Abstract
The effects of surface notches and loading mode on the mechanical deformation and mechanics of ZrNi metallic glass (MG) are studied using molecular dynamics simulations based on the many-body embedded-atom potential. The effects are investigated in terms of atomic trajectories, shear strain distributions, and stress-strain curves. The simulation results show that for ZrNi MG, resistance to shear deformation (shear strain > 200%) before breaking is much greater than that to tensile and compressive deformation. For ZrNi MG under tension, a pre-existing notch leads to earlier necking and breaking. Significant stress concentration occurs around the notch root when the notch length (L) is 3 nm or above, and dominates plastic deformation. For ZrNi MG under compression, a pre-existing notch is completely filled by neighboring atoms at the initial stage of compression. A pre-existing notch leads to single-edge barreling and weakens a sample’s ultimate strength when the L value is 3 nm or above. For ZrNi MG under shear loading, a pre-existing notch does not influence the shear modulus of samples; however, their ultimate strength decreases with increasing L value.
Highlights
The present work investigates the effects of surface notches and loading mode on the mechanical deformation and mechanics of ZrNi metallic glass (MG) utilizing Molecular dynamics (MD) simulation
Regions with relatively large shear strain indicate a high density of shear transformation,[22] which represents the collective and inelastic shearing of atoms in response to an applied shear stress;[23,24] these regions are Shear transformation zones (STZs) and are distributed independently[22] for MGs
MD simulations were used to investigate the effects of surface notches and loading mode on the deformation and mechanics of ZrNi MG
Summary
Metallic glasses (MGs) have attracted a lot of attention due to their excellent thermoformability and mechanical properties, such as high strength and hardness,[1,2,3] good bending ductility,[4,5] good fatigue and wear resistance,[6] and high elastic limit,[1,7] for application in nanomolds, microelectromechanical systems, electronic devices, and functional films.[8,9,10,11,12,13] Unlike traditional crystalline metals, MGs have a disordered atomic structure and have deformation mechanisms completely different from those of crystalline metals (dislocation nucleation and propagation). Li et al.[17] analyzed the mechanical properties of Ni40Zr60 MG with and without surface notches under tensile loading. They found that the formation of free volume is related to strain hardening and the critical amount of free volume and that the strength and ductility greatly decrease with increasing notch size. Wu18 studied the nanotribological properties of Cu50Zr50 MGs and found that the friction coefficient decreases with increasing scratch depth, scratch speed, and Zr content in MGs. Feng et al.[19] found that a higher quenching temperature or cooling rate decreased the short-range order and cluster size in MGs. Feng et al.[19] found that a higher quenching temperature or cooling rate decreased the short-range order and cluster size in MGs Under such conditions, shear transformations interact more strongly with each other, and propagate throughout the MGs. The present work investigates the effects of surface notches and loading mode on the mechanical deformation and mechanics of ZrNi MG utilizing MD simulation. The results are discussed in terms of atomic trajectories, shear strain distributions, and stress-strain curves
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