Processing of TiNi SMA fiber reinforced AZ31 Mg alloy matrix composite by pulsed current hot pressing

Abstract

Magnesium alloy matrix composite reinforced by continuous TiNi shape memory alloy (SMA) fiber was fabricated by pulsed current hot pressing (PCHP) of TiNi SMA fibers 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 fibers 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 fibers decreased drastically at the temperature between 400 and 650 K, resulting in the bonding between the fiber and the matrix plates occurred. As a reaction occurred insubstantially in the vicinity of the boundary between Mg alloy plates and TiNi fiber, 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 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.