Different grain morphologies in grain-refined 7075 billet
Authors: Eskin, D.G.1; Ruvalcaba, D.1; Kwakernaak, C.2; Katgerman, L.2
Source: Materials Science and Technology, Volume 25, Number 10, October 2009 , pp. 1175-1182(8)
Publisher: Maney Publishing
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Abstract:
Different grain morphologies are identified in the central portion of a direct-chill cast, grain-refined 7075-alloy billet, i.e. coarse-cell and fine-cell dendrite grains and grains that are less developed than the bulk of the structure. Three-dimensional reconstruction of a representative volume is used for separating these distinct grain types. Microsegregation measurements show that coarse-cell grains are depleted of solutes (Cu, Mg, Zn), whereas fine-cell grains and less developed grains are enriched in solutes. Analysis of non-equilibrium solidification demonstrates that the observed grain types could be formed in different stages of solidification and correspondingly in different parts of the billet sump. Coarse-cell grains nucleate in the upper part of the sump, whereas fine-cell grains and less developed grains originate from deeper portions of the sump.Keywords: MICROSEGREGATION; THREE-DIMENSIONAL RECONSTRUCTION; GRAIN MORPHOLOGY; MACROSEGREGATION
Document Type: Research article
DOI: 10.1179/174328408X374630
Affiliations: 1: Materials Innovation Institute, Mekelweg 2, 2628CD Delft, The Netherlands 2: Delft University of Technology, Dept. Materials Science and Engineering, Mekelweg 2, 2628CD Delft, The Netherlands
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