ODS铁素体钢中微裂纹形核过程的TEM原位观察

IN SITU OBSERVATIONS OF MICROCRACK NUCLEATION IN ODS FERRITIC STEEL

采用透射电子显微镜原位拉伸薄膜试样法研究了ODS铁素体钢中位错发射及微裂纹形核、钝化和扩展的过程．结果表明，ODS铁素体钢在原位拉伸时，裂尖首先发出大量位错并形成无位错区，保持恒位移，纳米级微裂纹在裂纹顶端连续形核或在DFZ中不连续形核，这个微裂纹并不钝化成孔洞．

Dislocations were emitted from a crack tip, and nucleation, blunt and propagation of a microcrack with a nanometre in size are studied through in situ tensile test for thin foil speCimens of ODS ferritic steel by transmission electron microscopy (TEM). The results show that dislocations are emitted from a crack tip and a dislocation free zone (DFZ) forms in front of the crack tip. Under the condition of constant displacement, the microcracks nucleate continuously at the crack tip or discontinuously in the DFZ, and they are not blunted into voids.