Mechanical Behaviors Of Bulk Metallic Glass And Bulk-metallic-glass-matrix Composites Under High Rate Dynamic Loading

Bulk metallic glasses (BMGs) are a new kind of advanced structural materials, which exhibit high strengh, large elastic limit, super corrosion resistance, high fatigue endurance, etc. A series of advantages in performances render them potential as worldwide leading-edge materials. However, a catastrophic failure usually happens once BMGs yield upon loading at room temperature, accompanied by the fast propation of localized shear bands.This brittle fracture behavior without appropriate fracture resistance hinders their future applictions as structural materials.To allevicte this problem, in-situ dendrite reinforced metallic glass matrix composites have been developed recently, which combine high strength and improved toughness.While for actual structural engineering applications of these amouphous alloys and in-situ composites, many kinds of extreme conditions other than quasi-static loadings at ambient temperature should be appreciated. For instance, they may be subjected to high speed dynamic loading. Considering the influence of geometrical shape and composition on the mechanical properties of materials, in this study, the mechanical behaviors of hollow Zr-based BMGs and a kind of in-situ dendrite reinforced Ti-based metallic glass matrix composite upon high rate dynamic loading have been investigated. It can be seen that the hollow Zr-based BMGs exhibit little ductility, but the in-situ dendrite reinforced Ti-based metallic glass matrix composite exhibits distinguished work hardening., and it’s plastic stain appropriates to10.6%. In addition, it is known that processing is one of the most important procedures into final products. Up to date, almost all the processing for metallic glasses is at a temperature within the supercooled liquid region, since the bulk metallic glass matrix is completely viscous in this region, it can easily undergo a homogeneous deformation, instead of the availability of "defects" localized shear bands. However, the machining processing usually results in the presence of shear bands and voids on the surface rather than a smooth surface at room temperature. In this paper, dynamic punchforming under high rate is employed to process the in-situ dendrite reinforced Zr-based metallic glass matrix composite, and no macroscopic cracks or ruffles can be found.