The volume and grain-boundary diffusivities of 59Fe in a high-purity Fe-50Cr-8wt%W alloy were determined at 1023 to 1373K (figure 23) by using the sputter micro-sectioning technique. The bulk diffusion coefficients of Fe in the Fe-50Cr-8W alloy were smaller than those in high-purity Fe-50wt%Cr alloy. Linear Arrhenius plots were observed for the bulk self-diffusion coefficients over the present temperature range. The activation energy for bulk diffusion in the Fe-50Cr-8W alloy was somewhat smaller than that in the Fe-50Cr alloy. On the other hand, the grain-boundary diffusivity of Fe in the Fe-50Cr-8W alloy at 1123K was about 2 orders of magnitude lower than that in the Fe-50Cr alloy. The grain-boundary diffusivity of Fe at 1123K was equal to 2.7 x 10-21m3/s, and that at 1323K was equal to 1.4 x 10-19m3/s.

K.Takasawa, Y.Yamazaki, S.Takaki, K.Abiko, Y.Iijima: Materials Transactions, 2002, 43[2], 178-81

Figure 23

Diffusivity of 59Fe in Fe-50Cr-8W and Fe-50wt%Cr