Fabrication, microstructure characterization and mechanical property of the Ti6Al4V-(NiTif/Mg3AlZn) laminate composite

Abstract

In this paper, an innovative NiTi shape memory alloy fiber reinforced Ti6Al4V-(NiTif/Mg3AlZn) metal-metal laminate composite (SMAFR-MML) was successfully fabricated by vacuum hot pressing method using Ti6Al4V (TC4) foils, Mg3AlZn (AZ31) foils, commercial pure Al foils and continuous NiTi shape memory alloy fibers. The phase constituent analyses of the composites were conducted by X-ray diffractometer (XRD). The microstructure characterizations and elemental analyses of the composites were examined by a field emission scanning electron microscopy (FE-SEM) equipped with an energy dispersive spectroscopy (EDS). The tensile mechanical properties of the composites were comparatively investigated with those of the MML composite without NiTi fibers and as-received AZ31 foils. Results showed that a continuous Mg-Ti elements diffusion layer with a thickness of ∼2.0 μm was formed at the TC4/AZ31 interface, and Mg2Al3 as well as Al8Mn5 phases discontinuously precipitated in the AZ31 matrix near the interface. Similarly, a continuous ∼1.7 μm thick Mg-Ni-Ti elements diffusion layer was formed at the AZ31/NiTi fiber interface, and Al3Ni2 phases precipitated adjacent to the NiTi fiber at the interface. Compared with the AZ31 foils and the MML composite without NiTi fibers, the SMAFR-MML composite possessed a superior comprehensive mechanical properties, which are attributed to the high strength and toughness of TC4 layers, good interfacial bonding at AZ31/NiTif interface and the plastic deformation and fracture of NiTi fibers during tensile process.