EBSD: a powerful microstructure analysis technique in the field of solidification.
This paper presents a few examples of the application of electron back-scatter diffraction (EBSD) to solidification problems. For directionally solidified Al-Zn samples, this technique could reveal the change in dendrite growth directions from <100> to <110> as the composition of zinc increases from 5 to 90 wt%. The corresponding texture evolution and grain selection mechanisms were also examined. Twinned dendrites that form under certain solidification conditions in Al-X specimens (with X = Zn, Mg, Ni, Cu) were clearly identified as <110> dendrite trunks split in their centre by a (111) twin plane. In Zn-0.2 wt% Al hot-dip galvanized coatings on steel sheets, EBSD clearly revealed the preferential basal orientation distribution of the nuclei as well as the reinforcement of this distribution by the faster growth of <1010> dendrites. Moreover, in Al-Zn-Si coatings, misorientations as large as 10 degrees mm(-1) have been measured within individual grains. Finally, the complex band and lamellae microstructures that form in the Cu-Sn peritectic system at low growth rate could be shown to constitute a continuous network initiated from a single nucleus. EBSD also showed that the alpha and beta phases had a Kurdjumov-Sachs crystallographic relationship.
Boehm-Courjault
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Computational Materials Laboratory, Ecole Polytechnique Fédérale de Lausanne, STI-IMX-LSMX, Station 12, CH-1015 Lausanne, Switzerland. emmanuelle.boehm@epfl.ch
Gonzales
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Jacot
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Kohler
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Mariaux
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Niederberger
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Salgado-Ordorica
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Rappaz
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