IN SITU TEM OBSERVATION OF HYDROGEN-INDUCED CRACKING AND STRESS CORROSION CRACKING FOR Fe_3Al
Fe3Al氢致开裂和应力腐蚀的TEM原位观察

The change of dislocation configuration ahead of a loaded crack tip before and after charging with hydrogen, and stress corrosion cracking, and relationship between dislocation and initiation of hydrogen-induced cracking (HIC) for Fe3Al are investigated in TEM using a special constant deflection loading device. The results show that hydrogen can enhance dislocation emission, multiplication and motion, and increase the size of dislocation free zone (DFZ). A nanocrack of HIC will initiate and Dropagae in the DFZ when hydrogen enhanced dislocation emission and motion reach a critical condition. The reasons that hydrogen enhanced dislocation emission and motion, and the mechanism of initiation of HIC have been discussed.