AN ELECTRON MICROSCOPIC STUDY OF HYDROGEN EMBRITTLEMENT IN VANADIUM—II

Hydrogen embrittlement in vanadium was studied by in situ observation with a high-voltage electron microscope to reveal the formation of non-Maxwellian atmosphere of hydrogen atoms around a propagating crack-tip, the formation of hydride from the atmosphere by a displacive transformation and the microscopic processes of crack growth. The mechanism of formation of the non-Maxwellian atmosphere in a heterogeneously stressed system and the modes of crack growth of two types were discussed theoretically. A resistive force due to the atmosphere was considered to classify the crack growth into the above two types. The results of calculation on significant quantities related to the hydrogen embrittlement were compared satisfactorily with experimental results obtained.