A gaseous permeation technique was used to measure the H permeabilities and diffusivities of specimens, after various heat treatments, at temperatures ranging from 210 to 430C. The results (tables 175 and 176) showed that the temperature dependences of the H permeabilities and diffusivities in the various alloys obeyed Arrhenius relationships over the studied temperature range. Also, the H permeation behavior was essentially independent of the heat-treatment conditions. That is, it was not significantly affected by the presence of ' precipitates in the alloys. The H permeation parameters of the Fe-based superalloys were essentially consistent with those of austenitic stainless steels. The transport of H in these face-centered cubic alloys was generally controlled only by the lattice diffusion of H.
J.Xu, X.K.Sun, W.X.Chen, Y.Y.Li: Acta Metallurgica et Materialia, 1993, 41[5], 1455-9
Table 178
Coefficients for 59Fe Diffusion in Thin Films of Fe40Ni40P14B6
Temperature (C) | Coefficient (m2/s) |
150 | 1.2 x 10-24 |
170 | 8.3 x 10-23 |
200 | 1.5 x 10-22 |
230 | 3.5 x 10-22 |
256 | 6.7 x 10-22 |
300 | 2.5 x 10-21 |
Figure 26
Diffusivity of D in Crystalline Fe40Ni40P14B6
(open squares: vacuum ambient, filled squares: air ambient)