The 1300 °C Isothermal Section in the Al 2 O 3 -Y 2 O 3 -Nb 2 O 5 System

Phase stability in the Al 2 O 3 -Nb 2 O 5 -Y 2 O 3 ceramic system at 1300 °C was experimentally investigated. Disks samples fabricated from homogenized powders were uniaxially pressed at room temperature and heat treated at 1300 °C for 222 hours under laboratory atmosphere to achieve thermodynamic equilibrium. As results, the microstructures of the heat-treated samples did not exhibit pseudo-ternary phases and the phase relations confirmed nine three-phase fields in the proposed isothermal section at 1300 °C.