High-Pressure Equation of the State of a Zirconium-Based Bulk Metallic Glass

The high stress U _s -U _p Hugoniot equation of state (EOS) of a zirconium-based bulk metallic glass (BMG, Zr₅₇Nb₅Cu_15.4Ni_12.6Al₁₀) was determined using plate impact experiments on disk-shaped samples of 10-mm diameter and 2-mm thickness. The National Institute for Materials Science (NIMS) two-stage light-gas gun was used for the high stress measurements (∼26 to 123 GPa), and the Georgia Institute of Technology (GT) single-stage gas gun was used for the lower stress measurements (∼5 to 26 GPa). The NIMS experiments were instrumented with streak photography and used the inclined mirror (IM) method to simultaneously measure shock velocity and free surface velocity. The GT experiments used polyvinylidene fluoride (PVDF) stress gages and velocity interferometry (VISAR) to simultaneously measure the shock velocity, free surface velocity, and stress. Results from the streak camera records and PVDF gages + VISAR traces, as well as impedance matching calculations, were used to generate the U _s -U _p Hugoniot EOS for the BMG over a wide range of stresses. The U _s -U _p data show evidence of a low pressure phase, a transition to a mixed phase region at ∼26 GPa, followed by transition at ∼67 GPa to a high-pressure phase of bulk modulus of 288 GPa.