The influence of ZrO₂(Y₂O₃) ceramic grain size on hardness, fracture toughness and formation of transformation-deformation relief in the indentation zone

In this work, the hardness and fracture toughness of ZrO₂- 5.5 wt.% Y₂O₃ceramics with a grain size of 0.2, 0.5, 0.9, and 1.55 µm are determined by indentation methods. The deformation relief in the indentation zone and near a crack propagating from the crack angle in ZrO₂-Y₂O₃ceramics with different grain sizes was studied by atomic force microscopy. It is shown that the grain size of ZrO₂(Y₂O₃) ceramics has a significant effect on the hardness, fracture toughness of ceramics, and the deformation relief formed during indentation. It has been established that the larger the grain size, the lower the hardness of the material and the higher its fracture toughness. It is shown that with an increase grain size, the average height of the deformation relief increases from 20 to 140 nm. In ceramic specimens with a grain size of 0.5 μm or more, zones with a changed phase contrast are formed in the emerging deformation relief upon indentation. In ceramics with a grain size of 0.2 μm, zones with a changed phase contrast are not formed. The width of the zone with a changed phase contrast, measured near the indentation angle in the crack propagation region, increases from 0.6 to 1.7 µm, which correlates with the grain size of the studied ceramic. At the same time, quantitative analysis showed that the proportion of relief with a changed phase contrast increases from 11% in ceramics with a grain size of 0.5 µm to 27% in ceramics with a grain size of 1.55 µm, which is associated with a transformation transformation occurring in ceramics. during indentation.

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