Solid State Phenomena Vol. 310

Abstract: A series of computer experiments using the molecular dynamics method, imitating the processes of the argon particles system cooling at different cooling rates, was carried out. As a result of modeling, solid phases of varying degrees of order were obtained, a comparative analysis of structures was performed using the calculation of the radial distribution functions of particles and using the author’s algorithm for recognizing clusters of a crystal structure.

Abstract: The elastic properties of the Zr₅₀Cu₄₀Ag₁₀ metallic alloy, such as the bulk modulus B, the shear modulus G, the Young’s modulus E and the Poisson’s ratio σ, are investigated by molecular dynamics simulation in the temperature range T=250–2000 K and at an external pressure of p=1.0 bar. It is shown that the liquid–glass transition is accompanied by a considerable increase in the shear modulus G and the Young’s modulus E (by more than 50%). The temperature dependence of the Poisson’s ratio exhibits a sharp fall from typical values for metals of approximately 0.32–0.33 to low values (close to zero), which are characteristic for brittle bulk metallic glasses. Non-monotonic temperature dependence of the longitudinal and transverse sound velocity near the liquid-glass transition is also observed. The glass forming ability of the alloy is evaluated in terms of the fragility index m. Its value is m≈64 for the Zr₅₀Cu₄₀Ag₁₀ metallic glass, which is in a good agreement with the experimental data for the Zr-based metallic glasses.

Abstract: Titanium nickelide (nitinol) is of great applied interest in various industries due to unique combination of its physical and mechanical characteristics. In the present work, we consider the possibility of obtaining nitinol with mesoporous structure by rapidly cooling the molten sample to room temperature. Based on molecular dynamics simulation data, it was shown that the rapid cooling of the nitinol melt leads to formation of a porous structure. It was shown that the inner pore wall is formed mainly by titanium atoms, which provide biocompatibility of nitinol. It was found that the porosity of nitinol weakly depends on the cooling rate, while the porosity increases linearly with decreasing melt density.