Rietveld analysis and mechanical properties of in situ formed La-β-Al2O3/Al2O3 composites prepared by sol-gel method

Abstract

In this work, the crystal evolution of α-Al2O3 composites reinforced with LBA platelets were monitored by XRD Rietveld. In addition, the mechanical properties of totally densified specimens were researched by Vickers and Knoop indentations. These composite materials were prepared by a sol-gel process from alumina seeded boehmite sol and lanthanum nitrate. X-ray diffraction data have been studied by Rietveld refinements and line profile analyses, paying attention to the LBA formation, the evolution of vol%, and crystallite size of the different phases. It has been observed that the appearance of the LBA phase happens at a lower temperature than in samples prepared by a conventional solid state reaction. Indentation tests revealed that the presence of LBA microplatelets in the sol-gel samples leads to a significant increase of their indentation fracture resistance, in comparison to the conventional samples.