The diffusivities of O in liquid Sn at temperatures of between 800 and 900C, and in the liquid alloy at 900C, were measured by using a modified coulometric titration method and a galvanic cell of the form:

O in liquid sample || yttria-stabilized zirconia || air, Pt

It was found that the diffusion coefficient of O in liquid Sn was independent of the O concentration (table 18), and could be described by:

D(cm2/s) = 0.003421 exp[-33.954(kJ/g-atom)/RT]

These data were in agreement with previous results. In the case of the Cu-Ba alloy, it was observed that the O diffusivity depended upon the O concentration and ranged from 0.000295cm2/s at an O concentration of 0.00244at%, to 0.000862cm2/s at an O concentration of 0.00007at% (table 19). The decrease in O diffusivity with increasing O concentration was attributed to an enhanced configurational structural order in the Ba-Cu alloy melt, due to the strong affinity between Ba and O atoms.

H.Chou, T.C.Chow, S.F.Tsay, H.S.Chen: Journal of the Electrochemical Society, 1995, 142[6], 1814-9

 

 

Table 18

Diffusivity of O in Liquid Sn

 

 

Temperature (C)

 

O (at%)

 

D (cm2/s)

 

 

800

 

0.011568

 

7.47 x 10-5

800

0.006073

7.37 x 10-5

800

0.002074

7.59 x 10-5

800

0.000709

7.58 x 10-5

800

0.000242

7.42 x 10-5

850

0.012049

8.76 x 10-5

850

0.006471

9.56 x 10-5

850

0.002296

9.22 x 10-5

850

0.000815

9.41 x 10-5

900

0.012688

1.04 x 10-4

900

0.007118

1.03 x 10-4

900

0.002717

1.03 x 10-4

900

0.001036

1.07 x 10-4

900

0.000395

1.05 x 10-4

 

 

 

 

Table 19

Diffusivity of O in Liquid Cu0.65Ba0.35 at 900C

 

 

C (at%)

 

D (cm2/s)

 

 

0.00244

 

2.953 x 10-4

0.00194

3.734 x 10-4

0.00152

3.337 x 10-4

0.001077

4.595 x 10-4

0.000972

4.511 x 10-4

0.000331

4.574 x 10-4

0.000252

5.571 x 10-4

0.000204

6.225 x 10-4

0.000167

6.46 x 10-4

0.000128

7.267 x 10-4

0.000105

7.734 x 10-4

0.00007

8.623 x 10-4