THE ROLE OF THE INTERFACE REGION ON THE MECHANICAL BEHAVIOR OF METAL-MATRIX COMPOSITES. DEFORMATION AND FRACTURE OF Al-CuAl2 EUTECTIC COMPOSITES.
DREXEL INST OF TECH PHILADELPHIA PA DEPT OF METALLURGICAL ENGINEERING
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The deformation and fracture behavior of directionally solidified Al-CuAl2 composites was studied in compression at room temperature in terms of the associated dislocation structures and fracture detail. In the as-grown condition, the lamellar structure shows fault lines consisting of discrete sub-grain boundaries and terminal lamellae. A uniform cellular structure develops across the Al-rich lamellae compression axis parallel to the plane of the lamellae with cell dimensions or approximately equal to 1 micron limited by the interlamellar spacing. Fracture initiates by cleavage of the CuAl2 lamellae. Voids resulting from separation of the CuAl2 coalesce leading to ductile failure across the adjacent Al-rich lamellae. The path of the self-propagating crack may be along the mid-plane of the CuAl2 lamellae, or at lamellar interfaces. Significant buckling or kinking of the CuAl2 lamellae takes place prior to fracture, the local fracture path following the contour of the lamellae. Observed yield and ultimate strength levels are significantly higher than values calculated from the rule of mixtures the strength of the composite approaches that of the CuAl2 phase alone. This is discussed in terms of the mode of loading and of the effect of small interlamellar spacings or approximately equal to 10 microns on strength. Author
- Laminates and Composite Materials
- Metallurgy and Metallography