Grain-Size Dependence of the Hardness of Submicrometer and Nanometer Hydroxyapatite
Dense hydroxyapatite (HA) bodies (at 99% of the theoretical density or higher) with grain sizes ranging from 67 to 732 nm have been obtained via a process of morphology-enhanced low-temperature sintering at temperatures as low as 850°C. The Knoop indentation study reveals that the hardness of HA exhibits a linear dependence on the inverse square root of the grain diameter, consistent with the Hall–Petch relationship. This is the first report of the grain-size dependence of the HA hardness in the nanometer range, and the phenomena observed suggest that the deformation of HA under indentation is dislocation mediated.
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Document Type: Research Article
Affiliations: Department of Chemical, Materials and Biomolecular Engineering, Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269
Publication date: 2010-03-01