珠光体裂纹萌生与扩展的TEM原位观察

In Situ TEM Observation of Crack Initiation and Propagation in Pearlite

在透射电镜中进行动态拉伸原位观察珠光体裂纹萌生与扩展的微观过程。结果表明 :珠光体裂纹萌生与扩展方式取决于珠光体层片和拉伸轴的位向关系。当珠光体层片平行于拉伸轴时 ,裂纹在渗碳体和铁素体中交替萌生 ,垂直于层片扩展 ;当珠光体层片垂直于拉伸轴时 ,裂纹在铁素体中萌生 ,平行于层片扩展 ;当珠光体层片与拉伸轴斜交时 ,裂纹通过渗碳体和铁素体交替断裂而扩展 ;

The microprocess of crack initiation and propagation in pearlite under fensile loading has been investigated by in situ observation using a transmission electron microscope. The results indicate that the crack initiation and propagation mechanism depends on the orientation of pearlite lamellae with respect to the tensile axis. When the lamellae were parallel to the tensile axis, the crack initiated in ferrite and cementite alternatively, and then propagated perpendicular to the lamellae. When the lamellae were perpendicular to the tensile axis, the crack initiated and propagated in ferrite. When the lamellae made an angle with the tensile axis, the crack propagated alternatively in cementite and ferrite. Furthermore, the crack might initiate and propagate along the boundary of pearlite colonies.