In situ investigation of unidirectional solidification in Sn-0.7Cu and Sn-0.7Cu-0.06Ni

C. M. Gourlay, K. Nogita, A. K. Dahle, Y. Yamamoto, K. Uesugi, T. Nagira, M. Yoshiya, H. Yasuda

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56 Citations (Scopus)


The dynamics of off-eutectic solidification are studied in two Pb-free solders using synchrotron X-ray radiography and post mortem scanning electron microscopy. The early stages of growth revealed the onset of coupled growth and phase competition. In Sn-0.7 wt.% Cu, the βSn-Cu6Sn5 eutectic then grew with Cu6Sn5 rods leading the βSn phase, with a range of rod spacings and local interface curvatures. However, these nonfaceted-faceted eutectic features were exhibited much more weakly than in the Al-Si and Fe-C eutectics, despite primary Cu6Sn5 crystals exhibiting marked faceting. In Sn-0.7 wt.% Cu-0.06 wt.% Ni, primary intermetallic laths grew ahead of a rod-like βSn-(Cu,Ni)6Sn 5 univariant eutectic front. The univariant eutectic had a narrow freezing range and a similar spacing to the invariant eutectic at the same velocity. Composition measurements suggest that the univariant eutectic groove descends in the direction of the Sn + Cu6Sn5 binary eutectic point.

Original languageEnglish
Pages (from-to)4043-4054
Number of pages12
JournalActa Materialia
Issue number10
Publication statusPublished - Jun 2011
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys


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