Disappearance of Ni3Nb primary phase in hypereutectic alloy of Ni-24.19wt% Nb at abruptly decreasing growth rate under directional solidification

Shuang Ming Li, Bing Lun Jiang, Bo Le Ma, Lin Liu, Heng Zhi Fu

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Directionally solidified microstructures of Ni-24.19wt% Nb hypereutectic alloy were investigated at the growth rate of 10 μm/s, and the abruptly decreasing growth rate from 10 to 1 μm/s. The results show that the microstructure consists of Ni3Nb primary phase and eutectic (Ni + Ni3Nb), in agreement with the theoretical calculation results at the growth rate of 10 μm/s. After the solidified distance of 20 mm, the growth of Ni3Nb primary phase achieves the quasi-steady state. At the abruptly decreasing growth rate from 10 to 1 μm/s, the volume fraction of Ni, Nb primary phase firstly increases, attributing to the change of interface composition, and then decreases to zero. Finally, the off-coupled growth microstructure changes to the coupled growth eutectic due to the competitive growth of interface temperature between Ni3Nb primary phase and eutectic (Ni + Ni3Nb). The disappearance of Ni3Nb primary phase does not simultaneously occur and mainly originates from the side to the center of the sample.

Original languageEnglish
Pages (from-to)35-40
Number of pages6
JournalHangkong Cailiao Xuebao/Journal of Aeronautical Materials
Volume26
Issue number3
StatePublished - Jun 2006

Keywords

  • Competitive growth
  • Directional solidification
  • Ni-Nb eutectic alloy

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