Compressive failure of Al alloy matrix syntactic foams manufactured by melt infiltration

Al alloy syntactic foams containing hollow or porous ceramic microspheres were fabricated by melt infiltration. Tensile, shear, confined compressive and unconfined compressive tests were performed and the failure modes in compression were studied. The tensile and shear strengths were insensitive to the types of the ceramic microspheres. In confined compression, all syntactic foams failed by progressive collapse of the microspheres. Different failure mechanisms were observed in unconfined compression. The syntactic foams with stronger ceramic microspheres failed by Griffith rupture, with cracks oriented at approximately 30° to the loading direction and the compressive strengths being about eight times of their tensile strengths. The syntactic foams with weaker ceramic microspheres failed by progressive collapse of the ceramic microspheres and had lower compressive strengths.