Critical Solid Solubility of the Ni-Ti System Determined by Molecular Dynamics Simulation and Ion Mixing

Abstract

From a realistic n-body potential of the Ni-Ti system, the critical concentrations of the Ni-and Tirich solid solutions were determined by molecular dynamics (MD) simulation to be 38 at% Ti and 15 at% Ni, respectively, beyond which a disordered atomic configuration was more stable than the respective crystalline solid solutions. It follows that the central composition range bounded by the critical solubilities, i.e. within 38-85 at% of Ti, can be considered as the glass-forming range of the system, which was confirmed by room temperature 200 keV xenon ion mixing of alternately deposited Ni-Ti multilayered films. Moreover, MD simulation of a Ni-Ti bilayer revealed that during the solid-state amorphization reaction, the growth of the amorphous interlayer followed exactly a t 1/2 law and grew faster towards the Ti lattice than to the Ni side. The physical origin of such an asymmetric behaviour was found to be due to a difference in critical solid solubilty of the constituent metals.

Thermal stability of nanometer range Ti/Ni multilayers

“…Recently, Ti/Ni thin film alloy fabricated via ML route has also generated significant interest among the researcher because of their unique shape memory and super elastic effects [8][9][10]. In addition to above applications, Ti/ Ni ML have been studied by various workers to understand the basic phenomenon of solid-state reaction leading to solid state amorphization (SSA) [11][12][13][14][15][16]. In this context, Ti/Ni ML system is considered as a model that fulfils all the requirements such as a large difference in Gibbs free energy of intermixing and abnormally fast diffusion of one of the constituent element favoring SSA.…”

Favored composition region for metallic glass formation and atomic configurations in the ternary Ni–Zr–Ti system derived from n-body potential through molecular dynamics simulations

“…Therefore, for the Ni-Zr system, an amorphous alloy would form when its composition falls into the composition range bounded by the two determined critical solid solubilities and the GFR of the system is about 23-87 at.% of Zr with an error of about 3 at.%. 51 By monitoring the projections of atomic positions and pair correlation function g(r)s of the a certain system, the GFR of the Ni-Ti system can also be identified as about 25-87 at.% of Ti. While for the Zr-Ti system, lattices of alloys remain hcp structures and g(r)s curves can keep the hcp peaks at all compositions, suggesting that the Zr-Ti alloys can remain in the initial hcp crystal structure in whole composition range.…”

Metastable isomorphous phase diagram of the peritectic Ni-Ru system predicted byab initioand molecular dynamics calculations

“…4,5 Since the 1980s, much effort has also been made to study one of the fundamental issues, i.e., to clarify the physical origin of the crystal-to-amorphous transition as well as to predict the glass-forming ability/range (GFA/GFR) as an intrinsic property of a system. [6][7][8][9][10] Based on extensive IBM studies, Liu et al have proposed a parameter, namely the maximum possible amorphization range (abbreviated MPAR), 5,11 to approximately yet quantitatively describe the GFA/GFR of a system, and it is defined as the total width of the two-phase region(s) and equals 100%, as the whole composition range, minus the two maximum terminal solid solubilities observed from the equilibrium phase diagram of the system. The definition means that the larger the MPAR, the greater the GFA/ GFR, i.e., the broader the composition range favoring amorphous alloy formation, and that when the MPAR is equal to 0, an amorphous alloy is hard to obtain.…”