Grain boundary segregation in binary nickel-bismuth alloy

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• 作者：M.R. Chellali^a ; ^b ; ^c ; ^{m_chel01@uni-muenster.de" class="auth_mail" title="E-mail the corresponding author} ; L. Zheng^c ; ^d ; R. Schlesiger^c ; B. Bakhti^e ; A. Hamou^b ; J. Janovec^a ; G. Schmitz^f
• 关键词：Nickel ; Bismuth ; Grain-boundary segregation ; Embrittlement ; Atom probe tomography ; Nanocrystalline alloys
• 刊名：Acta Materialia
• 出版年：2016
• 出版时间：15 January 2016
• 年：2016
• 卷：103
• 期：Complete
• 页码：754-760
• 全文大小：1732 K

文摘

Grain boundary segregation and segregation kinetics are investigated by means of atom probe tomography in a binary Nanocrystalline nickel-bismuth alloy. Gibbsian excess and width of segregation layers at grain boundary are quantitatively determined. If segregation is approximated by McLean kinetics, remarkably fast volume transport of bismuth is derived. However, details of the segregation kinetics are in significant contrast to the McLean model. Additional influence of attractive Bismuth interaction is indicated. The experimentally demonstrated clear segregation tendency suggests that reported embrittlement of Ni–Bi alloys is due to significant grain boundary segregation of Bi. Diffusivity of Bi in nanocrystalline Ni and segregation amplitude were found to beD_B≈(2.16±0.48)×10⁻²¹ m²s−1$D_B\approx \left(2.16\pm 0.48\right)\times {10}^{-21}{\mathrm{m}}^2{\mathrm{s}}^{-1}$, and 17 respectively.