Exfoliation of Magnesium-Graphite Composites: A Combined Metallographic and Analytical Approach
ARMY MATERIALS AND MECHANICS RESEARCH CENTER WATERTOWN MA
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An investigation was conducted to determine and eliminate the cause of localized exfoliation in magnesium and a magnesium alloy AZ91C reinforced with graphite fibers. These composites were prepared by liquid phase hot pressing using a titanium intermediate to promote wetting, infiltration, and bonding between the MgMg alloy and the graphite fibers. A multidisciplinary approach involving metallography, scanning electron microscopy, microprobe analysis, electron spectroscopy, infrared spectroscopy and gas chromatography was used to study exfoliated and unexfoliated regions of these composites. The results of these studies indicate that exfoliation in both Mg and the Mg alloy matrix composites occurs when there is poor wetting and bonding and that it can be completely prevented by achieving good wetting bonding. It was also found that eliminating of aluminum as an alloying element improves the suitability of Mg as a matrix for graphite fibers.
- Laminates and Composite Materials