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On the Grain Boundary Diffusion of Ni into γ-Fe

1977; Japan Institute of Metals and Materials; Volume: 41; Issue: 12 Linguagem: Inglês

10.2320/jinstmet1952.41.12_1211

1880-6880

Yuko Hanatate, Mitsumasa Yamamoto, Hiroyasu Mitani,

Intermetallics and Advanced Alloy Properties

It has been confirmed previously by the authors that the presence of Ni in the grain boundaries plays an important role in the activated sintering for Fe-Ni powder compacts. However, the grain boundary diffusion of Ni into Fe has not been clarified. In this work, the grain boundary diffusion coefficient of 63Ni in bulk Fe is determined by the use of the residual-activity sectioning method in the temperature range from 1153 to 1287°C. The data obtained are analysed by the theory of grain boundary diffusion based on the instantaneous source model proposed by Suzuoka.The results are expressed as follows:Volume diffusion: D=1.09exp(−70900⁄RT) cm2/sec.Grain boundary diffusion: D′=24.1exp(−42100⁄RT) cm2/sec.The Fe-Ni mixed powder compacts at high temperatures are also observed by the use of an electron probe microanalyser, and the observed highly promoted grain boundary diffusion of Ni is confirmed to contribute to the Fe-Ni alloying in the inner part of Fe powder.