Tensile properties of self-healing metal matrix composites reinforced with superelastic NiTi wires

Self-healing composites which have been designed by inspiring from the nature have attracted much attention in the recent years. In order to accomplish such a feature in manmade materials like polymers and metal matrix composites, many diverse methods have been announced such as hollow fiber and micro capsule embedment, liquidbased healing mechanism and so on. In the present work, self-healing effect due to the crack closure ability of the superelastic wires and partial melting of the matrix is experimentally investigated. The matrix of the composite specimens was made of Sn and Bi Superelastic NiTi wires were also embedded in the matrix to perform crack closure. Tensile specimens were fabricated according to ASTM-E08. The wire with the diameter of 0.014 in was embedded along the longitudinal axis of the specimens. In order to fabricate the specimens, Sn-13%Bi alloy was melted in a furnace at 300oC and casted into a preheated steel mold in which the wire have been embedded. First, the specimens were initially damaged using tensile machine. Then the damaged specimens were placed inside an oven at healing temperature and heated until the matrix got partially molten. Melted fraction of the matrix, in the presence of the superelastic effect of the wires provide required liquid phase to heal the crack