Low-temperature plasticity anomaly in the bulk metallic glass Zr64.13Cu15.75Ni10.12Al10

Abstract

The plastic deformation and compression fracture of cylindrical samples of the bulk metallic glass Zr64.13Cu15.75Ni10.12Al10 have been studied in the temperature range 300–4.2K. The deformation curve at 300K is serrated due to the propagation of narrow shear bands. Catastrophic, uncontrollable fracture of samples, occurring as a result of the propagation of a macroscopic shear band with speed (of the order of 103m∕s) comparable to the sound speed, is observed at deformation ∼3–4%. When the temperature is lowered from 300 to 170 and 77K the deformation changes from serrated to smooth. An interesting low-temperature anomaly of the deformation process is found: “slow” (with speed of the order of 10−6m∕s) propagation of a single macroscopic shear band is observed at 170 and 77K. When the samples are cooled to 4.2K their macroscopic plasticity vanishes, and they undergo fracture, just as at 300K, as a result of the propagation of a catastrophic shear band with near-sound speed.

Shear transformation zone volume determining ductile–brittle transition of bulk metallic glasses

“…(6). Tabachnikova et al [12] have shown that with the temperature decrease to 77 K from room temperature, both the compressive strength and plasticity of Zr 64. 13 225 at 77 K might also be ascribed to the decrease of the STZ volume due to low temperature, where nano-scaled "chevron" patterns rather than vein patterns on the low temperature fracture surface indicate an apparent decrease in the plasticity [7].…”

“…It is therefore expected that these materials should not undergo DBT process. However, the DBT phenomena, as first reported by Wu and Spaepen [6], have been widely observed in metallic glasses [7][8][9][10][11][12][13][14][15][16]. Due to the practical and scientific significance of this behavior, it has attracted much attention.…”

Ambient temperature embrittlement of a Zr-based bulk metallic glass

“…Such plasticity improvement was attributed to multiple-nucleation of shear bands at low temperature [1,5,7]. Nevertheless, there are also some sporadic papers showing different trends [13][14][15]. Thus, one question naturally arises.…”

Mechanical Properties and Deformation Behavior of Bulk Metallic Glasses

“…Low-temperature measurements have also been performed [109][110][111] and demonstrated the increase in the maximum compressive stress with decreasing testing temperature. The stress-strain diagrams for the typical glassy Zr 64.13 Ni 10.12 Cu 15.75 Al 10 alloy tested at room temperature and close to boiling liquid nitrogen (LN 2 ) temperature are shown in Figure 5.…”