It was recalled that the small size of the Cr atom, and its apparent ability to act as an interstitial, had led to speculation that Cr could appreciably affect irradiation damage recovery in Zr alloys. Previous work, which had indicated normal diffusion behavior for Cr in -Zr, had helped to form the view that diffusion in the latter was intrinsically normal. Here, an investigation was made in order to extend some earlier work on monocrystals, and to measure Cr diffusion parallel to, and perpendicular to, the c-axis. It was found that the Cr diffusion coefficients in -Zr monocrystals exhibited good Arrhenius behavior at temperatures of between 885 and 1120K. The diffusivities (table 373), their anisotropy (D > D), and their low activation energies, were consistent with the operation of a predominantly interstitial diffusion mechanism. The diffusion of Cr in the alloys was slower than in Zr.
G.M.Hood, R.J.Schultz: Journal of Nuclear Materials, 1993, 200[1], 141-3
Table 364
Diffusion of Hf in Zr-1at%Nb
Temperature (K) | D (m2/s) |
1101.8 | 1.81 x 10-19 |
999.0 | 6.98 x 10-21 |
934.8 | 9.15 x 10-22 |
840.5 | 2.33 x 10-23 |
Table 365
Diffusion of Hf in Zr-2.5at%Nb
Temperature (K) | D (m2/s) |
1101.8 | 1.47 x 10-19 |
999.0 | 7.48 x 10-21 |
934.8 | 4.24 x 10-22 |
840.5 | 1.91 x 10-23 |
Table 366
Parameters for Nb Diffusion in Zr-Nb Alloys
D = Doexp[-E/kT]exp[α(Tm/T)2]
Nb (at%) | Do (m2/s) | E (eV) | α |
0 | 7.1 x 10-5 | 3.83 | 4.1 |
5.5 | 2.1 x 10-4 | 3.55 | 3.77 |
16.3 | 1.7 x 10-4 | 3.18 | 2.4 |
28.1 | 6.5 x 10-5 | 3.09 | 1.96 |
Table 367
Parameters for Zr Diffusion in Zr-Nb Alloys
D = Doexp[-E/kT]exp[α(Tm/T)2]
Nb (at%) | Do (m2/s) | E (eV) | α |
0 | 4.77 x 10-5 | 3.32 | 3.81 |
5.5 | 4.4 x 10-5 | 3.26 | 3.72 |
16.3 | 2.53 x 10-5 | 2.84 | 2.30 |
28.1 | 1.3 x 10-5 | 2.71 | 1.62 |
Table 368
Parameters for Nb Diffusion in Zr-Nb Alloys
D = D1exp[-E1/kT] + D2exp[-E2/kT]
Nb (at%) | D1 (m2/s) | D2 (m2/s) | E1 (eV) | E2 (eV) |
0 | 2.8 x 10-6 | 2.7 x 10-10 | 2.11 | 0.99 |
5.5 | 9.8 x 10-4 | 1.4 x 10-8 | 3.13 | 1.36 |
16.3 | 5.0 x 10-6 | 3.8 x 10-11 | 2.17 | 0.98 |
28.1 | 9.6 x 10-6 | 1.7 x 10-8 | 2.44 | 1.70 |
Table 369
Parameters for Zr Diffusion in Zr-Nb Alloys
D = D1exp[-E1/kT] + D2exp[-E2/kT]
Nb (at%) | D1 (m2/s) | D2 (m2/s) | E1 (eV) | E2 (eV) |
0 | 3.7 x 10-7 | 2.5 x 10-11 | 1.75 | 0.60 |
5.5 | 2.2 x 10-4 | 2.6 x 10-9 | 2.88 | 1.09 |
16.3 | 1.7 x 10-6 | 1.2 x 10-9 | 1.99 | 1.18 |
28.1 | 1.5 x 10-6 | 2.35 x 10-10 | 2.07 | 1.21 |
Table 370
Isotope-Effect Parameter for Zr Diffusion in Zr-5.5at%Nb
Temperature (K) | IEP |
2003 | 0.383 |
1540 | 0.390 |
1352 | 0.380 |
1194 | 0.318 |
1178 | 0.335 |
Table 371
Bulk Diffusivity of 95Nb in Zr-Nb Alloys
Temperature (K) | Nb (at%) | D (m2/s) |
1035 | 16.3 | 7.48 x 10-16 |
1057 | 28.1 | 1.65 x 10-16 |
1091 | 16.3 | 1.74 x 10-15 |
continued
Table 371 (continued)
Temperature (K) | Nb (at%) | D (m2/s) |
1098 | 28.1 | 2.95 x 10-16 |
1146 | 16.3 | 3.12 x 10-15 |
1156 | 28.1 | 1.01 x 10-15 |
1178 | 5.5 | 1.73 x 10-14 |
1194 | 5.5 | 2.07 x 10-14 |
1203 | 5.5 | 1.99 x 10-14 |
1203 | 28.1 | 2.11 x 10-15 |
1218 | 16.3 | 8.27 x 10-15 |
1270 | 28.1 | 4.70 x 10-15 |
1287 | 5.5 | 5.84 x 10-14 |
1291 | 16.3 | 2.30 x 10-14 |
1324 | 28.1 | 1.06 x 10-14 |
1352 | 5.5 | 8.20 x 10-14 |
1374 | 16.3 | 6.44 x 10-14 |
1415 | 28.1 | 3.37 x 10-14 |
1456 | 16.3 | 1.75 x 10-13 |
1461 | 5.5 | 2.21 x 10-13 |
1502 | 28.1 | 1.10 x 10-13 |
1540 | 5.5 | 5.40 x 10-13 |
1545 | 16.3 | 4.31 x 10-13 |
1583 | 28.1 | 2.30 x 10-13 |
1685 | 5.5 | 1.29 x 10-12 |
1710 | 16.3 | 1.99 x 10-12 |
1725 | 28.1 | 9.07 x 10-13 |
1774 | 5.5 | 2.95 x 10-12 |
1802 | 5.5 | 3.31 x 10-12 |
1840 | 16.3 | 5.88 x 10-12 |
1853 | 28.1 | 2.66 x 10-12 |
1944 | 5.5 | 9.41 x 10-12 |
1957 | 5.5 | 1.23 x 10-11 |
2003 | 5.5 | 1.94 x 10-11 |
Table 372
Bulk Diffusivity of 95Zr in Zr-Nb Alloys
Temperature (K) | Nb (at%) | D (m2/s) |
994 | 16.3 | 1.38 x 10-15 |
1065 | 16.3 | 3.50 x 10-15 |
1113 | 5.5 | 3.16 x 10-14 |
1124 | 28.1 | 1.68 x 10-15 |
1136 | 16.3 | 9.52 x 10-15 |
1178 | 5.5 | 5.80 x 10-14 |
1194 | 5.5 | 6.08 x 10-14 |
1203 | 5.5 | 6.41 x 10-14 |
1202 | 28.1 | 5.97 x 10-15 |
1218 | 16.3 | 2.54 x 10-14 |
1287 | 5.5 | 1.65 x 10-13 |
1270 | 28.1 | 1.23 x 10-14 |
1291 | 16.3 | 5.61 x 10-14 |
1324 | 28.1 | 2.58 x 10-14 |
1352 | 5.5 | 2.10 x 10-13 |
1374 | 16.3 | 1.47 x 10-13 |
1415 | 28.1 | 7.87 x 10-14 |
1461 | 5.5 | 4.67 x 10-13 |
1456 | 16.3 | 3.45 x 10-13 |
1502 | 28.1 | 2.00 x 10-13 |
1540 | 5.5 | 9.97 x 10-13 |
1545 | 16.3 | 6.52 x 10-13 |
1583 | 28.1 | 4.44 x 10-13 |
1630 | 5.5 | 1.17 x 10-12 |
1685 | 5.5 | 1.98 x 10-12 |
1710 | 16.3 | 2.68 x 10-12 |
1725 | 28.1 | 1.42 x 10-12 |
1774 | 5.5 | 3.94 x 10-12 |
1802 | 5.5 | 4.34 x 10-12 |
continued
Table 372 (continued)
Bulk Diffusivity of 95Zr in Zr-Nb Alloys
Temperature (K) | Nb (at%) | D (m2/s) |
1840 | 16.3 | 6.92 x 10-12 |
1853 | 28.1 | 3.74 x 10-12 |
1944 | 5.5 | 1.02 x 10-11 |
1957 | 5.5 | 1.23 x 10-11 |
2003 | 5.5 | 1.87 x 10-11 |