Mechanical property and serration behavior of Ti-based metallic glassy composites reinforced by an in-situ dendritic phase

摘要

In situ Ti-based metallic glassy composites (MGCs) were fabricated by the addition of minor amount of Nb element. Compared to their monolithic glassy counterparts, the composites exhibited high yielding strength and plasticity at 300 K, and were characterized by not only a work-hardening behavior but also serration flows on stress-strain curves. Detailed statistical analysis revealed a power-law distribution in compression causing the serration of the Ti-based MGCs. Moreover, the exponent of the power-law function (beta) and the cut-off elastic energy density (Delta delta) increased with the increase of the volume fraction of the dendrite, increasing the stability of the plastic flow. As a result, the composite accommodates large deformation by accommodating the applied energy and thus increases the plasticity. Multiply shear bands formed on the surface and numerous shear terraces on the fracture surface of the specimens, evidencing macroscopic plasticity. The composite displayed a combination of increased strength and plasticity at a cryogenic temperature due to the increased nucleation sites of shear-bands.