Liquid-to-glass transition in bulk glass-forming Cu60Ti20Zr20 alloy by molecular dynamics simulations

Local structural evolution of Fe54C18Cr16Mo12 bulk metallic glass during tensile deformation and a temperature elevation process: a molecular dynamics study

Mechanical and thermal properties of Fe₅₄C₁₈Cr₁₆Mo₁₂ bulk metallic glasses (BMGs) were investigated by molecular dynamics simulation with the 2NN MEAM potential. Local strain distribution results show a shear band develops homogeneously with the tensile fracture angle.

Atomic mechanism of liquid-glass transition for Ca7Mg3 alloy

The atomic mechanism of liquid-glass transition for Ca(7)Mg(3) alloy during the rapid quenching processes is studied by the molecular dynamics simulations. The temperature dependences of structural, thermodynamic, and dynamic properties during the liquid-glass transition have been investigated. It is found that onset temperatures where these different properties begin to deviate from the equilibrium liquid are identical and near the melting temperature T(m). The liquid-glass transition temperatures in structure (T(g)(Str)) and dynamics (T(g)(Dyn)) are identical and higher than the calorimetric one (T(g)(Cal)), which are consistent with many experiments and computer simulations. The solid- and liquid-like atoms are defined by the Debye-Waller factor. It reveals that the solid-like atoms hold lower potential and higher degree of local order. On the basis of the evolution of solid-like atoms, the atomic mechanisms in structure, thermodynamics, and dynamics transition are systematically elucidated, which are consistent with the potential energy landscape.

Dynamics of a single atom in ternary metallic glass-forming Cu₆₀Ti(x)Zr(40-x) melts by molecular-dynamics simulations

The recently proposed universality near the glass transition [M. Tokuyama, Phys. Rev. E 80, 031503 (2009)] is tested for the dynamics of a single atom in ternary metallic glass-forming Cu₆₀Ti(x)Zr(40-x) melts by using molecular-dynamics simulations for different compositions, x = 10, 20, and 30. First, a master curve for the dynamics of the atom, such as the mean-square and mean-fourth displacements, is shown to exist independently of x if the long-time self-diffusion coefficient D(S)(L) has the same value. Second, a master curve for the temperature dependence of D(S)(L) is shown to exist independently of x. Finally, master curves for characteristic length and time scales of the atom are also shown to exist independently of x.

Single master curve for self-diffusion coefficients in distinctly different glass-forming liquids

An existence of a single master curve for the long-time self-diffusion coefficients D(S)(L)(T) in diversely different glass-forming liquids is predicted over wide temperature T ranges above the glass transition point T(g) by analyzing various experimental and simulation data consistently from a unified point of view based on the mean-field theory recently developed. In order to scale those data appropriately, the power-law dependence of the α- and the β-relaxation times on D(S)(L) is used. Then, it is shown that any equilibrium data for self-diffusion of atom in different systems are all collapsed onto a singular function f(T(f)((α))/T) , where T(f)((α)) is a fictive singular temperature of atom α. Thus, we emphasize that any equilibrium self-diffusion data can be described by a single master curve f(x) above T(g)(>T(f)), while the data out of equilibrium start to deviate from f(x) around T(g).

Universality in multicomponent glass-forming liquids near the glass transition

The slow dynamics of a single particle in multicomponent glass-forming systems including fragile and strong glasses is studied from a unified point of view. The simulation results on two different systems, bulk glass-forming Cu60Ti20Zr20 melt and network-forming SiO2 , melt are analyzed by the mean-field theory (MFT) recently proposed and are compared with other systems near the glass transition. It is shown that the simulation results for the mean-square displacement are all collapsed into a master curve given by MFT if a long-time self-diffusion coefficient has the same value in each system. It is also shown that each long-time self-diffusion coefficient is described well by a singular function predicted recently from first principles. Thus, we conclude that there exists a simple universal mechanism near the glass transition even among any diversely different glass-forming systems.