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 37 to 39), 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.
P.Klugkist, A.N.Aleshin, W.Lojkowski, L.S.Shvindlerman, W.Gust, E.J.Mittemeijer: Acta Materialia, 2001, 49[15], 2941-9Table 37
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 |
continued
Table 37 (continued)
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 | 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 |