In-situ tensile testing of ZrCu-based metallic glass composites

H C Sun,Y J Huang,X Xue,J F Sun,Z L Ning,S Pauly,G Wang,S Guo,W Z Liang

doi:10.1038/s41598-018-22925-2

Abstract

ZrCu-based bulk metallic glass composites (BMGCs) are well known for their plastic deformability, superior to traditional metallic glasses (MGs), which is attributed to a unique dual-phases structure, namely, the glassy matrix and unstable B2 phase. In the present study, in-situ tensile testing is used to trace the deformation process of a ZrCu-based BMGC. Three deformation stages of the BMGC, i.e., the elastic-elastic stage, the elastic-plastic stage, and the plastic-plastic stage are identified. In the elastic-elastic and elastic-plastic stages, the yield strength and elastic limit are major influenced by the volume fraction of the B2 crystals. In the plastic-plastic stage, the B2 phase stimulates the formation of multiple shear bands and deflects the direction of shear bands by disturbing the stress field in front of the crack tip. The deformation-induced martensitic transformation of the metastable B2 phase contributes to the plasticity and work hardening of the composite. This study highlights the formation and propagation of multiple shear bands and reveals the interactions of shear bands with structural heterogeneities in situ. Especially, the blocking of shear bands by crystals and the martensitic transformation of the B2 phase are critical for the mechanistic deformation process and illustrate the function of the B2 phase in the present BMGCs.

Highlights

Bulk metallic glasses (BMGs) have attracted widespread attention owing to their unique mechanical, chemical and physical properties, which makes them one of the most promising structural materials[1,2,3,4,5]
The metastable B2 phase can effectively promote the formation of multiple shear bands, and improve the plastic deformation capability of bulk metallic glassy composites (BMGCs), which is attributed to the complicated stress states of glassy matrix and the secondary phase[17,25,29,30]
Circular B2 phases with various diameters between 10 and 100 μm are distributed in the glassy matrix, which is similar to the microstructure of other CuZr-based BMGCs15,16,25,26

Summary

Introduction

Bulk metallic glasses (BMGs) have attracted widespread attention owing to their unique mechanical, chemical and physical properties, which makes them one of the most promising structural materials[1,2,3,4,5]. In-situ or ex-situ formed reinforcement phases were introduced to fabricate composite microstructures, which combine high strength and ductility. Such BMG composites enhance the limited plasticity of BMGs, especially the tensile plasticity[5]. The strain controlled martensitic transformation[19], transformation-induced plasticity (TRIP)[28] and work-hardening behavior of B2 phase reinforced BMGCs have not been well documented. Motivated by this deficiency, we investigate the deformation process of an B2 phase reinforced BMGCs in situ. The failure mechanisms of crystalline phases and glassy matrix are discussed

Methods

Results

Discussion

Conclusion