An investigation was made of the effect of the Fe content upon Fe diffusion. A comparison was also made of the effect of the Fe concentration upon Fe diffusion in -type and -type alloys. It was concluded that Mössbauer spectroscopy was a useful method for clarifying microscopic diffusion mechanisms with regard to the jump frequencies of diffusing atoms. By taking account of Mössbauer data, a suppression of Fe diffusion (tables 33 and 34) could be attributed to the occurrence of a short-range ordering of Fe atoms. This ordering, which was perhaps of B2-type, led to a decrease in the number of diffusion paths for Fe atoms; thus producing a lower diffusivity.

H.Nakajima, S.Ohshida, K.Nonaka, Y.Yoshida, F.E.Fujita: Scripta Materialia, 1996, 34[6], 949-53

 

 

 

Table 33

Diffusion of Fe in -Ti-Fe Alloys

 

 

Material

 

Temperature (K)

 

D (m2/s)

 

 

Ti

 

1176

 

7.28 x 10-13

Ti

1270

2.66 x 10-12

Ti

1344

5.41 x 10-12

Ti-1Fe

1176

7.44 x 10-13

Ti-1Fe

1270

2.11 x 10-12

Ti-1Fe

1344

4.56 x 10-12

Ti-5Fe

1176

3.85 x 10-13

Ti-5Fe

1270

1.55 x 10-12

Ti-5Fe

1344

3.60 x 10-12

Ti-13Fe

1176

1.39 x 10-13

Ti-13Fe

1270

7.10 x 10-13

Ti-13Fe

1344

2.83 x 10-12

 

 

 

 

Table 34

Arrhenius Parameters for Fe Diffusion

in -Ti and Ti-Fe Alloys at 1176 to 1344

 

 

Material

 

Do (m2/s)

 

Q (kJ/mol)

 

 

Ti

 

7.8 x 10-6

 

157.9

Ti-1Fe

1.4 x 10-6

141.5

Ti-5Fe

2.5 x 10-5

175.5

Ti-13Fe

3.4 x 10-3

234.3