Analytical electron microscopy was used to determine the solute concentration profiles that were left behind the moving reaction front of a discontinuous precipitation reaction in a Ni-4at%Sn alloy. These profiles were converted into grain-boundary diffusivity values by using Cahn's diffusion equation, and data on the growth rate of the discontinuous precipitates. Such a procedure was applied for the first time to the Ni-Sn system, and it provided diffusivity data (table 17) which were very similar to published values for stationary grain boundaries.

Diffusion along the Moving Reaction Front of Discontinuous Precipitates in Ni-4at%Sn Alloy. P.Zieba, W.Gust: Materials Science Forum, 1999, 294-296, 145-8

 

 

Table 17

Grain Boundary Diffusivities in Ni-4at%Sn,

Deduced from Lamellar Precipitate Growth at 775K

 

Width (nm)

V (m/s)

Sn (at%)

sdD (m3/s)

250

1.1 x 10-9

1.10

1.8 x 10-23

170

4.3 x 10-9

0.95

4.5 x 10-23

200

7.2 x 10-9

1.02

1.2 x 10-22

280

9.3 x 10-10

0.98

1.7 x 10-23

300

3.2 x 10-9

1.01

6.2 x 10-23

270

1.3 x 10-9

0.91

2.1 x 10-23

350

4.3 x 10-9

1.07

9.1 x 10-24

320

2.8 x 10-9

0.90

6.6 x 10-23

400

2.3 x 10-10

0.97

5.8 x 10-23

320

5.1 x 10-10

1.06

1.1 x 10-23