Atomistic Modeling of Crystal-to-Amorphous Transition and Associated Kinetics in the Ni−Nb System by Molecular Dynamics Simulations

Abstract

With the aid of ab initio calculations, an n-body potential of the Ni-Nb system is constructed under the Finnis-Sinclair formalism and the constructed potential is capable of not only reproducing some static physical properties but also revealing the atomistic mechanism of crystal-to-amorphous transition and associated kinetics. With application of the constructed potential, molecular dynamics simulations using the solid solution models reveal that the physical origin of crystal-to-amorphous transition is the crystalline lattice collapsing while the solute atoms are exceeding the critical solid solubilities, which are determined to be 19 atom % Ni and 13 atom % Nb for the Nb- and Ni-based solid solutions, respectively. It follows that an intrinsic glass-forming ability of the Ni-Nb system is within 19-87 atom % Ni, which matches well with that observed in ion beam mixing/solid-state reaction experiments. Simulations using the Nb/Ni/Nb (Ni/Nb/Ni) sandwich models indicate that the amorphous layer at the interfaces grows in a layer-by-layer mode and that, upon dissolving solute atoms, the Ni lattice approaches and exceeds its critical solid solubility faster than the Nb lattice, revealing an asymmetric behavior in growth kinetics. Moreover, an energy diagram is obtained by computing the energetic sequence of the Ni(x)Nb(100)(-)(x) alloy in fcc, bcc, and amorphous structures, respectively, over the entire composition range, and the diagram could serve as a guide for predicting the metastable alloy formation in the Ni-Nb system.

Interatomic potential to predict the glass-forming ability of Ni–Nb–Mo ternary alloys

“…It is found that binary NiNb bulk metallic glasses can be obtained by rapid solidification while Ni-Mo amorphous alloys can be synthesized by ion beam mixing (IBM) and solid state reaction [12][13][14]. In addition to the experimental exploration, theoretical studies such as molecular dynamics (MD) simulations were carried out to study the metallic glasses in Ni-Nb and NiMo systems [15][16][17]. The research results in both experiment and theory inspired our interest to investigate the metallic glass formation in the Ni-Nb-Mo system.…”

Formation of the Ni–Zr–Al Ternary Metallic Glasses Investigated by Interatomic Potential through Molecular Dynamic Simulation

“…By employing such method, the GFRs have been determined for some miscible (Ni-Mo, Ni-Ti, Ni-Zr, Ni-Hf, and NiNb), immiscible (Cu-W and Ag-Co) binary metal systems and Ni-Hf-Ti ternary system, and the calculated GFRs are in good agreement with the experimental observations. [7][8][9][10][11][12][13] It should be noted that the abovementioned method to evaluate the GFR is applied mainly to binary metal systems. For ternary metal systems, few corresponding study has so far been reported to predict the glass-forming composition range(s).…”

Solid-State Amorphization Observed in the Equilibrium-Immiscible Cu−Re System by Molecular Dynamics Simulations

“…One can, therefore, consider that the Re lattice is more difficult to turn into a disordered state. In fact, the asymmetric-growth has frequently been observed in solid-state amorphization of transition metal−metal systems, such as in the Ni−Mo, Ni−Nb, and Ni−Zr systems. − …”

“…In fact, the asymmetric-growth has frequently been observed in solid-state amorphization of transi-tion metal-metal systems, such as in the Ni-Mo, Ni-Nb, and Ni-Zr systems. [28][29][30] We now turn to discuss the detailed growth kinetics of the solid-state amorphization in the Cu-Re sandwich model. MD simulation shows that, with increasing the simulation time, the growing speed of the amorphous interlayer gradually slows down and eventually approaches zero.…”