In situ measurements of the high-temperature mechanical properties of ZrO2-doped YTaO4 ceramic by three-point bending combined with a digital image correlation method

ZrO2-doped YTaO4 ceramics with different ZrO2 contents (Y1-xTa1-xZr2xO4 ceramics, 2x = 0, 0.1, 0.15, 0.2) are prepared by a solid-state reaction method. The high-temperature mechanical properties are determined by an in situ high-temperature three-point bending combined with the digital image correlation (DIC) method. The results show that when the temperature rises from 25 degrees C to 800 degrees C, the temperature dependence of the elastic modulus, fracture toughness and fracture strength with a ZrO2 doping content of 10% mol is relatively small. The elastic modulus, fracture toughness and fracture strength decrease from 105.4 GPa to 96.1 GPa, from 2.6 MPa m(1/2) to 2.3 MPa m(1/2) and from 73.8 MPa to 64.8 MPa, respectively. Transgranular fracture is the main fracture mode. When the crack propagates through the twin band, a phase transformation and a typical domain change occur. Furthermore, the crack propagating through the twin band at room temperature (25 degrees C) is more tortuous than that at 800 degrees C, and more energy needs to be consumed. This illustrates that the fracture toughness and fracture strength at room temperature (25 degrees C) are higher than those at high temperature.