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Thisstudy combines the molecular dynamics (MD) simulations andfirst-principles approach to explain the experimental observationthat the best glass formers of Cu–Zr bulk metallic glasses(BMGs) have the compositions Cu50Zr50and Cu64Zr36. These two best glass formers are first calculatedto be most abundantly composed of Cu6Zr7andCu8Zr5icosahedral clusters when compared inthe compositional range of CuxZr100–x(45 ≤ x≤ 70), andthen these two icosahedral clusters are calculated to have the lowestformation energy among the icosahedral clusters CuxZr13–x(3 ≤ x≤ 10), as well as possessing some characteristicsin electronic structure and chemical hardness. Through understandingthe properties of specific icosahedral clusters in metallic glasses,the structural and energetic contribution to the glass-forming abilityare systematically discussed. [ABSTRACT FROM AUTHOR]

This article tries to uncover the physical reason of Cu precipitation from an Fe matrix at the electronic level. The general rule is obtained that the more bonds among Cu atoms, the more stable the system is. It was shown that Cu would precipitate from the matrix with Fe spin-polarization but not without spin-polarization. The partial density of states (PDOS) analysis illustrated that the d states of Fe near the Fermi level potentially have strong interaction with other atoms, but Cu d states below the Fermi level lack this potential, which results in weak covalent d orbital interaction between Fe and Cu. Furthermore, the charge density difference also confirmed the weaker bond between Fe and Cu with spin-polarization compared to without spin-polarization, due to the decreased charge between them. In addition, the {110} interface energy between Fe and Cu, estimated by the “dangling bond”, is 676.3 mJ m−2, which agrees with the DFT calculation, 414.2 mJ m−2. Finally, this study also revealed that Ni atoms can reduce the “dangling bond” when it locates at the interface and separates Fe and Cu. [ABSTRACT FROM AUTHOR]

Abstract: First-principles calculations based on density functional theory are performed to study the adsorption and diffusion of hydrogen on ordered Ni3Fe(111) surface and in the bulk. The adsorption of H2 molecule on surface is weak, but the adsorption of H atom on surface is strong. H2 decomposition on surface can easily take place and the largest barrier of H2 decomposition is 0.25 eV. The adsorption of H on surface and in the bulk is both exothermic relative to isolated H atom. The minimum barrier for H diffusion between two nearest sites on surface is 0.11 eV, indicating the H has good mobility on the surface. The minimum barrier for H diffusion from surface to the first subsurface is 0.78 eV. Once H atom diffuses into the first subsurface, it can more easily further diffuse into bulk with barrier values in the range 0.22–0.46 eV, which are very close to those values obtained in ordered bulk Ni3Fe. Moreover, the dependence of adsorption and diffusion properties on surface coverage is also discussed. [Copyright &y& Elsevier]