The effect of the redox potential of annealing environment on the mechanical properties of Al2O3-YAG:Ce eutectics

Mechanical characteristics of the eutectics Al2O3-Y3Al5O12:Ce grown by the method of horizontal directional crystallization were established. The influence of the redox potential of the annealing environments on the microhardness and fracture toughness of Al2O3-Y3Al5O12:Ce eutectics has been investigated. Three kinds of environments that differed by the redox potentials have been applied: oxidizing (in the air), in a vacuum, and reducing (Ar. CO, H2). The obtained results showed that doping with Ce ions deteriorates the mechanical properties of the Al2O3-YAG eutectic, both microhardness and fracture toughness. Annealing improves the mechanical properties of the eutectic for all concentrations of Ce ions, but the value of the redox potential of the annealing environment does not affect the degree of the enhancement of these mechanical properties. Only vacuum annealing has a stronger effect on the fracture toughness of eutectics. The increase in microhardness in samples with Ce after annealing is more noticeable compared to samples without Ce. Despite the anisotropy of the eutectic morphology and crystalline texture of the constitutional phases, the mechanical properties of the eutectics didn't depend noticeably on the direction in the ingot.