Microstructure Solidification Maps for Al-10 Wt Pct Si Alloys

Hypo-eutectic Al-Si alloys are widely used in both the automotive and aerospace industries; however, they still have limited usage as structural materials, due to the inherent morphology of the Si phase that forms within the eutectic structure. This non-ideal Si morphology can be modified, via alloy...

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Bibliographic Details
Published in:Metallurgical and materials transactions. A, Physical metallurgy and materials science Physical metallurgy and materials science, 2019-03, Vol.50 (3), p.1333-1345
Main Authors: Hearn, William, Bogno, Abdoul-Aziz, Spinelli, Jose, Valloton, Jonas, Henein, Hani
Format: Article
Language:English
Subjects:
Aerospace industry
Alloys
Aluminum base alloys
Atomizing
Automobile industry
Automotive engineering
Characterization and Evaluation of Materials
Chemistry and Materials Science
Eutectics
Materials Science
Mechanical properties
Metallic Materials
Morphology
Nanotechnology
Rapid solidification
Silicon
Solidification
Structural Materials
Surfaces and Interfaces
Thin Films
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Summary:Hypo-eutectic Al-Si alloys are widely used in both the automotive and aerospace industries; however, they still have limited usage as structural materials, due to the inherent morphology of the Si phase that forms within the eutectic structure. This non-ideal Si morphology can be modified, via alloy additions and/or rapid solidification (RS), but the underlying mechanism(s) behind this is poorly understood. This work focused on understanding the influence of RS on the eutectic structure, for hypo-eutectic Al-10 wt pct Si alloys produced by Impulse Atomization and Differential Scanning Calorimetry. This study found that the eutectic Si forms into four distinct morphologies: (1) flaky, (2) fibrous, (3) globular + fibrous and (4) globular, depending on the solidification conditions. As a result, two solidification maps of the Si morphology are proposed, one based on local eutectic solidification conditions and another based on a solidification continuous cooling diagram (SCCT). Both maps help identify the required conditions for certain Si morphologies to form. Hardness measurements were also carried out and it was found that the Si morphology would influence the alloy hardness, with the highest value being achieved when the eutectic Si was globular. This result indicates that the Si morphology is an important factor that can alter the mechanical properties of hypo-eutectic Al-Si alloys.
ISSN:1073-5623
1543-1940
DOI:10.1007/s11661-018-5093-2