Evidence that the liquid structure affects the nucleation of the primary metastable L12-Al3Zr in additive manufacturing

The strategy aiming at promoting the precipitation of the primary metastable L12-Al3X phase is the most widely used to refine grain size in Al alloys designed for additive manufacturing. It is generally admitted that Al grains nucleate onto the primary L12-Al3X precipitates by epitaxy resulting in a...

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Bibliographic Details
Published in:Scripta materialia 2023-03, Vol.226, p.115212, Article 115212
Main Authors: Buttard, Maxence, Martin, Guilhem, Harrison, Patrick, Rauch, Edgar F., Chéhab, Béchir, Jarry, Philippe, Blandin, Jean-Jacques, Donnadieu, Patricia
Format: Article
Language:English
Subjects:
Additive manufacturing
Al alloys
Engineering Sciences
ISRO
Materials
Nucleation
Primary phase
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Summary:The strategy aiming at promoting the precipitation of the primary metastable L12-Al3X phase is the most widely used to refine grain size in Al alloys designed for additive manufacturing. It is generally admitted that Al grains nucleate onto the primary L12-Al3X precipitates by epitaxy resulting in a cube-cube orientation relationship. Here we report TEM observations showing clusters of precipitates of this primary L12-Al3X phase. Using Automated Crystallographic Orientation Mapping in the TEM, we show that such clusters consist of various orientations. Analysis of those clusters reveals that some orientations share common 5-fold rotational symmetry axes suggesting that they have nucleated from an icosahedral template. We conclude that Icosahedral Short Range Order (ISRO) in the liquid can play a role in the nucleation of the primary metastable L12-Al3Zr phase through the ISRO-mediated nucleation mechanism. [Display omitted]
ISSN:1359-6462
1872-8456
DOI:10.1016/j.scriptamat.2022.115212