The H diffusivity was determined, at temperatures ranging from 446 to 681K (table 30), by using a glow discharge permeation method which permitted the extension of the temperature range of measurements by enhancing the permeation flux; in spite of the small equilibrium solubility of H in solid Al. The diffusivity exhibited a linear Arrhenius behavior, with a pre-exponential factor of 6.1 x 10-5m2/s and an activation energy of 54.8kJ/mol. These values were higher than published estimates which had been based upon H evolution at high temperature. However, the present values were consistent with the results which had been obtained by using an electrolytic permeation method at almost room temperature. It was suggested that H atoms in Al diffused via the interstitial mechanism over the entire temperature range.

H.Saitoh, Y.Iijima, H.Tanaka: Acta Metallurgica et Materialia, 1994, 42[7], 2493-8

 

Table 30

Diffusivity of H in Al

 

Temperature (K)

D (m2/s)

446

2.3 x 10-11

453

2.9 x 10-11

459

3.7 x 10-11

467

4.3 x 10-11

469

4.9 x 10-11

483

6.8 x 10-11

continued

Table 30 (continued)

Diffusivity of H in Al

 

Temperature (K)

D (m2/s)

494

9.5 x 10-11

503

1.3 x 10-10

517

1.7 x 10-10

523

2.2 x 10-10

531

2.9 x 10-10

535

2.9 x 10-10

540

3.2 x 10-10

549

4.0 x 10-10

560

4.7 x 10-10

579

7.2 x 10-10

583

6.8 x 10-10

592

8.7 x 10-10

613

1.2 x 10-9

619

1.3 x 10-9

624

1.6 x 10-9

647

2.0 x 10-9

655

2.9 x 10-9

681

4.3 x 10-9