The diffusion coefficients were measured at temperatures ranging from 489 to 774K. The 16O was injected via ion implantation. The diffusion penetration profiles were then measured by exploiting the 16O(d,p)17*O nuclear reaction. The temperature dependence of the O diffusivity was described by:

D (m2/s) = 1.3 x 10-6 exp[-121.6(kJ/mol)/RT]

It was found that the addition of Si and Al hardly affected O diffusion, whereas the addition of Fe, Nb or B decreased the diffusivity by 20 to 70%, and the addition of Cr or Mo decreased the activation energy by 10 to 15% (table 315). The most marked alloying effect was observed in the case of the V-3Ti-2Si and V-5Ti alloys. The diffusivity in V-5Ti was about 2 orders of magnitude lower than that in V. It was concluded that this was evidence for a trapping effect due to Ti, and the binding energy was estimated to be about 52kJ/mol.

H.Nakajima, S.Nagata, H.Matsui, S.Yamaguchi: Philosophical Magazine A, 1993, 67[3], 557-71

 

Table 318

Diffusivity of 16O in V Alloys

 

Material

Temperature (K)

D (m2/s)

V-0.1Al

673

6.77 x 10-16

V-0.1Al

623

9.30 x 10-17

V-0.1Al

574

8.65 x 10-18

V-0.1Al

532

1.44 x 10-18

V-0.1Al

494

1.13 x 10-19

V-0.1B

624

6.70 x 10-17

V-0.1B

574

8.50 x 10-18

V-0.1B

524

6.04 x 10-19

Table 319

Diffusion Coefficients for 60Co in V-Co Alloys

 

Co(at%)

Temperature(K)

D (m2/s)

0

1521

6.20 x 10-15

0

1438

1.87 x 10-15

0

1403

9.3 x 10-16

0

1337

2.6 x 10-16

0.5

1521

7.95 x 10-15

0.5

1438

1.99 x 10-15

0.5

1403

1.10 x 10-15

0.5

1337

3.3 x 10-16

1.0

1521

8.49 x 10-15

1.0

1438

2.37 x 10-15

1.0

1403

1.14 x 10-15

1.0

1337

4.1 x 10-16

1.5

1521

1.03 x 10-14

1.5

1438

2.60 x 10-15

1.5

1403

1.89 x 10-15

1.5

1337

5.6 x 10-16

2.0

1521

1.24 x 10-14

2.0

1438

3.07 x 10-15

2.0

1403

2.55 x 10-15

2.0

1337

1.01 x 10-15