Abstract: Transparent Mg-Al spinel ceramics MA1. 0, MA1.3, MA1.5 and MA1.8 was fabricated from MgO · nAl2O3 powder with n of 1. 0, 1.3, 1.5 and 1.8, respectively. These ceramics were sintered to be transparent through two combined sintering processes, i.e. vacuum sintering followed by hot isostatic pressing (HIP). Relative density of these ceramics decreases with n in MgO · nAl2O3 increasing because of second phase Al2O3 grains appearing in non-stoichiometric ceramics MA1.3, MA1.5 and MA1.8 during preparation. However, these non-stoichiometric ceramics show higher mechanical properties than ceramic MA1. 0. Fractural surfaces of non-stoichiometric ceramics observed by scanning electron microscopy (SEM) are featured with more transgranular fracture which contributes to improving their mechanical properties.

Key words: Transparent Mg-Al spinel ceramics MA1. 0, MA1.3, MA1.5 and MA1.8 was fabricated from MgO · nAl2O3 powder with n of 1. 0, 1.3, 1.5 and 1.8, respectively. These ceramics were sintered to be transparent through two combined sintering processes, i.e. vacuum sintering followed by hot isostatic pressing (HIP). Relative density of these ceramics decreases with n in MgO · nAl2O3 increasing because of second phase Al2O3 grains appearing in non-stoichiometric ceramics MA1.3, MA1.5 and MA1.8 during preparation. However, these non-stoichiometric ceramics show higher mechanical properties than ceramic MA1. 0. Fractural surfaces of non-stoichiometric ceramics observed by scanning electron microscopy (SEM) are featured with more transgranular fracture which contributes to improving their mechanical properties.