Interfacial carbides enhance dispersion and grain refinement in melt-processed SiC nanowhisker reinforced magnesium AZ91 alloy
File(s)
Published version (pre-proof)
Author(s)
Type
Journal Article
Abstract
β-SiC nanowhiskers (SiCwh) are promising reinforcements for magnesium matrix nanocomposites (MgMNCs) due to
their high strength and compatibility with Mg-Al alloys. In this study, SiCwh were successfully incorporated into AZ91
alloy via melt stirring. Synchrotron-based phase contrast tomography (PCT) was employed to characterise their three-dimensional dispersion. Notably, the formation of T2-Al₂MgC₂ ternary carbides was observed at the SiCwh–matrix
interface, indicating interfacial reactions during processing. Atomic-resolution transmission electron microscopy (TEM)
revealed nanoscale segregation within these carbides, suggesting a complex growth mechanism. The integration of
TEM, scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD) further identified
crystallographic orientation relationships (ORs) between SiCwh, T2-Al₂MgC₂, and α-Mg. These ORs suggest that T2-
Al₂MgC₂ promotes heterogeneous nucleation and grain refinement in the matrix. Moreover, interfacial reactions were
found to enhance wetting and dispersion of SiCwh, improving their distribution throughout the matrix. These findings
provide new mechanistic insights into interfacial phase formation and its influence on microstructure evolution.
Controlled interfacial reactions can be leveraged to optimize dispersion and refine grain structure in MgMNCs. Given
the simplicity and scalability of melt stirring, this approach offers a promising route for industrial production of SiC-reinforced Mg composites with enhanced properties.
their high strength and compatibility with Mg-Al alloys. In this study, SiCwh were successfully incorporated into AZ91
alloy via melt stirring. Synchrotron-based phase contrast tomography (PCT) was employed to characterise their three-dimensional dispersion. Notably, the formation of T2-Al₂MgC₂ ternary carbides was observed at the SiCwh–matrix
interface, indicating interfacial reactions during processing. Atomic-resolution transmission electron microscopy (TEM)
revealed nanoscale segregation within these carbides, suggesting a complex growth mechanism. The integration of
TEM, scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD) further identified
crystallographic orientation relationships (ORs) between SiCwh, T2-Al₂MgC₂, and α-Mg. These ORs suggest that T2-
Al₂MgC₂ promotes heterogeneous nucleation and grain refinement in the matrix. Moreover, interfacial reactions were
found to enhance wetting and dispersion of SiCwh, improving their distribution throughout the matrix. These findings
provide new mechanistic insights into interfacial phase formation and its influence on microstructure evolution.
Controlled interfacial reactions can be leveraged to optimize dispersion and refine grain structure in MgMNCs. Given
the simplicity and scalability of melt stirring, this approach offers a promising route for industrial production of SiC-reinforced Mg composites with enhanced properties.
Date Issued
2025-06-14
Date Acceptance
2025-06-13
Citation
Materials Characterization, 2025
ISSN
1044-5803
Publisher
Elsevier
Journal / Book Title
Materials Characterization
Copyright Statement
© 2025 Published by Elsevier Inc.
License URL
Identifier
10.1016/j.matchar.2025.115300
Subjects
Materials Characterization Z. Xu
A. Bonnin
B. Watts
et al.
Interfacial carbides enhance dispersion and grain refinement in melt-processed SiC nanowhisker reinforced magnesium AZ91 alloy
Materials Characterization (2024)
Magnesium matrix nanocomposites
Mg-SiC interface
multiscale characterisations
crystallographic orientation relationships
Publication Status
Published online
Article Number
115300
Date Publish Online
2025-06-14