Grain size dependent residual microstresses in submicron A1 2O 3 and ZrO 2

Abstract

X-ray measurements of lattice spacings are used to determine residual microstresses present in sintered alumina and in tetragonal zirconia polycrystals due to thermal expansion anisotropy (TEA). In A1 2O 3 with grain sizes larger than 1 μm the microstresses are 30–100 MPa, in submicrometer samples the grain size influence becomes small and residual stresses range between 20 and 30 MPa. For the grain sizes between 0.3 and 9 μm there is no indication of a change in the high-temperature relaxation mechanism. In ZrO 2 with grain sizes of 0.5–1 μm the residual stresses are similar as observed in A1 2O 3 (20–60 MPa), they decrease further at grain sizes 0.2–0.4 μm. The results are independent of technological approaches like powder processing or sol/gel used to produce the sintered bodies.