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Abstract: An interatomic potential was constructed and applied to conduct molecular dynamics simulations to study the glass forming compositions of the Hf–Cu–Ni system. Using solid solution model to compare relative stability of solid solution versus its disordered counterpart, simulations not only revealed that metallic glass formation was a result of collapsing of crystalline structures, but also determined a quadrilateral region in the Hf–Cu–Ni composition triangle, within which the formation of metallic glasses was favored. Moreover, energy difference between initial and resultant states was defined as driving force and molecular static calculations located its maximum value to be at Hf45Cu10Ni45, i.e. the optimized composition for metallic glass formation. [Copyright &y& Elsevier]

Abstract: Based on Miedema''s model, a Gibbs free energy diagram was first constructed for the Ag–Zr system and showed that the free energy of the Ag–Zr multilayered films could be higher than that of the corresponding supersaturated solid solutions and amorphous phase. Ion beam mixing with Ag90Zr10, Ag48Zr52 and Ag12Zr88 multilayered films was then conducted by 200keV xenon ions. It was found that an fcc supersaturated solid solution, a mixture of fcc and hcp metastable crystalline structures and an hcp supersaturated solid solution were formed and that amorphous phases were also observed to coexist with the metastable crystalline structures. The experimental observations concerning the non-equilibrium alloy formation matched well with the calculated Gibbs free energy diagram. [Copyright &y& Elsevier]

Abstract: Solid-state reactive diffusion between Ti and Al was investigated in the temperature range of 520–650°C by employing multi-laminated Ti/Al diffusion couples. In samples annealed up to 150h intermetallic TiAl3 is the only phase observed in the diffusion zone and the preferential formation of this compound in Ti/Al diffusion couples was predicted using an effective heat of formation model. The present work indicated that both Ti and Al diffused into each other and the growth of the TiAl3 layers occurred mainly towards the Al side. The TiAl3 growth changes from parabolic to linear kinetics between 575 and 600°C, characterized by activation energy of 33.2 and 295.8kJmol−1, respectively. It is suggested that the low-temperature kinetics is dominated by the diffusion of Ti atoms along the grain boundaries of the TiAl3 layers, while the reaction at the TiAl3/Al interfaces in the high-temperature regime is limited by the diffusion of Ti atoms in the Al foils as a result of increased solubility of Ti in Al with increasing temperature. [Copyright &y& Elsevier]

Abstract: Based on a newly constructed Cu–Al potential, Monte Carlo simulations predict not only a favored composition range of 17–73 at.% Al for amorphous alloy formation, but also an optimized composition of Cu50Al50, around which amorphous alloy formation would have a maximum driving force, defined by the energy difference of the initial solid solution and resultant disordered state. It suggests that the Cu50Al50 amorphous alloy could be more stable or attainable than other alloys in this system. Moreover, Voronoi tessellation analyses were conducted to characterize the atomic configurations of the Cu–Al amorphous alloys, and reveal a typical amorphous structure for the Cu50Al50 amorphous alloy, i.e. the dominating coordination numbers are around 14–15 in its atomic configuration. [Copyright &y& Elsevier]

Abstract: In the present review article, firstly, the experimental observations of the binary metallic glass formation by various glass-producing techniques are briefly summarized. Secondly, a detailed discussion is presented concerning the concepts of the glass-forming ability and glass-forming range (GFA/GFR) of a binary metal system. Meanwhile, some of the proposed empirical criteria or rules for predicting the binary metallic glass formation are discussed and compared with the experimental observations. Thirdly, it is proposed to take the interatomic potential of a binary metal system as the starting base to develop an atomistic theory capable of predicting the binary metallic glass formation. Accordingly, eight binary metal systems are selected as representatives to cover the various structural combinations as well as various thermodynamic characteristics. The n-body potentials of eight representative systems are then constructed with the aid of ab initio calculations. Applying the constructed and proven realistic n-body potentials, a series of molecular dynamics simulations are carried out. In the simulations, solid solution models are employed to compare the relative stability of the solid solution versus its competing disordered counterpart (i.e. the amorphous or metallic glass phase) as a function of the solute concentration. Finally, based on the realistic interatomic potentials, molecular dynamics simulations not only reveal the physical origin of the binary metallic glass formation, but also quantitatively determine, for each system, an alloy composition range, within which the disordered state is energetically favored, thus leading to establish the atomistic theory capable of predicting the GFR, i.e. the quantitative GFA, of the binary metal systems. [ABSTRACT FROM AUTHOR]