Microstructure and mechanical properties of TiNiSMA wire reinforced Mg alloy matrix composite

Magnesium alloy matrix composite reinforced by continuous TiNi shape memory alloy (SMA) wire was fabricated by Pulsed Current Hot Pressing (PCHP) of TiNi SMA wires sandwiched with a pair of AZ31 Mg alloy plates, and its microstructure and mechanical properties were examined. The Mg alloy plates with 20 vol.% of the TiNi wires were readily hot pressed into a composite at the temperature of 773 K for a total processing time of 0.6 ks. During the processing, the thickness of the preform composed of Mg plates and TiNi wires decreased drastically at the temperature between 400 K and 650 K, resulting in the bonding between the wire and the matrix plates. As a reaction occurred insubstantially in the vicinity of the boundary between Mg alloy plates and TiNi wire, no homogeneous interfacial reaction layer was formed. The tensile yield stresses of the composite deformed in tension at 373 and 423 K were higher by about 68 MPa and 87 MPa than that at 293 K, respectively. At the test temperature range, both the yield stress and elongation of the composite increased with increasing temperature. At temperatures higher than 373 K, the specific strength of the composite was higher than that of AZ31 Mg alloy.