magnesium aluminate spinel (MgAl2O4) is known for its excellent deformation behavior at high temperatures. By retaining nanocrystalline grain size after densification, the extent of deformation can be further enhanced. In this work, nanocrystalline MgAl2O4 and composites were densified by hot isostatic pressing (HIPing). One of the objectives of this paper is to report the phase content and microstructural characteristics of these dense nanocomposites. Another objective is to investigate room temperature as well as high temperature mechanical properties of these materials. The present data were compared with the existing literature for coarse grained materials. The hardness values ranged between 2.89 and 7.79 GPa and fracture toughness ranged between 2.5 and 5.82 MParootm. Hot hardness results showed that at least in one composition, a significant reduction in hardness occurred at 1000 degreesC. (C) 2002 Elsevier Science Ltd and Techna S.r.l. All rights reserved.