The technique of H introduction by mechanical abrasion was applied to the determination of H diffusivity, in high-purity Al and Al-1000ppm[at]Si dilute alloy, by coupling it with thermal evolution spectroscopy. The diffusion data for high-purity Al could be described by:

D (m2/s) = 3.0 x 10-6 exp[-30(kJ/mol)/RT]

The diffusivities were larger than those previously reported. It was suggested that the interstitial mechanism predominated for H diffusion in high-purity Al; even in the low temperature region. Similar measurements were performed on Al-1000ppm[at]Si dilute alloy. By means of the trapping-detrapping model, the binding energy of a H atom to a Si atom was estimated to be 16kJ/mol. This showed that Si atoms in Al served as weak trapping centers.

S.Hayashi: Japanese Journal of Applied Physics - 1, 1998, 37[3A], 930-7

 

Table 21

Diffusivity of H in Pure 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

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

 

Table 22

Diffusivity of H in Liquid Al

 

Temperature (K)

D (cm2/s)

1053

4.16 x 10-3

1079

4.37 x 10-3

1110

4.40 x 10-3

1122

4.57 x 10-3

1148

4.66 x 10-3

1203

5.62 x 10-3

1203

5.44 x 10-3

1274

5.88 x 10-3