Shear deformation capability of different metallic glasses

Abstract

The mechanical properties of Zr52.5Ni14.6Al10Cu17.9Ti5 and Ti40Zr25Ni3Cu12Be20 metallic glasses were investigated under uniaxial compressive loading and small punch loading, respectively. The Zr-based metallic glass displays higher density of shear bands, larger critical shear offsets and higher energy absorbing capability than the Ti-based metallic glass under the small punch tests. A concept of critical shear offset is proposed to explain the difference in shear deformation abilities or plasticity of different metallic glasses. The current experiments demonstrate that, in contrast with the small difference between the responses of the Zr- and Ti-based metallic glasses under uniaxial compressive loading, the biaxial tension produced by the small punch test is an effective way to evaluate the difference in shear deformation abilities and can be used to distinguish the brittleness or plasticity of various metallic glasses.

Transition of Failure Mode and Enhanced Plastic Deformation of Metallic Glass by Multiaxial Confinement

“…However, it is noted that the compressive plasticity of the Ti-based metallic glasses is near zero. [20] These results indicate that the brittle Ti-based metallic glass can also display a macroscopically high plasticity under the current SPT method with additional confinement, which must be highly related to the microscopically dense shear bands, and is discussed below.…”

“…[17] Recently, the mechanical properties of metallic glasses under biaxial tensile loading were studied by the small punch test (SPT). [18][19][20] It was interesting to find that the metallic glasses could be controlled to create regularly arrayed, fine, multiple shear bands under the SPT, indicating that metallic glasses essentially have a good plastic-deformation capability and thus high ductility under suitable loading conditions. The findings showed that the initiation and propagation of shear bands in metallic glasses strongly depend on the stress state.…”

“…However, under the SPT, some metallic glasses show a faint shear-deformation capability, such as Ti-based metallic glass, which exhibits a significantly unstable shear deformation and a different failure mode to that of Zr-based metallic glass. [20] Therefore, in this communication, the shear-deformation behavior of a Ti-based metallic glass under multiaxial confinement is evaluated and analyzed using the SPT. We confirm that under multiaxial confinement, the sheardeformation capability of a metallic glass can be greatly improved, and that the failure modes can also be changed under this confinement.…”

“…It is obvious that the load capability of sample S2 was increased with the confinement. According to the load-deflection curves, the mean plastic strain, e p (global plasticity), of samples S1 and S2 can be approximately calculated using Equation (1): [20] …”

“…Samples S1 and S2 both underwent a mixeddeformation process, forming radial and circumferential shear bands, respectively. [18][19][20] As summarized in Table 1, for sample S1, the radial-shear region was 2.69 mm in diameter, and the circumferential-shear region was 1.13 mm in diameter. The densities of the shear bands were 35.7 rad À1 in the circumferential direction and 2.1 Â 10 5 m À1 in the radial direction, respectively.…”