Effect of Strain Rate on Compressive Behavior of a Zr-Based Metallic Glass under a Wide Range of Strain Rates.

Wenqing Li,Zhengwang Zhu,Zhengkun Li,Haifeng Zhang,Tieqiang Geng,Hong Li,Shaofan Ge,Huameng Fu,Aimin Wang,Long Zhang,Hongwei Zhang

doi:10.3390/ma13122861

Abstract

The strain rate effect on the mechanical behavior of amorphous alloys has aroused general interest. Most studies in this area have focused on quasi-static and high strain-rate compressive deformations. However, experimental results have been few, or even non-existent, under a moderate strain-rate loading. This article extends the traditional split Hopkinson pressure bar (SHPB) technique to characterize compressive deformation of an amorphous alloy at medium strain rates. The compressive behavior of Zr65.25Cu21.75Al8Ni4Nb1 amorphous alloy shows a negative strain rate effect on the yield strength with a quasi-static, moderate to high strain-rate range, and the fracture angle increases from 44° at 10−5 s−1 to 60° at 4000 s−1 as strain rate increases. Herein, we introduce a modified cooperative shear model to describe the compressive behavior of the current amorphous alloy under a broad strain rate range. The model predicts that the normalized yield strength will linearly descend with logarithmic strain rate when the strain rate is less than a critical strain rate, however, which rapidly decreases linearly with the square of the strain rate at high strain rates. The predicted data of the model are highly consistent with the current experimental results. These findings provide support for future engineering applications of amorphous alloys.

Highlights

Amorphous alloys have long been studied in terms of their high strength, high hardness, and high fracture toughness [1,2,3]
When the strain rate is less than 400 s−1, the nominal yield strength slowly decreases with an increase in the strain rate
The fracture angle increases with an increasing strain rate from 44◦ at 10−5 s−1 to 60◦ at 4000 s−1

Summary

Introduction

Amorphous alloys have long been studied in terms of their high strength, high hardness, and high fracture toughness [1,2,3]. The deformation behavior under different strain rates has been widely regarded. Bruck et al [4] believed that the strain rate effect on the strength is slight, and Hufnagel et al [5]. Reputed the idea of a negative strain rate effect. For most other types of amorphous alloy, there is a negative strain rate effect [18,19,20]. Owing to the brittleness of amorphous alloys, the compression behavior under different strain rates has received the most focus.

Methods

Results

Conclusion