Influence of in situ dysprosium aluminate garnet formation on sintering of reaction sintered magnesium aluminate spinel

In the present study, commercially available different sources of magnesia and alumina were used to produce reaction sintered magnesium aluminate spinel (MgAl2O4). Initially, spinel with stoichiometric composition was prepared from three different sources of Al2O3 and two sources of MgO and then the effect of dysprosia (Dy2O3) in a concentration range of 1-4 wt.% on the sintered properties of spinels was studied in the temperature range of 1550-1650 degrees C. The densities of the doped compositions were higher compared with the undoped ones, and the maximum density was found for the 1 wt.% Dy2O3-doped samples. Phase analysis and microstructural studies revealed that formation of dysprosium aluminum garnet (Dy3Al5O12) phase along the intergranular positions, which served as grain-growth inhibitors and improved densification. Further, 1 wt.% Dy2O3-doped compositions also revealed better flexural strength and retained strength post thermal shock values than undoped spinel.