IN-SITU OBSERVATIONS ON DISLOCATION BEHAV IOR AND THE EFFECT OF HYDROGEN NEAR THE CRACK-TIP IN Fe-3%Si SINGLE CRYSTAL BY TEM
Fe—3%Si 单晶体裂纹尖端位错行为及氢效应的 TEM 动态观察~*

Dislocation behavior and effect of hydrogen have been observed near thecrack-tip in Fe-3%Si single crystal during in-situ deformation in an electron microscope.It has been found that a number of dislocations were emitted from the crack-tip duringdeformation and moved away quickly from the crack-tip region creating a dislocation-freezone (DFZ).The dislocations stored in the plastic zone were in a form of an inversepile-up.The propagation of the crack-tip includes two processes,i.e.the plastic process inwhich a number of dislocations were emitted from the crack-tip by crack-tip deformationand the brittle process in which the cleavage of DFZ occured.The solute hydrogen can change the distribution of dislocations near the crack-tip andcan lead to the diminution and even disappearance of the DFZ.