Gravity and Semisolid Casting of Self-Healing Aluminum Matrix Composites

This paper focuses on casting self-healing metal matrix composites with aluminum alloy as a matrix, and Nitinol fiber as reinforcement. The shape memory effect of Nitinol fibers can cause them to shrink and narrow or close the crack in cast matrix material and the bend test restores the shape. Self-healing metal matrix composite samples were cast using (a) semi solid squeeze casting after Rapid Slurry Formation and (b) gravity die casting. Casting procedures, microstructures, and mechanical properties are reported. The cast aluminum-Nitinol fiber composite samples prepared by both techniques were cracked under tensile and bending, both types of samples exhibit a reduction in the width of the crack in the samples upon heating the sample above the transformation temperature of Nitinol. Under certain conditions, the cracks in permanent mold cast alloys reinforced with Nitinol have been completely sealed leading to self-healing.