The microstructure and mechanical properties as well as the formation and morphological evolution mechanism of micro–nano TaC carbide prepared by an in situ casting–heat treatment reaction and chemical extraction method have been investigated. The size of the TaC particles was approximately 50–900 nm. The formation process and mechanism included nucleation growth of TaC grains and a diffusion-type solid-phase transition. Due to the “freezing” of the microstructure, the movement of the grain boundaries is inhibited, resulting in ultrafine TaC ceramic particles. The TaC particles preferably grow as cubes enclosed by {100} facets with minimized total surface free energy, indicating that both the intrinsic lattice structure and the growth conditions determine the final morphology of the TaC particles. In addition, the hardness and elastic modulus of the TaC ceramic were found to be 26.5 ± 0.4 GPa and 506.4 ± 5.8 GPa, respectively. Moreover, the fracture toughness was found to be 3.8 ± 0.1 MPa m^1/2. The toughening mechanism of the TaC ceramic layer includes crack deflection and crack bridging.

中文翻译：

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微纳米碳化钽陶瓷的原位制备

研究了通过原位铸造-热处理反应和化学提取方法制备的微纳米TaC碳化物的微观结构和力学性能以及形貌和演化机理。TaC颗粒的大小约为50-900 nm。形成过程和机理包括TaC晶粒的成核生长和扩散型固相转变。由于微结构的“冻结”，晶界的运动受到抑制，从而产生了超细的TaC陶瓷颗粒。TaC颗粒优选以由{100}小面包围的立方体的形式生长，具有最小的总表面自由能，表明内在的晶格结构和生长条件都决定了TaC颗粒的最终形态。此外，TaC陶瓷的硬度和弹性模量分别为26.5±0.4 GPa和506.4±5.8 GPa。此外，发现断裂韧性为3.8±0.1MPa·m。^1/2。TaC陶瓷层的增韧机理包括裂纹偏转和裂纹桥接。