Phase Transformation in Zone of Laser Treatment of Y2Ti2O7-Al2O3 Compositional Ceramics

The synthesis of Y2Ti2O7-Al2O3 compositional (multiphase) ceramics from powder mixtures Al2O3-Y2O3-TiO2 was carried out in two stages: 1) under the traditional sintering and then 2) in regime of directed laser heating. It was established that the sintering of mixtures with different content of components and the ratio of TiO2/Y2O3 = 2.34 in ceramic specimens the main phases are Y2Ti2O7 and α-Al2O3. The content of the main phases in ceramic materials also depends upon the oxide content in the initial mixtures. In ceramics the Y3Al5O12 is formed only at sufficiently high content of titanium and yttrium oxides in initial mixtures. In laser remelting, the phase composition is substantially different from that obtained at the traditional sintering, and depends on the mode of laser heating: irradiation power and the moving speed of the laser beam (i.e., heating temperature). Under certain conditions of laser remelting can be obtained superficial ceramic layer with crystallographic directional crystallization of Y2Ti2O7 and Al2O3 crystallites. The size of crystallites and the coefficient texturing also depend on the mode of laser treatment.