The interdiffusion coefficients in the face-centered cubic -phase of this system were determined under pressures ranging from 0.101 to 3000MPa, and at temperatures ranging from 793 to 853K (table 26). It was found that the direct and indirect interdiffusion coefficients were positive. The diffusion coefficients decreased with increasing pressure. The activation energies for interdiffusion and impurity diffusion increased with pressure (table 27). The ratios of the activation volumes to the molar volume of Al were between 1.01 and 1.08. It was concluded that the diffusion of Cu and Mg in these alloys occurred mainly via a mono-vacancy mechanism.
T.Takahashi, A.Takahashi, H.Araki, T.Tanaka, Y.Minamino, Y.Miyamoto, Y.Yamane: Journal of the Japan Institute of Metals, 1994, 58[12], 1364-71
Table 26
Interdiffusion in the Al-Cu-Mg System
as a Function of Temperature and Pressure
Pressure (MPa) | Temperature (K) | Coefficient | Value (m2/s) |
0.101 | 793 | DCuCuAl | 9.5 x 10-14 |
0.101 | 793 | DCuMgAl | -1.4 x 10-15 |
0.101 | 793 | DMgCuAl | -2.9 x 10-14 |
0.101 | 793 | DMgMgAl | 2.7 x 10-13 |
0.101 | 813 | DCuCuAl | 1.1 x 10-13 |
0.101 | 813 | DCuMgAl | 4.6 x 10-14 |
0.101 | 813 | DMgCuAl | 1.5 x 10-14 |
0.101 | 813 | DMgMgAl | 3.7 x 10-13 |
0.101 | 833 | DCuCuAl | 2.3 x 10-13 |
0.101 | 833 | DCuMgAl | -1.4 x 10-14 |
0.101 | 833 | DMgCuAl | 1.2 x 10-13 |
0.101 | 833 | DMgMgAl | 5.6 x 10-13 |
0.101 | 853 | DCuCuAl | 3.6 x 10-13 |
0.101 | 853 | DCuMgAl | 5.2 x 10-14 |
0.101 | 853 | DMgCuAl | 8.1 x 10-14 |
0.101 | 853 | DMgMgAl | 1.1 x 10-12 |
1000 | 793 | DCuCuAl | 1.9 x 10-14 |
1000 | 793 | DCuMgAl | 2.9 x 10-13 |
1000 | 793 | DMgCuAl | -3.8 x 10-15 |
1000 | 793 | DMgMgAl | 5.7 x 10-14 |
1000 | 813 | DCuCuAl | 2.5 x 10-14 |
1000 | 813 | DCuMgAl | 3.5 x 10-15 |
1000 | 813 | DMgCuAl | -2.1 x 10-15 |
1000 | 813 | DMgMgAl | 8.0 x 10-14 |
1000 | 833 | DCuCuAl | 4.6 x 10-14 |
1000 | 833 | DCuMgAl | 3.0 x 10-15 |
1000 | 833 | DMgCuAl | 9.3 x 10-15 |
1000 | 833 | DMgMgAl | 1.3 x 10-13 |
1000 | 853 | DCuCuAl | 8.2 x 10-14 |
1000 | 853 | DCuMgAl | -4.8 x 10-15 |
1000 | 853 | DMgCuAl | -6.0 x 10-16 |
1000 | 853 | DMgMgAl | 2.5 x 10-13 |
2000 | 793 | DCuCuAl | 4.0 x 10-15 |
2000 | 793 | DCuMgAl | 1.0 x 10-17 |
2000 | 793 | DMgCuAl | 4.0 x 10-16 |
2000 | 793 | DMgMgAl | 1.2 x 10-14 |
2000 | 813 | DCuCuAl | 5.0 x 10-15 |
2000 | 813 | DCuMgAl | 6.0 x 10-16 |
2000 | 813 | DMgCuAl | 1.2 x 10-15 |
2000 | 813 | DMgMgAl | 1.7 x 10-14 |
2000 | 833 | DCuCuAl | 9.0 x 10-15 |
2000 | 833 | DCuMgAl | -1.4 x 10-15 |
2000 | 833 | DMgCuAl | -4.0 x 10-16 |
2000 | 833 | DMgMgAl | 2.9 x 10-14 |
2000 | 853 | DCuCuAl | 1.8 x 10-14 |
2000 | 853 | DCuMgAl | -4.0 x 10-15 |
2000 | 853 | DMgCuAl | -7.6 x 10-15 |
2000 | 853 | DMgMgAl | 5.6 x 10-14 |
3000 | 813 | DCuCuAl | 1.3 x 10-15 |
3000 | 813 | DCuMgAl | 2.7 x 10-16 |
3000 | 813 | DMgCuAl | -1.1 x 10-16 |
3000 | 813 | DMgMgAl | 3.8 x 10-15 |
3000 | 833 | DCuCuAl | 2.1 x 10-15 |
3000 | 833 | DCuMgAl | -3.3 x 10-16 |
3000 | 833 | DMgCuAl | -2.6 x 10-16 |
3000 | 833 | DMgMgAl | 6.6 x 10-15 |
3000 | 853 | DMgMgAl | 1.3 x 10-14 |
Table 27
Diffusion Parameters for the Al-Cu-Mg System
Pressure (MPa) | Do (m2/s) | Activation Energy | Value (kJ/mol) |
0.101 | 4.2 x 10-5 | QCuCu | 132 |
1000 | 1.9 x 10-5 | QCuCu | 137 |
2000 | 9.0 x 10-6 | QCuCu | 143 |
3000 | 5.0 x 10-6 | QCuCu | 149 |
0.101 | 6.9 x 10-5 | QMgMg | 128 |
1000 | 4.9 x 10-5 | QMgMg | 136 |
2000 | 3.4 x 10-5 | QMgMg | 144 |
3000 | 2.4 x 10-5 | QMgMg | 152 |
0.101 | 2.1 x 10-5 | QMg(Al-Cu) | 120 |
1000 | 2.7 x 10-5 | QMg(Al-Cu) | 133 |
2000 | 3.5 x 10-5 | QMg(Al-Cu) | 144 |
3000 | 4.4 x 10-5 | QMg(Al-Cu) | 157 |