カソード分極に伴う50.9at%Ni-Ti合金の水素脆化

抄録

To clarify the cause of delayed fracture of a glasses frame made of Ni-Ti alloy and to establish an appropriate countermeasure against hydrogen embrittlement, the diffusion coefficient of hydrogen D_H in a 50 9at%Ni-Ti alloy and changes in the load-elongation curve due to cathodic polarization were investigated. Cathodic polarization introduced large amounts of hydrogen. D_H was calculated from the polarization time dependence of the hydrogen content, and the temperature dependence of D_H was obtained to be D_H=257×10^-7(m²/s) exp (-382(kJ/mol)/RT). Cathodic polarization caused hydrogen embrittlement. A marked decrease in elongation occurred as the polarization time and the aging time at room temperature after polarization increased. This is attributed to an increase in the penetration depth of hydrogen.