Abstract
The diffusion of hydrogen in nickel and copper, and in fcc nickel-copper and nickel-cobalt alloys has been investigated over the temperature range from 260 to 1000 K by a technique of electrochemical permeation and a technique of gas phase permeation. The temperature dependence of the diffusion coefficient of hydrogen (D) in nickel and copper is described as follows: In nickel, D(m2⁄s)=9.2×10−7exp(−41.4(kJ/mol)⁄RT), and in copper, D(m2⁄s)=9.0×10−7exp(−43.5(kJ/mol)⁄RT). Arrhenius plots of D in Ni–Cu and Ni–Co alloys can also be represented by straight lines. The activation energy for diffusion of hydrogen changes with the concentration of alloying element. It has a maximum at 70 at% Cu in Ni–Cu alloys and increases with increasing concentration of Co in Ni–Co alloys.
The solubility of hydrogen (S) in nickel, copper, Ni–Cu alloys and Ni–Co alloys has been measured by a gas phase permeation method at temperatures between 560 and 1000 K. The temperature dependence of S in nickel and copper is given by S(mol H2⁄(mol Ni Pa1⁄2))=2.2×10−6exp(−10.8(kJ/mol)⁄RT) in nickel and S(mol H2⁄(mol Cu Pa1⁄2))=1.4×10−5exp(−37.6(kJ/mol)⁄RT) in copper. Arrhenius plots of S in Ni–Cu and Ni–Co alloys can also be represented by straight lines. The solution enthalpy of hydrogen has a minimum at 30 at%Cu alloys and increases with increasing concentration of Co in Ni–Co alloys.
