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In this study, the Calculation of Phase Diagrams (CALPHAD) method was employed to predict the phase constitution of Sn1Ag.7Cu3Bi x In1.5Sb solder joints with different contents, which also guided the composition ratio of In in the system. Therefore, Sn1Ag.7Cu3Bi x In1.5Sb ( x = 4, 7, 12, 14, 17) solder joints were fabricated and investigated. According to experimental results, In addition could effectively lower the solidus and liquidus temperature supercooling degree of the alloy while increasing its melting range. In could substitute Sn atoms in the Cu6Sn5 phase to form a Cu 6 (Sn, In) 5 phase, and could induce the formation of Ag 2 (Sn, In), Ag 9 In 4 . When the In content exceeds 12 wt.%, the matrix phase γ-InSn 4 phase was formed. Based on the mechanical properties and post-mortem characterization, doping In could significantly ductile the solder joint with limited strength sacrifice, thanks to the increase in the phase volume fraction of the γ-InSn 4 phase. This study provides a viable method to relieve the brittleness of Sn1Ag.7Cu3Bi1.5Sb solder alloy while achieving a lower soldering temperature, which could serve as a guideline for future solder alloy design.

In this study, near-liquidus squeeze casting AZ91D alloy was used to prepare differential support, and the microstructure and mechanical behavior under different applied pressure were investigated. Under the preset temperature, speed, and other process parameters, the effect of applied pressure on the microstructure and properties of formed parts was analyzed, and relevant mechanism was also discussed. The results showed that the ultimate tensile strength (UTS) and elongation (EL) of differential support can be improved by controlling real-time precision of the forming pressure. The dislocation density in the primary phase increased obviously with the pressure increasing from 80 MPa to 170 MPa, and even tangles appeared. When the applied pressure increased from 80 MPa to 140 MPa, the α-Mg grains were gradually refined, and the microstructure changed from rosette to globular shape. With increasing the applied pressure to 170 MPa, the grain could not be further refined. Similarly, its UTS and EL gradually increased with the applied pressure increasing from 80 MPa to 140 MPa. With increasing to 170 MPa, the UTS tended to be constant, but the EL gradually decreased. In other words, the UTS (229.2 MPa) and EL (3.43%) of the alloy reached the maximum when the applied pressure was 140 MPa, and the comprehensive mechanical properties were the best.

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 θ-phase was confirmed to be peritectic. A metastable congruent solidification of the θ-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−1). The temperature stability of the ζ-phase was reevaluated and was found to lie in the range 373–597 °C. The phase boundaries of the γ′ + ε′ two-phase field were experimentally defined. Difficulties in defining the γ′/δ 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 (γ′ + δ) two-phase field was postulated from XRD studies of quenched samples. The temperature of the ordering reaction γ ↔ γ′ within the γ(γ′) + β 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.

Here, a complete phase equilibria picture in the Cu-As-S system was obtained by experimental study of carefully crystallized via long-term thermal annealing alloys by means of methods of differential thermal analysis and powder x-ray diffraction, as well as using the available literature data. The projection of the liquidus surface, the isothermal section at 300 K, and some vertical sections of the phase diagram are presented and discussed. The fields of primary crystallization of phases, types, and coordinates of invariant and monovariant phase equilibria are determined. The presented phase diagram reflects four ternary compounds Cu 3 AsS 4 , Cu 12 As 4 S 13 , Cu 6 As 4 S 9 , and CuAsS, which are synthetic analogues of natural copper-arsenic sulfide minerals. Particular attention is paid to the Cu 2 S-As 2 S 3 section. It is shown that this section, in contrast to the literature data, is not quasi-binary. The thermodynamic data for copper-arsenic sulfides, previously obtained by the authors by the electromotive force method with Cu 4 RbCl 3 I 2 solid electrolyte, have also been revised. Experimental data on the partial thermodynamic functions of copper in some phase regions of the Cu-As-S system were processed taking into account the constructed new version of the solid-phase equilibria diagram and updated data on the standard thermodynamic functions of formation and standard entropies of the ternary compounds Cu 3 AsS 4 , Cu 12 As 4 S 13 , Cu 6 As 4 S 9 , and CuAsS were obtained.

The effects of varying Mg and Si levels on the microstructural inhomogeneity and eutectic Mg2Si morphology in die-cast Al–Mg–Si alloys have been investigated. It was found both Mg and Si additions decreased the microstructural inhomogeneity by producing more well distribution of primary α-Al and Al–Mg2Si eutectics, but had contrary effects on eutectic Mg2Si morphology. The increasing Mg level transformed eutectic Mg2Si from rod or lamellae to curved flake with larger eutectic spacing λ, while the increasing Si level promoted the formation of rod-like or lamellar eutectic Mg2Si with smaller λ. The reason for the above evolutions can be traced back to alloys’ solidification behaviour. Thermodynamic calculation indicates that both Mg and Si decrease the liquidus temperature and suppress the precipitation of coarse primary α-Al grains (which tend to agglomerate in centre zone of samples) during the first solidification in shot sleeve, thus reducing the microstructural inhomogeneity. Mg addition shifts the eutectic point to lower Mg2Si concentration and induces a slower eutectic growth rate, causing a lower Mg2Si volume fraction in Al–Mg2Si eutectic cell. On the contrary, Si addition increased the Mg2Si volume fraction in eutectic cell by raising the Mg2Si eutectic concentration and the eutectic growth rate. To minimize the interfacial energy, Al–Mg2Si eutectics with different Mg2Si volume fractions exhibit various morphologies. The tensile test results show that both Mg and Si improved the strength at the cost of ductility. However, due to the formation of fine Al–Mg2Si eutectics, Si induced less ductility sacrifice than Mg when achieving the same strength improvement.

To determine slag properties and the factors influencing these properties for optimization of operating conditions in the copper flash smelting process, the composition and microstructures of the quenched smelting and converting slags have been analyzed. Thermodynamic software FactSage 8.2 has been used to investigate the effects of matte grade, SO2 partial pressure, and the Fe/SiO2 ratio on the liquidus temperature and the copper content of the smelting slag. The possibility to recover valuable metals from the smelting and converting slags through pyrometallurgical reduction by carbon is also discussed. It was found that the flash smelting slag temperature is usually higher than its liquidus temperature and the copper (1.2% Cu) is mainly present in the slag as dissolved copper. In the copper flash smelting process, the copper content in the slag can be decreased by decreasing the Fe/SiO2 ratio and temperature. In pyrometallurgical slag reduction, most Cu, Mo, and Ni can be recovered as an alloy. The conditions of recovery such as the ratio of smelting slag to converting slag, temperature, and reduction extent have been discussed.

Liquid–liquid transition, a phase transition of one liquid phase to another with the same composition, provides a key opportunity for investigating the relationship between liquid structures and dynamics. Here we report experimental evidences of a liquid–liquid transition in glass-forming La 50 Al 35 Ni 15 melt above its liquidus temperature by 27 Al nuclear magnetic resonance including the temperature dependence of cage volume fluctuations and atomic diffusion. The observed dependence of the incubation time on the degree of undercooling is consistent with a first-order phase transition. Simulation results indicate that such transition is accompanied by the change of bond-orientational order without noticeable change in density. The temperature dependence of atomic diffusion revealed by simulations is also in agreement with experiments. These observations indicate the need of two-order parameters in describing phase transitions of liquids. Non-density driven liquid-liquid transition has been predicted in theories, but direct experimental verification is challenging because liquid often remains metastable at transition temperature. Here, Xu et al. provide evidence in a lanthanum-based metallic glass above its liquidus temperature.

Phase equilibria in the Zr-Ti-Cu system have been studied by differential thermal analysis, scanning electron microscopy, x-ray microanalysis, and x-ray diffraction. Based on the obtained results, a ternary phase diagram was constructed over the entire composition range in the crystallization interval. The results are presented in the form of liquidus and solidus projections, the Scheil reaction scheme, and isopleths for sections of 40 and 70 at.% Cu. Phase equilibria in the system are defined by the ternary compound ZrTiCu 2 (τ 1 ) and the binary-based phase Zr 14 Cu 51 . These phases have the widest fields of primary crystallization on the liquidus projection and form two-phase equilibria with all other phases on the solidus projection. The solidus projection contains 11 three-phase fields. Two of them form by invariant four-phase reactions of the transition type, the rest by eutectic ones. A comparison of the solidus projection with the published isothermal sections at 800 and 750 °C led to the need for two solid-state four-phase invariant equilibria involving binary Ti-Cu intermetallic compounds. They are shown to occur between 840 and 850 °C. The ternary compound Zr 22 Ti 14.5 Cu 63.5 (τ 2 ) was shown to form in the solid state at 827 °C by three-phase invariant reaction τ 1  + Zr 14 Cu 51  ⇄ τ 2 .

This work aims to assess the effect of an oxygen content graded in minimal quantities, on the order of hundreds of ppms, on the determination of surface tension of low-alloy FeCOCr and FeCONi steels in contact with a corundum substrate. Oxygen, as a surface-active element, was segregated at the surface where it interacted with the major components of the alloys, leading to a reduction in surface tension. The sessile drop method was used for wetting tests in the temperature range from steel liquidus temperatures to 1600 °C under nonoxidizing conditions. The effect of oxygen on surface tension and wetting angles was verified by statistical analysis using the Kruskal–Wallis test, which supported the results stating that the values of these quantities decreased with increasing oxygen content. Furthermore, liquidus temperatures, which are of practical importance, were determined by the optical and DTA methods and then compared with theoretically calculated temperature values. It turned out that the increased chromium content causes difficulties in determining surface tension up to 1550 °C due to the formation of a thin Cr2O3 layer. In addition, SEM and XRD analyses accompanied by calculations in the FactSage oxide database were performed to better understand the wetting mechanism.

Interactions of Ag and Sb(III) and Sn(IV) sulfides were investigated by x-ray diffraction, differential thermal analysis and microstructure analysis methods. The quaternary compound Ag 11 Sb 3 SnS 12 was found for the first time in the Ag 2 S-Sb 2 S 3 -SnS 2 system at 500 K (227 °C) at the intersection of AgSbS 2 -Ag 8 SnS 6 and Ag 3 SbS 3 -Ag 2 SnS 3 . The compound melts congruently at 920 K (647 °C) and has a polymorphous transition at 646 K (373 °C). The quasi-ternary system is characterized by solid solution ranges of the binary compounds Ag 2 S, Sb 2 S 3 , SnS 2 , ternary Ag 3 SbS 3 , AgSbS 2 , Ag 8 SnS 6 , Ag 2 SnS 3 and quaternary compound Ag 11 Sb 3 SnS 12 . The separation of the composition triangle into 10 single-phase, 18 two-phase, and 9 three-phase fields was established. Seven vertical sections were investigated of which five are quasi-binary (Ag 3 SbS 3 -Ag 8 SnS 6 , Ag 3 SbS 3 -Ag 2 SnS 3 , AgSbS 2 -Ag 8 SnS 6 , AgSbS 2 -Ag 2 SnS 3 , AgSbS 2 -SnS 2 ). The AgSbS 2 -Ag 4 Sn 3 S 8 and AgSbS 2 -Sb 2 SnS 5 sections are non-quasi-binary due to peritectic formation of Ag 4 Sn 3 S 8 and Sb 2 SnS 5 . The liquidus surface projection of the Ag 2 S-Sb 2 S 3 -SnS 2 system consists of 10 fields of primary crystallization of the solid solutions α-Ag 2 S, β-Sb 2 S 3 , γ-SnS 2 , δ-Ag 3 SbS 3 , ε′-AgSbS 2 , ζ-Ag 8 SnS 6 , η-Ag 2 SnS 3 , σ-Ag 11 Sb 3 SnS 12 and compounds Ag 4 Sn 3 S 8 and Sb 2 SnS 5 . These are separated by curves of monovariant equilibria that converge at 9 ternary invariant points (7 eutectic (E 1 -E 7 ) and 2 quasi-peritectic (U 1 , U 2 )).