The non-linear enhancement of solvent diffusion by Ge was measured (table 201) at 1330 to 1470K, using 59Co rather than a Ni tracer. By using a suitable model, vacancy-impurity binding free enthalpies of about –0.20eV were estimated from the enhancement factors.

F.Faupel, C.Kostler, K.Bierbaum, T.Hehenkamp: Journal of Physics F, 1988, 18[2], 205-12

 

Table 198

Diffusivity of H in GH761

 

Heat Treatment

Do (m2/s)

E (kJ/mol)

1090C, 2h; wc

4.61 x 10-7

49.80

1090C, 2h; wc; 850, 4h; ac

1.91 x 10-7

60.93

1090C, 2h; wc; 850, 4h; ac; 750C, 24h; ac

1.23 x 10-7

60.39

1090C, 2h; wc; 770, 4h; ac

6.37 x 10-7

57.01

ac: air-cooled, fc: furnace-cooled