Haque, N, Cochrane, RF and Mullis, AM (2016) Rapid solidification morphologies in Ni3Ge: Spherulites, dendrites and dense-branched fractal structures. Intermetallics, 76. pp. 70-77. ISSN 0966-9795
Abstract
Single-phase β-Ni3Ge has been rapidly solidified via drop-tube processing. At low cooling rates (850–300 μm diameter particles, 700–2800 K s−1) the dominant solidification morphology, revealed after etching, is that of isolated spherulites in an otherwise featureless matrix. At higher cooling rates (300–75 μm diameter particles, 2800–25,000 K s−1) the dominant solidification morphology is that of dendrites, again imbedded within a featureless matrix. As the cooling rate increases towards the higher end of this range the dendrites display non-orthogonal side-branching and tip splitting. At the highest cooling rates studied (<75 μm diameter particles, >25,000 K s−1), dense-branched fractal structures are observed. Selected area diffraction analysis in the TEM reveals the spherulites and dendrites are a disordered variant of β-Ni3Ge, whilst the featureless matrix is the ordered variant of the same compound. We postulate that the spherulites and dendrites are the rapid solidification morphology and that the ordered, featureless matrix grew more slowly post-recalescence. Spherulites are most likely the result of kinetically limited growth, switching to thermal dendrites as the growth velocity increases. It is extremely uncommon to observe such a wide range of morphologies as a function of cooling rate in a single material.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2016, Elsevier Ltd. This is an author produced version of a paper published in Intermetallics. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Intermetallics; Phase transformation; Rapid solidification; Disordered trapping; Spherulites |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Chemical & Process Engineering (Leeds) > Institute for Materials Research (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 18 Jul 2016 09:09 |
Last Modified: | 18 Jul 2017 05:36 |
Published Version: | http://dx.doi.org/10.1016/j.intermet.2016.06.012 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.intermet.2016.06.012 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:102460 |