First-principles simulation of the elastic properties of multicomponent amorphous steels

Abstract

The local atomic structure and elastic properties of two series of multicomponent amorphous steels-with and without phosphorus addition-have been investigated by ab initio molecular dynamics. A comparison of neutron pair-distribution functions allowed the difference in local atomic organization for these two series to be explained in terms of the atomic size effect. The conclusions drawn on the basis of "empirical" consideration were confirmed by the results of first-principles simulations. The structural models obtained in the course of ab initio molecular-dynamics calculations were used for the simulation of the elastic properties and the results of the modeling revealed a close agreement with the experiment. This allowed us to elucidate a role of particular chemical elements in improving the ductility of particular compositions.

NMR Signature of Evolution of Ductile-to-Brittle Transition in Bulk Metallic Glasses

“…Classical structural models such as free volume [3] or shear transformation zone (STZ) [4], and dense random packing [5] or efficient cluster packing [6,7] theories have been used to describe plastic flow and fracture nicely, whereas those models in terms of packing based on atomic size and configuration (local topology and symmetry [8]) fails to take consideration of the details of the nature of atomic bonding in MGs, which is indispensable for a better understanding of their mechanical behavior. Recently, theoretical calculations illuminated that the hybrid character of interatomic bond of multicompositions contribute to the elastic properties [9], and bond flexibility or mobility might determine intrinsic plasticity versus brittleness properties [10,11]. Nevertheless, the order parameter(s) which can be accessed by experiments to characterize the nature of bond mobility and its evolution upon alloying in MGs is still lacking.…”

Mechanical properties of structural amorphous steels: Intrinsic correlations, conflicts, and optimizing strategies

“…Furthermore, according to the first-principles simulation, the bonds between P and metals are found to have a higher degree of metallic character compared with the cases of C and B. 95 Thus, increasing the P content helps soften the overall atomic bonds and improve the ductility/toughness. On the other hand, the bonds between C and metals are proved to be slightly shorter and thus should be stronger than those between B and metals.…”

“…On the other hand, the bonds between C and metals are proved to be slightly shorter and thus should be stronger than those between B and metals. 94,95 However, because C owns one more bonding electron than B, some electrons may be transferred from the solvent matrix to participate in the formation of the Metal-C bonds. 56,94 This results in the softening of the type II bonds and thus benefits the ductility/toughness.…”

First-principles study of the binary Ni60Ta40 metallic glass: The atomic structure and elastic properties

“…As an alternative approach to classical MD, recently ab initio molecular dynamics (AIMD) based on the first principles have been successfully employed to simulate the binary metallic alloys such as: Ni-P [15], Au-Ge [16], Mg-Cu [17], Zr-Pt [18], Cu-Zr [19][20][21][22], and Ni-Al [23]. The incorporation of ab initio total energy method into molecular dynamics not only ensures an accurate description for the interatomic interactions and local structures in the metallic glasses and but also helps design of BMG compositions with desirable physical properties [24]. As demonstrated in our recent paper [21], the "cluster-plus-glue-atom" model for Cu 64 Zr 36 BMG has been validated by AIMD simulation.…”