Overview Lead-Free SolderThe methods for modeling the thermodynamic properties of multicomponent systems are described in this article. The rules for creating a consistent database for muticomponent systems are described in general terms and documented in relation to the thermodynamic database for lead-free solders, developed within the scope

The phase diagram of the Al-Cu binary system was reinvestigated experimentally. The current study was designed to contribute to a better description of those parts of the phase diagram which are disputed in the current scientific literature, and in addition, to study the phase equilibria at 300°C. The melting behavior of the h-phase was confirmed to be peritectic. A metastable congruent solidification of the h-phase was observed from the microstructural examination of as-cast samples. The location of the liquidus curve in this region of the phase diagram was more accurately defined using DSC measurements taken at slow-heating rates (1°C min À1). The temperature stability of the f-phase was reevaluated and was found to lie in the range 373-597°C. The phase boundaries of the c¢ + e¢ two-phase field were experimentally defined. Difficulties in defining the c¢/d transition were addressed by a combined EDX/XRD investigation of more than ten samples that had been annealed in the temperature range of 500 to 750°C. The (c¢ + d) two-phase field was postulated from XRD studies of quenched samples. The temperature of the ordering reaction c M c¢ within the c(c¢) + b phase field was experimentally determined to be 779.6°C. All other parts of the Al-Cu phase diagram studied here were found to be in very good agreement with the most recent previous descriptions.

SnAg nanoparticles (SnAg NPs) were prepared by wet synthesis. The chemical composition of the SnAg NPs was obtained by inductively coupled plasma - mass spectrometry. The prepared fine powder samples were characterized by electron microscopic technique (SEM) and thermal analysis (DSC). The nanoparticles with different size were obtained. The size dependent melting point depression (MPD) of the SnAg NPs was determined experimentally. The size dependent phase diagram of the SnAg alloy was also calculated using CALPHAD method, which has been extended to describe the surface energy of SnAg nanoparticles. The same approach was used for SnAg eutectic MPD calculations. The own experimental and theoretical results were compared with the data of the other authors. The satisfactory agreement was found

The current state of thermodynamic modelling in the field of high-temperature lead-free soldering is presented. A consistent thermodynamic database, containing 18 elements (Ag, Al, Au, Bi, Co, Cu, Ga, Ge, Mg, Ni, P, Pb, Pd, Sb, Sn, Ti and Zn) has been created. The thermodynamic data for the most of the important binary and selected ternary systems were checked and included into the database. The database was tested using major commercial software packages. Such reliable and sophisticated software coupled to reliable thermodynamic databases are necessary prerequisites for application of thermodynamics in advanced alloys design

International. This e-offprint isExperimental Study of the Sb-Sn-Zn Alloy System ONDREJ ZOBAC, JIRI SOPOUSEK, JIRI BURSIK, ADELA ZEMANOVA, and PAVLA ROUPCOVA The Sb-Sn-Zn alloy was prepared and researched by experimental methods, which allow obtaining information on the thermodynamic stability of the coexisting phases. Thermal analysis was used to determine the phase transition temperatures of experimental alloys. Equilibrium composition of coexisting phases after long-term temperature equilibration was determined by electron microscopy. The existence of one ternary stoichiometric phase Sb 2 SnZn was experimentally confirmed by diffraction technique. The CALPHAD method for prediction of the phase diagram of the Sb-Sn-Zn system from binary subsystems was used in this work.

A method for modelling of size-dependent phase diagrams was developed by combining the semiempirical CALPHAD method and ab initio calculations of surface stresses for intermetallic phases. A novel approach was devised for the calculation of surface energy, free of systematic errors from the selection of different parameters of the software (e.g. number of the k-points) and for handling layered structures and off-stoichiometric slabs. Our approach allows the determination of complex size-dependent phase diagrams of systems with intermetallic phases, which was not possible up to now. The method was verified for the modelling of the phase diagram of the Ni-Sn system and basic comparison with rare experimental results was shown. There is reasonable agreement between the calculated and experimental results. The modelling of size-dependent phase diagrams of real systems allows the prediction of phase equilibria existing in nanosystems and possible changes in material properties. There is a need for such knowledge and the existence of reliable data for simpler systems is crucial for further application of this approach. This should motivate future experimental work.

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