Work-hardenable Zr-based bulk metallic glass composites reinforced with ex-situ TiNi fibers

A series of work-hardenable bulk metallic glass composites (BMGCs) reinforced with ex-situ continuous TiNi fibers was fabricated with pressure infiltration casting. The BMGCs exhibited a combination of simultaneously enhanced fracture strength, improved plasticity and strong work-hardening ability under compression. More strikingly, the newly developed BMGCs show ductility up to 0.8 +/- 0.2% under tension. The ex-situ TiNi fibers not only effectively served as absorbers to prohibit the propagation of shear bands and promote the nucleation of multiple shear bands, but also incorporated the deformation-induced martensitic transformation, resulting in the observed strengthening/toughening. The fracture behavior analysis unveiled that the fracture upon compression is determined by the competition of the critical energy dissipation between shear banding and splitting, whilst the tensile fracture feature is associated with the stress field around the fibers. Additionally, it was revealed that the asymmetry between the tensile and compressive properties was due to the different axial and radial stresses applied on the TiNi fibers under these two loading conditions. Our study not only provides a methodology to develop novel high-performance BMGCs with a controllable microstructure in various alloy systems, but also sheds light on understanding deformation mechanisms and fracture behavior of BMGCs. (C) 2019 Elsevier B.V. All rights reserved.