The simultaneous bulk diffusion of 51Cr tracers in 20Ni-15Cr-1.45at%Si alloys, at 960 to 1400C, was measured by using the serial sectioning technique. At all temperatures, the diffusivities (table 172) were such that:

DCr > DFe > DNi

with DCr/DNi = 2.31 and DFe/DNi = 1.60. The activation enthalpies for diffusion of the major components in the alloy were quite close to each other. No correlation was found between swelling under irradiation, and the diffusion behavior of the major constituents. Grain boundary diffusion was found at surprisingly high temperatures.

S.J.Rothman, L.J.Nowicki, G.E.Murch: Journal of Physics F, 1980, 10[3], 383-98

 

Table 175

Hydrogen Permeation Parameters for JBK-75 in Various Conditions

 

Treatment

Po (mol/smMPa½)

E (kJ/mol)

cold-rolled to 75% deformation

0.000427

61.77

ST (980C, 1h), WC

0.000162

56.42

ST (980C, 1h), WC, aged (740C, 4h), AC

0.001060

66.27

ST (980C, 1h), WC, aged (740C, 8h), AC

0.000390

62.00

ST (980C, 1h), WC, aged (740C, 16h), AC

0.000504

63.65

ST: solution-treated, WC: water-cooled, AC: air-cooled