Ultrafine WC-Co cemented carbides containing different (Ti,W)C content were fabricated by spark plasma sintering and the fracture mechanism and transverse rupture strength at high temperature were investigated. At ambient temperature, the strength of cemented carbides gradually decreases with the increasing (Ti,W)C. Meanwhile, the fracture behavior presents a mixed mode of intergranular fracture of WC grain boundaries and cleavage fracture of (Ti,W)C. As the temperature increases, the strength of all cemented carbides gradually decreases. At 900 °C, the degradation of materials caused by oxidation leads to a rapid reduction of strength. Compared to WC-Co, samples containing higher (Ti,W)C content present relatively gentle decrease trends of strength. In the substrate (non-oxidized part beneath oxide scales), the (Ti,W)C inhibits the oxygen diffusion at crack tips, which reduces fracture paths along oxidized grain boundaries. At high temperature, the oxidation damage of grain boundaries and brittle-ductile transition of substrate have important effects on the fracture behavior.

通过火花等离子体烧结制备了不同（Ti，W）C含量的超细WC-Co硬质合金，并研究了高温下的断裂机理和横向断裂强度。在环境温度下，硬质合金的强度随着（Ti，W）C的增加而逐渐降低。同时，断裂行为呈现出WC晶界的晶间断裂和（Ti，W）C的劈裂断裂的混合模式。随着温度升高，所有硬质合金的强度逐渐降低。在900°C下，由氧化引起的材料降解会导致强度快速降低。与WC-Co相比，（Ti，W）C含量较高的样品呈现出相对平缓的强度下降趋势。在基材（氧化皮下方的未氧化部分）中，W）C抑制了氧在裂纹尖端的扩散，从而减少了沿着氧化晶界的断裂路径。在高温下，晶界的氧化损伤和基体的脆韧性转变对断裂行为具有重要影响。