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Abstract: The glass formation range of the Ni–Ti–Ta system was predicted by thermodynamic calculation based on Miedema's model and Alonso's method. To verify the theoretical prediction, five sets of Ni–Ti–Ta multilayered films with various compositions which were located in the predicted glass formation range were designed and the ion beam mixing was carried out to synthesize the amorphous alloys in the Ni–Ti–Ta system. It turned out that in all the five films with overall compositions of Ni72Ti21Ta7, Ni60Ti28Ta12, Ni49Ti34Ta17, Ni42Ti36Ta22, and Ni29Ti46Ta25, amorphous phases were indeed obtained, showing a good agreement between the experimental results and the thermodynamic calculation. Besides, it is expected that the Ni42Ti36Ta22 was much more favorable for the amorphous phase formation. [Copyright &y& Elsevier]

Highlights: [•] Glass forming ability of Fe40Ta20(Zr x Ti1− x )40 alloy is predicted by thermodynamic calculation. [•] The ion beam mixing results agree well with the thermodynamic calculation. [•] Amorphous phase separation was observed in Fe40Ta20Zr40 and other quaternary films. [ABSTRACT FROM AUTHOR]

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]

Ab initio calculations ascertain that the difference of formation enthalpy between order and disordered Cu3Au phases is at least 0.044 eV per atom. The calculations also suggest that the tetrahedral clustering configuration and its spatial distribution have drastic effect on the formation enthalpy of the disordered structure and that segregation of the Au atoms significantly lowers the formation enthalpy of the disordered phases. [ABSTRACT FROM AUTHOR]

Multilayered films of Rh1−x Ta x (x =25, 40, 50, 60) were prepared and irradiated by 200keV Xe+. A Gibbs free energy diagram of the Rh–Ta system was derived that predicted the glass-forming range to be within 43–65at.% of Ta. This agreed well with the experimental results. An interest phase transformation mechanism of Rh+Ta→fccI+fccII→fcc was observed and discussed. [Copyright &y& Elsevier]

Based on Miedema’s method for binary alloys, a thermodynamic model is proposed for calculating the standard formation enthalpies of ternary alloy systems. In the proposed model, both the atomic size difference of the constituent metals and the interaction between the third metal and the other two are taken into account. Compared with the Miedema’s original model, the newly proposed model can considerably improve the precision of calculation. [Copyright &y& Elsevier]

Abstract: For the Fe–Hf system characterized by a negative heat of formation, the glass-forming range/ability (GFR/GFA) was studied by thermodynamic calculation based on Miedema''s model and Alonso''s method. It was found that amorphous phase could be formed in a composition range of 24–86atom% Hf and that alloy with composition of Fe58Hf42 has the best GFA in the system. Experimentally, ion beam mixing was carried out to synthesize amorphous alloys in the Fe–Hf system. It turned out that in the samples with overall compositions located in the calculated GFR, amorphous phases were indeed obtained, whereas no amorphous phase was obtained if the overall compositions were located outside of the predicted region favoring for amorphous alloy formation, showing a good agreement between the experimental results and the thermodynamic calculation. [Copyright &y& Elsevier]

Abstract: Glass forming ability (GFA) and non-isothermal crystallization kinetics of Zr62.5Al12.1Cu7.95Ni17.45 bulk metallic glass were investigated. Its critical dimension is up to 7.5mm and its critical cooling rate is less than 40Ks−1, indicating its better GFA. It manifests two crystallization procedures and the second crystallization peak is more sensitive to heating rate than the first crystallization peak. The glass transition and crystallization both have remarkable kinetics effects. The apparent activation energies derived from the Kissinger plots are 175.24±27.59KJmol−1 for glass transition E g, 212.84±15.84KJmol−1 for onset crystallization E x, 230.51±23.85KJmol−1 for the first crystallization peak E p1 and 124.85±15.15KJmol−1 for the second crystallization peak E p2. [Copyright &y& Elsevier]

The phase relationship of Ti-Hf-Mn system was studied by diffusion triple and equilibrated alloy methods. The isothermal sections at 1373, 1273 and 1173 K for this system were constructed by means of electron probe microanalysis (EPMA) and X-ray diffraction (XRD) for the first time. No ternary phase was found in the system at all these temperatures. Six, seven and seven three-phase equilibria regions have been determined at 1373, 1273 and 1174 K, respectively. In this ternary system, the intermetallic compounds TiMn 2 , HfMn 2 and HfMn exhibit wide solid solution range at those three temperatures. In particular, the solution range of Ti in HfMn phase decreases with the increase of temperature, from 30.5 at% at 1173 K to 26.5 at% at 1373 K. Based on all available experimental data, the Ti-Hf-Mn system was evaluated using the CALPHAD method. The calculation results are in excellent agreement with the experimental data. Image 1 • 1373, 1273 and 1173 K isothermal sections of Ti-Hf-Mn system were first established over the whole composition range. • The solid solubility of Ti in HfMn phase was up to 20.6 at. % at 1373 K. • The continuous solid solution of (Ti,Hf)Mn 2 phase was confirmed at three different temperatures. • The thermodynamics data were built and optimized for this system. [ABSTRACT FROM AUTHOR]

Abstract: Glass-forming ability/range of the Cu–Zr–Ni ternary system was studied by thermodynamic calculations and ion beam mixing of multilayered films. Thermodynamic calculations located an energetically favored composition region for metallic glass formation, and also characterized the composition dependence of the glass-forming ability. Under the guidance of the thermodynamics calculations, four sets of nano-sized Cu–Zr–Ni multilayered samples were designed, prepared and then subjected to irradiation by 200keV xenon ions. It turned out that unique amorphous phases were indeed obtained in the samples Cu21Zr55Ni24 and Cu24Zr45Ni31 that were located in the predicted superior glass-forming ability region, while for the Cu33Zr17Ni50 and Cu68Zr19Ni13 samples that fell within the low glass-forming ability region, ion beam mixing resulted in the formation of amorphous-crystalline dual-phase structures. A brief discussion was also presented for the formation mechanisms of the amorphous phase and the amorphous-crystalline composites. [Copyright &y& Elsevier]