应变速率对Hf基大块金属玻璃的断裂机制和相分离的影响(英文)

Influences of Strain Rates on Fracture Mechanism and Phase Separation in Hf-Based Bulk Metallic Glass

采用INSTRON-5569试验机和分离式霍普金森压力杆对Hf445Cu27Ni13.5Ti5A110大块金属玻璃在不同应变速率下（10^-4 - 10^3S^-1）的压缩断裂行为进行了研究。准静态压缩条件下Hf44.5Cu27Ni13.5Ti5Al10大块金属玻璃不呈现应变速率敏感性，断裂强度值最高町达2400MPa，动态压缩条件下金属玻璃的屈服强度达到2840MPa。在断裂面上可观察到涟漪状和周期性条纹结构，涟漪状结构表明宏观为脆性断裂的金属玻璃在微观尺度上属于韧性断裂，周期性条纹结构与动态扩展裂纹前端和弹性波的相互作用有关。高的应变速率浮敛高的断裂强度和绝热温度，局部区域的绝热升温引起了压缩过程中Al的偏析和扩散，这对剪切带和裂纹的形成起到定的影响。

The uniaxial compressive fracture behavior of a Hf44.5Cu27Ni13.5Ti5Al10 bulk metallic glass （BMG） was investigated at different strain rates （10^-4 - 10^3 s^-1） by an INSTRON-5569 testing machine and Split Hopkinson Pressure Bar. The results show that the Hf44.5Cu27Ni13.5Ti5Al10 bulk metallic glass isn＇t sensitive to strain rate under the quasi-static compression condition. The fracture strength is 2400 MPa. The fracture strength is 2840 MPa under the dynamic compression. The dimple structure and periodical corrugation formed at the fracture surface were observed. The fracture mechanism attributed to ductile fracture in the range of micro-scale. In addition, interaction of elastic waves and the dynamic crack front plays an important role during the formation of periodic corrugations. The higher fracture stress and adiabatic temperature are caused by the higher dynamic compressive strain rate. Phase separation was formed by segregation and diffusion at the interface during compression and affected the formation of shear cracks/bands.