The first systematic investigation was made here of the pressure and orientation dependences of grain boundary diffusion. The diffusion of Zn was measured at 553K, in the B-kinetic regime, using various sets of bicrystals and pressures of up to 1.2GPa. Symmetrical <001>, <011> and <111> tilt boundaries were studied (tables 1 to 3), with tilt angles that corresponded to a low coincidence lattice-site parameter. The Zn depth profiles were measured by means of electron probe micro-analysis, and were analyzed by using the Whipple equation. The orientation dependence of the diffusivity went through minima, for the high-coincidence grain boundaries, under all of the applied pressures. The activation volume ranged from 26 to 47% of the atomic volume of Al, and exhibited slight maxima for the high-coincidence grain boundaries.
Diffusion of Zn along Tilt Grain Boundaries in Al - Pressure and Orientation Dependence. P.Klugkist, A.N.Aleshin, W.Lojkowski, L.S.Shvindlerman, W.Gust, E.J.Mittemeijer: Acta Materialia, 2001, 49[15], 2941-9
Table 1
Triple Product at 553K for Zn Diffusion through Tilt Grain Boundaries in Al
Tilt Axis: <001>
Tilt Angle (º) | Pressure (MPa) | sδD (m3/s) |
33 | 0.1 | 1.25 x 10-19 |
33 | 0.4 | 1.39 x 10-19 |
33 | 300 | 1.14 x 10-19 |
33 | 600 | 4.9 x 10-20 |
33 | 900 | 8.8 x 10-20 |
33 | 1200 | 7.4 x 10-20 |
36 | 0.1 | 1.17 x 10-19 |
36 | 0.4 | 1.03 x 10-19 |
36 | 300 | 1.12 x 10-19 |
36 | 900 | 5.2 x 10-20 |
36 | 1200 | 4.4 x 10-20 |
36.8 | 0.1 | 8.1 x 10-20 |
36.8 | 0.4 | 8.0 x 10-20 |
36.8 | 300 | 7.5 x 10-20 |
36.8 | 600 | 3.7 x 10-20 |
36.8 | 900 | 4.2 x 10-20 |
36.8 | 1200 | 3.0 x 10-20 |
39 | 0.1 | 8.5 x 10-20 |
39 | 0.4 | 8.5 x 10-20 |
39 | 300 | 7.0 x 10-20 |
39 | 600 | 4.2 x 10-20 |
39 | 900 | 5.0 x 10-20 |
39 | 1200 | 3.2 x 10-20 |
42.5 | 0.1 | 8.7 x 10-20 |
42.5 | 0.4 | 8.2 x 10-20 |
42.5 | 300 | 9.1 x 10-20 |
42.5 | 900 | 4.4 x 10-20 |
42.5 | 1200 | 4.2 x 10-20 |
Table 2
Triple Product at 553K for Zn Diffusion through Tilt Grain Boundaries in Al
Tilt Axis: <011>
Tilt Angle (º) | Pressure (MPa) | sδD (m3/s) |
35 | 0.1 | 2.1 x 10-20 |
35 | 0.4 | 1.9 x 10-20 |
35 | 300 | 1.8 x 10-20 |
35 | 600 | 1.2 x 10-20 |
35 | 900 | 9.3 x 10-21 |
35 | 1200 | 8.9 x 10-21 |
38.5 | 0.1 | 8.9 x 10-21 |
38.5 | 0.4 | 7.4 x 10-21 |
38.5 | 300 | 7.1 x 10-21 |
38.5 | 600 | 6.6 x 10-21 |
38.5 | 900 | 4.4 x 10-21 |
38.5 | 1200 | 2.4 x 10-21 |
46 | 0.1 | 5.6 x 10-20 |
46 | 0.4 | 6.8 x 10-20 |
46 | 300 | 4.2 x 10-20 |
46 | 600 | 2.2 x 10-20 |
46 | 900 | 2.6 x 10-20 |
46 | 1200 | 2.3 x 10-20 |
Table 3
Triple Product at 553K for Zn Diffusion through Tilt Grain Boundaries in Al
Tilt Axis: <111>
Tilt Angle (º) | Pressure (MPa) | sδD (m3/s) |
38 | 0.1 | 1.85 x 10-20 |
38 | 0.4 | 1.9 x 10-20 |
38 | 600 | 9.4 x 10-21 |
38 | 1200 | 5.5 x 10-21 |
39 | 0.1 | 2.35 x 10-20 |
39 | 0.4 | 3.3 x 10-20 |
39 | 300 | 1.3 x 10-20 |
39 | 600 | 1.3 x 10-20 |
39 | 900 | 1.1 x 10-20 |
39 | 1200 | 1.1 x 10-20 |
43 | 0.1 | 2.15 x 10-20 |
43 | 0.4 | 3.41 x 10-20 |
43 | 300 | 1.7 x 10-20 |
43 | 600 | 1.8 x 10-20 |
43 | 900 | 1.8 x 10-20 |
43 | 1200 | 8.6 x 10-21 |