Specimens of Fe-15Cr-15Ni-2Mo, Fe-20Cr-15Ni-2Mo, Fe-15Cr-20Ni-2Mo and Fe-20Cr-20Ni-2Mo were covered with a thin layer of 14C, and diffusion-annealed in sealed quartz tubes containing Zr getter at 650 to 1000C. The diffusion of C was affected by alloying with Cr and Ni (table 110): DC decreased in the presence of Cr, whereas the opposite effect was observed upon alloying with Ni:
Fe-15Cr-15Ni-2Mo: D (cm2/s) = 2.90 x 10-1 exp[-37.80(kcal/mol)/RT]
Fe-20Cr-15Ni-2Mo: D (cm2/s) = 1.06 x 100 exp[-41.10(kcal/mol)/RT]
Fe-15Cr-20Ni-2Mo: D (cm2/s) = 2.90 x 10-2 exp[-32.00(kcal/mol)/RT]
Fe-20Cr-20Ni-2Mo: D (cm2/s) = 2.68 x 100 exp[-43.00(kcal/mol)/RT]
The effect of combined additions of Cr and Ni was not additive, as the decrease in DC was more intense than in the presence of Cr alone.
L.V.Pavlinov: Fizika Metallov i Metallovedenie, 1976, 41[2], 344-50
Table 111
Diffusion of 59Fe in Fe-Cr-Ni-Mo Alloys
Alloy (wt%) | Temperature (C) | D (cm2/s) |
Fe-15Cr-15Ni-2Mo | 950 | 3.07 x 10-12 |
Fe-20Cr-15Ni-2Mo | 950 | 3.66 x 10-12 |
Fe-15Cr-20Ni-2Mo | 950 | 3.22 x 10-12 |
Fe-20Cr-20Ni-2Mo | 950 | 1.62 x 10-12 |
Fe-15Cr-15Ni-2Mo | 1000 | 3.98 x 10-12 |
Fe-20Cr-15Ni-2Mo | 1000 | 4.04 x 10-12 |
Fe-15Cr-20Ni-2Mo | 1000 | 6.04 x 10-12 |
Fe-20Cr-20Ni-2Mo | 1000 | 4.39 x 10-12 |
Fe-15Cr-15Ni-2Mo | 1050 | 9.87 x 10-12 |
Fe-20Cr-15Ni-2Mo | 1050 | 7.92 x 10-12 |
Fe-15Cr-20Ni-2Mo | 1050 | 8.87 x 10-12 |
Fe-20Cr-20Ni-2Mo | 1050 | 7.40 x 10-12 |
Fe-15Cr-15Ni-2Mo | 1100 | 2.83 x 10-11 |
Fe-20Cr-15Ni-2Mo | 1100 | 3.10 x 10-11 |
Fe-15Cr-20Ni-2Mo | 1100 | 6.01 x 10-11 |
Fe-20Cr-20Ni-2Mo | 1100 | 4.20 x 10-11 |
Fe-15Cr-15Ni-2Mo | 1200 | 8.66 x 10-11 |
Fe-20Cr-15Ni-2Mo | 1200 | 6.18 x 10-11 |
Fe-15Cr-20Ni-2Mo | 1200 | 8.13 x 10-11 |
Fe-20Cr-20Ni-2Mo | 1200 | 7.49 x 10-11 |
Fe-15Cr-15Ni-2Mo | 1250 | 4.63 x 10-10 |
Fe-20Cr-15Ni-2Mo | 1250 | 4.33 x 10-10 |
Fe-15Cr-20Ni-2Mo | 1250 | 4.95 x 10-10 |
Fe-20Cr-20Ni-2Mo | 1250 | 4.75 x 10-10 |
Table 112
Parameters for Mo Diffusion in Fe-Cr-Ni-Mo Alloys
Diffusion Sandwich | Do (m2/s) | E (kJ/mol) |
12Cr16Ni2Mo/12Cr16Ni | 3.65 x 10-5 | 265.2 |
18Cr16Ni2Mo/18Cr16Ni | 7.66 x 10-5 | 273.6 |
19Cr12Ni2Mo/19Cr12Ni | 1.39 x 10-4 | 281.2 |
12Cr16Ni2Mo/18Cr16Ni | 9.47 x 10-5 | 275.3 |
12Cr14Ni2Mo0.2N/12Cr16Ni0.2N | 1.98 x 10-5 | 257.6 |
19Cr16Ni2Mo0.27N/19Cr14Ni0.29N | 5.04 x 10-5 | 268.7 |
19Cr16Ni2Mo0.27N/19Cr12Ni0.25N | 6.55 x 10-5 | 271.7 |