Interdiffusion in single-phase couples was investigated at temperatures ranging from 1118 to 1583K (tables 31 and 32). The concentration distributions after annealing were determined by means of electron-probe micro-analysis. The interdiffusion coefficients were then calculated by using the Boltzmann-Matano method. No significant concentration dependence of interdiffusion was detected in either compound. The diffusivities could be described by relationships of the form:

TiAl:      D (m2/s) = 0.00028 exp[-295(kJ/mol)/RT]

Ti3Al:      D (m2/s) = 0.001 exp[-312(kJ/mol)/RT]

W.Sprengel, H.Nakajima, H.Oikawa: Materials Science and Engineering A, 1996, 213[1-2], 45-50

 

 

 

Table 31

Interdiffusion in TiAl

 

 

Temperature (K)

 

D (m2/s)

 

 

1116

 

6.35 x 10-18

1165

1.09 x 10-17

1270

2.08 x 10-16

1270

2.85 x 10-16

1276

1.57 x 10-16

1371

1.54 x 10-15

1473

1.27 x 10-14

1473

1.10 x 10-14

1489

1.49 x 10-14

1583

3.92 x 10-14

 

 

 

 

 

Table 32

Interdiffusion in Ti3Al

 

 

Temperature (K)

 

D (m2/s)

 

 

1171

 

1.2 x 10-17

1273

1.9 x 10-16

1327

5.3 x 10-16

1374

1.5 x 10-15

1404

2.8 x 10-15