Plastic behavior of Zr51Ti5Ni10Cu25Al9 metallic glass under planar shock loading

Abstract

Planar shock compression experiments are performed on a Zr-based bulk metallic glass (BMG), Zr51Ti5Ni10Cu25Al9 at peak shock stresses from 10 GPa to 27 GPa to investigate its plastic behavior under high pressure and high strain-rate. The particle velocity profiles measured at the free surface of the samples are analyzed to estimate longitudinal stresses of the Zr-based BMG in the shock loading process,and then shear stresses are obtained by comparing longitudinal stresses with a hydrostat. Though there is an obvious relaxation effect after elastic front, the Hugoniot elastic limit of the Zr-based BMG is found to increase with shock stress increasing. However, the shear stresses across the plastic shock front display stress hardening above the Hugoniot elastic limit followed by a stress relaxation (softening) to Hugoniot state, and the relaxation level also increases with shock stress increasing. The changes of shear stresses under planar shock compression are consistent with the results from molecular dynamic simulations, but obviously different from the pressure-shear impact experimental results or uniaxial stress impact experimental results.

Dynamic strength behavior of a Zr-based bulk metallic glass under shock loading

“…It is shown that the shear stress τ H is nearly constant around 1.6 GPa in the shock stress range of 10 GPa-21 GPa, and then it drastically decreases to 0.6 GPa at 38 GPa. The decrease of shear stress τ H with shock stress indicates the occurrence of a strain-softening effect, consistent with the experimental results, [8][9][10][11] and the MD simulation results from Arman et al [12] (also shown in Fig. 4(a)).…”

“…The data of shear stress τ H , including previously reported data from our work [11] on the same BMG, are shown in Fig. 4(a).…”

“…[8,9] With freesurface velocity profiles, we obtained the shear stress on the Hugoniot state up to 27 GPa for Zr 51 Ti 5 Ni 10 Cu 25 Al 9 by comparing shock stress to hydrostatic pressure, and the strainsoftening effect was also obvious. [11] The shear stress softening in BMG under shock compression was also found in the molecular dynamics (MD) simulation for a binary BMG (Cu 46 Zr 54 ) performed by Arman et al [12] As described above, the dynamic experiments on strength for BMGs are limited to low shock stress, and most are focused on the shock loading process. In fact, plate impact shock-release or shock-reload experiments are essential to comprehensively understand the dynamic strength behavior of various solid materials.…”

“…The samples used in this study are of the same composition (Zr 51 Ti 5 Ni 10 Cu 25 Al 9 ) as those used in our previous work [11,18] and were obtained from Liquid Metals Technology (Laboratory of the School of Materials Science and Engineering, Harbin Institute of Technology, China). The nominal density (ρ 0 ) for the samples used in this study is 6.740 g/cm 3 with a deviation of 0.004 g/cm 3 except for the sample used in shot No.…”

“…Recently, shock wave methods, which provide access to a much higher pressure and strain rate than can be obtained in the aforementioned experiments, have been used to study the dynamic strength behavior of BMGs. [7][8][9][10][11] Yuan et al [7] conducted pressure-shear impact experiments on Zr 41.25 Ti 13.75 Ni 10 Cu 12.5 Be 22.5 up to 8.8 GPa and found negligible effect of normal stress/hydrostatic pressure on the strength of this Zr-based BMG. Turneaure et al [8,9] performed plane shock wave experiments on another Zr-based BMG, Zr 56.7 Cu 15.3 Ni 12.5 Nb 5.0 Al 10.0 Y 0.5 , up to 16.4 GPa.…”