Suppression of shear banding in amorphous ZrCuAl nanopillars by irradiation

Abstract

Using molecular dynamics simulations, model Zr50Cu40Al10 metallic glass (MG) nanopillars were subjected to simulated irradiation processes followed by uniaxial compression tests. As the intensity or dosage of irradiation increases, the plastic deformation mode of the MG nanopillars transits from localized shear banding to homogeneous shear flow. The suppression of shear banding in MG nanopillars is due to irradiation-induced structural disordering. Furthermore, a correlation is found between the average potential energy of MG nanopillars and their deformation modes, common to both irradiation processing and thermal processing. Our results imply that the homogeneous shear flow observed in experimental MG nanopillars carved by focused ion beam may be due to irradiation damage instead of size effect.

Radiation response of amorphous metal alloys: Subcascades, thermal spikes and super-quenched zones

“…demonstrate that at high doses of low energy recoils (47.3 eV and 106.4 eV) deformation becomes increasingly homogeneous, as would be expected in rapidly quenched glasses [8]. However, Avchaciov et al simulated deformation of 20 keV irradiated amorphous Cu 64 Zr 36 and found an increase in strain localization in the irradiated alloy [18].…”

“…Previous modeling studies have investigated radiation response in metallic glass compositions, including Ni-P [16], Cu-Ti [7,17], Cu-Zr [8,18] and Cu-Nb [19]. We choose to study amorphous alloys of copper (Cu) and niobium (Nb) (a-Cu x Nb 1Àx ) because their atomic-scale structure has been characterized experimentally [20] and a reliable embedded atom method (EAM) interatomic potential has been constructed to model them [21].…”

“…Changes in structure [7] and mechanical properties [7,8] of irradiated glasses may be mapped to unirradiated configurations synthesized with different quench rates. In analogy to relaxation of rapidly quenched glasses upon annealing [9], radiation-induced changes in the mechanical properties of some metallic glasses may also be reversed by annealing [10][11][12][13].…”

Room Temperature Homogeneous Ductility of Micrometer‐Sized Metallic Glass

“…Given that the above contradicting reports in search of the size-dependent cross-over in fl ow behavior all employ FIB for sample preparation, it seems clear that the preparation method may be one of the factors responsible for the apparent "brittle-to-ductile" transition. Further support for this irradiation induced "brittle-to-ductile" transition in small scale systems is given by molecular dynamics (MD) simulations, [ 30 ] where the suppression of shear-banding is explained by irradiation induced atomic scale (re)disordering that is characterized by the average potential energy of the system.…”

Prediction of Spontaneous Plastic Deformation of Irradiated Metallic Glasses due to Thermal Spike-Induced Plasticity

“…[12,19,25,26] However, TSs have a distinctly different effect on atomic structure evolution in amorphous metals. [27][28][29] By computing voxel-level strains, we find that the material immediately adjacent to TSs undergoes permanent plastic deformation. The tensile work-equivalent plastic strain p of black voxels in Figure 1(c) exceeds 1.25%.…”