The bulk diffusivity of Cu in the superalloy was studied at between 1050 and 1500K by using the serial sectioning technique. It was found that the results (table 169) could be described by:

D (m2/s) = 5.02 x 10-5 exp[-269.05(kJ/mol)/RT]

Grain-boundary diffusion of the tracer in small-grained samples was studied at between 760 and 1170K. It was found that the results could be described by:

D (m2/s) = 3.35 x 10-5 exp[-170.80(kJ/mol)/RT]

A.R.Paul, M.C.Naik, K.N.G.Kaimal: Physica Status Solidi A, 1991, 128[1], 9-19

Table 165

Diffusion Coefficients for 57Ni in Fe-20Ni-15at%Cr

Temperature (C) | Atmosphere/Grain Size | D (cm2/s) |

1400 | He/fine | 6.93 x 10-10 |

1363 | He/fine | 4.35 x 10-10 |

1244 | Ar/fine | 5.30 x 10-11 |

1168 | vacuum/fine | 2.50 x 10-11 |

1108 | Ar/fine | 5.78 x 10-12 |

1068 | He/coarse | 4.99 x 10-12 |

963 | vacuum/coarse | 2.92 x 10-13 |

Table 166

Tracer Diffusion Coefficient, DNi, in the Fe-Ni-Cr System at 1223K

Ni (wt%) | Cr (wt%) | Value(m2/s) |

70 | 18 | 6.1 x 10-14 |

71 | 20 | 5.0 x 10-14 |

72 | 21 | 4.3 x 10-14 |

67 | 12 | 1.36 x 10-13 |

54 | 24 | 5.5 x 10-14 |

85 | 9 | 2.03 x 10-13 |

85 | 11 | 1.51 x 10-13 |

84 | 13 | 6.6 x 10-14 |

30 | 26 | 1.34 x 10-13 |

58 | 24 | 1.18 x 10-13 |

75 | 24 | 7.5 x 10-14 |

50 | 15 | 3.0 x 10-15 |

45 | 28 | 6.6 x 10-14 |

57 | 29 | 4.19 x 10-13 |

35 | 19 | 2.91 x 10-13 |

42 | 30 | 1.50 x 10-13 |