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用透射电子显微术(包括弱束技术)对WC-12%Co硬质合金的形变和裂纹扩展过程及粘结相的相变机制进行了电子衍衬研究。研究指出:合金的形变行为取决于粘结相Co的协调应变的能力,裂纹扩展的特征形貌和WC及Co相的滑移结构及界面的性质有直接关系。裂纹在WC中、在WC/WC以及WC/Co界面呈直线传播,而在粘结相中则表现为“Z”字形特征。β-Co(fcc结构)在室温下不稳定,在不大的相变驱动力(例如,合金承受形变)作用下,很容易向hcp结构的ε-Co转变。这种转变的过程是:经由β-Co中的层错片加厚和长大,最终形成稳定的hcp结构ε-Co。
The electron diffraction study of the deformation and crack propagation of WC-12% Co cemented carbide and the phase transition mechanism of the binder phase were carried out by transmission electron microscopy (including weak beam technique). It is pointed out that the deformation behavior of the alloy depends on the ability of the cohesive strain of the cohesive phase. The characteristic morphology of the crack propagation is directly related to the slip structure and interface properties of the WC and Co phases. Cracks propagate linearly in the WC, WC / WC and WC / Co interfaces, and “Z” -shaped features in the binder phase. β-Co (fcc structure) is unstable at room temperature, and it is easy to change ε-Co of hcp structure under the action of a small phase change driving force (for example, the alloy undergoes deformation). The process of this transformation is to form a stable hcp structure ε-Co through the thickening and growth of stacking faults in β-Co.