Microstructural percolation assisted breakthrough of trade-off between strength and ductility in CuZr-based metallic glass composites

Abstract

As two important mechanical properties, strength and ductility generally tend to be muturally exclusive in conventional engineering materials. The breakthrough of such a trade-off has been potentiated by the recently developed CuZr-based bulk metallic glass (BMG) composites ductilized by a shape memory CuZr(B2) phase. Here the microstructural dependences of tensile properties for the CuZr-based BMG composites were elucidated qualitatively and modeled quantitatively, and the underlying mechanisms were unraveled. Through the microstructural percolation induced by matching the length scales of particle size and interparticle spacing, a notable breakthrough was achieved in the composites that the general conflicts between strength and ductility can be defeated. This study is expected to greatly aid in the microstructural design and tailoring for improved properties of BMG composites. It also has implications for the development of strong and ductile materials in the future.

Tuning plasticity of in-situ dendrite metallic glass composites via the dendrite-volume-fraction-dependent shear banding

“…The A8 alloy (referred to as the composite containing 8% of dendrites, see Table 1) fractures catastrophically at the strength of 1780 ± 35 MPa without detectable plasticity, similar to its glass matrix [33]. decreases linearly with the increase in f d , which can be reasonably described by the rule of mixtures [13,32]: [33,36]. As opposed to the yield strengths, a nonlinear enhancement of the plasticity was observed [13,32], showing the percolation transition, i.e., the onset of macroscopic plasticity [37,38], around the critical volume fraction 21%.…”

“…decreases linearly with the increase in f d , which can be reasonably described by the rule of mixtures [13,32]: [33,36]. As opposed to the yield strengths, a nonlinear enhancement of the plasticity was observed [13,32], showing the percolation transition, i.e., the onset of macroscopic plasticity [37,38], around the critical volume fraction 21%. And the plastic strains versus the volume fraction exhibits an S-shape curve that can be separated into three regions:…”

“…(2) . Noting that reinforcement particles act both as nucleation sites as well as obstacles to shear band propagation, the spatial configuration of the crystalline phases at the percolation threshold will be dependent on details of the glass composition and structure, as well as, e.g., the shape and average length scale of the reinforcement phases [13,27,32].…”

“…Among these, the volume fraction is a structural parameter to effectively tune the composite's properties. It was found that, the plastic deformation exhibits a nonlinear enhancement as the volume fraction of crystalline phases increases above a critical value [13,27,32]. Lee et al [13] and Liu et al [32] have ascribed this phenomenon to percolation of shear banding, corresponding to a specific configuration of crystalline phases' distribution.…”

“…It was found that, the plastic deformation exhibits a nonlinear enhancement as the volume fraction of crystalline phases increases above a critical value [13,27,32]. Lee et al [13] and Liu et al [32] have ascribed this phenomenon to percolation of shear banding, corresponding to a specific configuration of crystalline phases' distribution. However, the picture of how shear banding evolves in composites with increasing volume fraction of crystalline phase remains unclear up to now, and the relationship between the percolation point of global plasticity and the spatial configuration of crystalline phases also deserves further investigation.…”