New evidence for the dual origin of anomalous eutectic structures in undercooled Ni–Sn alloys: In situ observations and EBSD characterization
Yang, C. and Gao, J. and Zhang, Y. K. and Kolbe, M. and Herlach, D. M. (2011) New evidence for the dual origin of anomalous eutectic structures in undercooled Ni–Sn alloys: In situ observations and EBSD characterization. Acta Materialia, 59, pp. 3915-3926. Elsevier. DOI: 10.1016/j.actamat.2011.03.016. ISSN 1359-6454.
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Rapid solidification processes of glass-fluxed Ni81.3Sn18.7 eutectic alloys at various undercoolings were observed in situ using a highspeed camera. The microstructure of the samples was characterized using optical microscopy, scanning electron microscopy and electron back-scattering diffraction analysis. It was found that the recalescence front sweeps the sample surface from one side to the other, which coincides with the formation of a directional solidification microstructure. Such a finding suggests that it is feasible to measure crystal growth velocities in the undercooled liquid by tracking the loci of the recalescence front. The measured data show sudden acceleration of crystal growth kinetics at a medium undercooling, giving evidence for a transition from coupled growth to uncoupled growth. Microscopic studies revealed that the sample with an undercooling of 202 K comprises two types of anomalous eutectic, which are distinguished by the size and orientations of Ni-rich grains. The results verify a recent hypothesis that anomalous eutectic in undercooled Ni–Sn alloys has a dual origin: it results from eutectic dendrites growing at low undercoolings and from single-phase Ni-rich dendrites growing at high undercoolings.
|Title:||New evidence for the dual origin of anomalous eutectic structures in undercooled Ni–Sn alloys: In situ observations and EBSD characterization|
|Journal or Publication Title:||Acta Materialia|
|In Open Access:||No|
|In ISI Web of Science:||Yes|
|Page Range:||pp. 3915-3926|
|Keywords:||eutectic alloys, undercooling, anomalous eutectic, in situ observations, EBSD|
|HGF - Research field:||Aeronautics, Space and Transport|
|HGF - Program:||Space|
|HGF - Program Themes:||W FR - Forschung unter Weltraumbedingungen|
|DLR - Research area:||Space|
|DLR - Program:||W FR - Forschung unter Weltraumbedingungen|
|DLR - Research theme (Project):||W - Vorhaben Materialforschung unter Mikro-g (old)|
|Institutes and Institutions:||Institute of Materials Physics in Space|
|Deposited By:||Matthias Kolbe|
|Deposited On:||03 May 2011 08:27|
|Last Modified:||26 Mar 2013 13:28|
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