Improvement of High-temperature Creep Resistance in Polycrystalline Al<SUB>2</SUB>O<SUB>3</SUB> by Cations Co-doping

Abstract

High-temperature creep resistance in cations co-doped polycrystalline Al 2 O 3 was examined by uniaxial compression creep test at 1250°C. The dopant oxides used in this study were 0.1 mol% of YO 1 . 5 , ZrO 2 , SrO, MgO and TiO 2 . The creep rate in Al 2 O 3 was significantly changed by cations co-doping. For instance, Zr/Y co-doping suppressed the creep rate in Al 2 O 3 by a factor of about 400. A high-resolution transmission electron microscopy (HREM) and nano-probe energy dispersive X-ray spectroscopy (EDS) analysis revealed that Y and Zr cations segregate along grain boundaries. The grain boundary diffusion in Al 2 O 3 was supposed to be retarded by the segregation of Y and Zr cations. A first-principle molecular orbital calculation was made for cations co-doped Al 2 O 3 and cation singly doped Al 2 O 3 model cluster. The creep rate was correlated with the value of net charge in oxygen anion. The net charge of oxygen anion was one of the most important factors to determine the creep resistance in Al 2 O 3 .