Superplastic deformation of transparent hydroxyapatite

Transparent, nanocrystalline hydroxyapatite with an average grain size of 170 nm was fabricated by spark plasma sintering. The superplastic flow behavior of the hydroxyapatite specimen was examined at temperatures ranging from 950 to 1050 °C. The hydroxyapatite specimens exhibited superplasticity under the test conditions examined. A maximum elongation of 486% was achieved at 1000 °C and an initial strain rate of 1.0 × 10–4 s−1. The excellent tensile ductility in transparent, nanocrystalline hydroxyapatite was attributed to the very fine grain size and pore-free microstructure.