Synthesis and microstructural characterization of α-Al2O3–t-ZrO2 composite powders prepared by combustion technique

α-Al2O3–ZrO2 composites with various wt. fractions were prepared from metal nitrates by a combustion technique. A detailed study on the phase stability of ZrO2 in the tetragonal phase at room temperature and near its transformation temperature and its microstructural features in the α-Al2O3 matrix has been conducted using X-ray structural and microstructural refinement, TEM and Raman spectroscopy. It is observed that the tetragonal ZrO2 is stabilized in an alumina matrix up to a wt. fraction of ∼0.58. The crystallite size (54 nm), obtained from the X-ray diffraction analysis, is in accordance with TEM studies (65 nm). The size value is well above the critical size limit as reported in the literature. It is found that microstrains also play a significant role in the stabilization process.