Processing and mechanical response of highly textured Al2O3

Dense, high quality textured alumina was fabricated by templated grain with only 0.14 wt% (SiO2 + CaO) and 1-15 wt% tabular alumina templates From stereological measurements, texture fraction was 95% and unaffected by template loading or dopant concentration. Due to the excellent template alignment during casting, the full-width at half the maximum (FWHM) of the rocking curve was exceptionally low at 4.6 degrees. Samples with the largest templated grains (1% templated alumina) have much lower strength (300-320 MPa) than those with smaller templated grains (400-500 MPa). Predominantly transgranular crack paths were observed in fracture surfaces both parallel and perpendicular to the oriented grains. The fracture toughness was anisotropic with slightly higher toughness perpendicular to the basal surface than parallel the direction grain basal surface. Surprisingly, the lowest density sample (93%) tested, which started with 15 wt% templates had the highest strength of 511 MPa +/- 0.45 and highest fracture toughness of 4.58 +/- 0.44 MPa m(1/2) when measured perpendicular to the basal surface of the grains. (C) 2010 Published by Elsevier Ltd.