Experimental Investigation and Thermodynamic Calculationof the Phase Equilibria in the Cu-Ni-Sb Ternary System

We investigated the phase equilibria in the Cu-Ni-Sb ternary system at 800°C, 900°C, 1000°C, and 1100°C using equilibrated ternary alloys by optical microscopy, electron probe microanalysis, energy-dispersive spectroscopy, and x-ray diffraction analysis. Based on the experimental phase equilibria data, the Cu-Ni-Sb ternary system was thermodynamically optimized by calculating phase diagrams using the CALPHAD method. Substitutional solution and sublattice models were used to describe the solution and intermediate phases, respectively. The self-consistent parameters describing the Gibbs energy of each phase in the Cu-Ni-Sb system were optimized, obtaining reasonable agreement between the calculated results and most of the experimental data.     

Thermodynamic Assessment of Phase Equilibria in the Sn-Ag-Ni System with Key Experimental Verification

The phase transformations of the Sn-Ag-Ni system were investigated by means of differential scanning calorimetry (DSC). Based on the experimental data of phase equilibria and thermodynamic properties determined by the present work and previous literature, the thermodynamic assessments of the Sn-Ag-Ni system were carried out using the calculation of phase diagrams (CALPHAD) method. The thermodynamic parameters for describing the phase equilibria were optimized, and reasonable agreement between the calculations and experimental data was obtained in the Sn-Ag-Ni ternary system.     

Thermodynamic Assessment of the Ni-Bi Binary System and Phase Equilibria of the Sn-Bi-Ni Ternary System

As a basis to understand the interfacial reaction between the Sn-Bi solder and the Ni substrate in electronic packaging, thermodynamic calculations of phase equilibria have been carried out on the binary Ni-Bi system. The Gibbs free energy of the NiBi phase has been approximated, using a three-sublattice model, and thermodynamic parameters have been evaluated, using available experimental information on phase boundaries and other related thermodynamic properties. The calculated phase diagram and thermodynamic quantities of the Ni-Bi binary system showed good agreement with the experimental data. The Sn-Bi-Ni ternary system was calculated using the thermodynamic parameters of the Sn-Bi, Sn-Ni, and Ni-Bi binary systems, and it was compared with experimental measurements.     

Thermodynamic Calculation of Phase Equilibria in the Sn-Ag-Cu-Ni-Au System

Sn-Ag-Cu base solders are the most promising candidates to substitute for Sn-Pb eutectic solder. Gold (Au) coatings are used to protect conductor surfaces from oxidation and thereby to promote solderability, and Ni is often used as a diffusion barrier layer between lead-free solders and substrates to restrict the growth of intermetallic compound layers. In the present work, thermodynamic calculations of phase equilibria in the Sn-Ag-Cu-Ni-Au system, which is of importance for developing lead-free solders, are carried out using the calculation of phase diagrams (CALPHAD) method. Substitutional solution and sublattice models are used to describe the solution and intermediate phases, respectively. Some examples of thermodynamic calculation are presented, and it is shown that the phase diagrams, liquidus projection, and thermodynamic properties can be predicted based on the present calculations.     

Thermodynamic Properties of Liquid Ag-Au-Sn Alloys

The thermodynamic properties of liquid Ag-Au-Sn alloys were studied with an electromotive force (EMF) method using the eutectic mixture of KCl/LiCl as a liquid electrolyte. Activities of Sn in the liquid alloys were measured at three cross-sections with constant molar ratios of Ag:Au = 2:1, 1:1, and 1:2 with tin in the concentration range between 20 at.% and 90 at.% from the liquidus of the samples up to 1030 K. The integral Gibbs energies at 973 K and the integral enthalpies were calculated by Gibbs–Duhem integration.     

Phase Equilibria of the Sn-Bi-Te Ternary System

Bi₂Te₃ is one of the most promising thermoelectric materials, and Sn is the primary constituent of most electronic solders. Knowledge of phase equilibria of the Sn-Bi-Te ternary system is important for thermoelectric applications. Twenty-seven Sn-Bi-Te alloys were prepared and equilibrated at 160°C and 500°C. The equilibrium phases were determined, and the isothermal sections were constructed based on three binary constituent phase diagrams and ternary phase equilibria results. No ternary compounds were observed in the Sn-SnTe-Bi region. The SnTe phase is very stable and has tie-lines with the Sn, liquid, and Bi phases at 160°C. At 500°C, in addition to the already known SnBi₂Te₄ and SnBi₄Te₇ ternary phases, two new ternary compounds (Sn₂Bi₂Te₅ and SnBiTe₂ phases) were found. SnTe and Bi₂Te₃ have significant mutual solubilities, and the ternary compounds SnBi₂Te₄, SnBi₄Te₇, and Sn₂Bi₂Te₅ are all in the SnTe-Bi₂Te₃ pseudobinary section.     

Phase Equilibria of the Sn-Sb Binary System

Sn-Sb alloys are important high-temperature solders. However, inconsistencies are found in the available phase diagrams, and some phase boundaries in the Sn-Sb system have not been determined. Sn-Sb alloys were prepared, equilibrated at 160°C to 300°C, and the equilibrium phases and their compositions were determined. The β-SnSb phase has a very wide compositional homogeneity range, and its composition varies from Sn-47.0at.%Sb to Sn-62.8at.%Sb. There is no order–disorder transformation of the β-SnSb phase. There are three peritectic reactions in the Sn-Sb system, L + Sb = β-SnSb, L + β-SnSb = Sn₃Sb₂, and L + Sn₃Sb₂ = Sn, and their temperatures are 424°C, 323°C, and 243°C, respectively. Thermodynamic models of the Sn-Sb binary system were developed using the CALPHAD approach based on the experimental results of this study and the data in the literature. The calculated phase diagram and thermodynamic properties are in good agreement with the experimental determinations.     

Experimental Studies and Thermodynamic Assessment of Ternary Cu-Pd-Sn Phase Relations Focusing on the Sn-Rich Alloys

Recently, Pd surface finishes over Cu substrates have been widely used in microelectronic packaging to prevent pad oxidation before soldering and to improve the bondability with Cu wires. The interfacial reactions between these newly developed Pd-based substrates and Pb-free solders, particularly Sn-based solders, are of practical importance. To completely understand interfacial reactions and phase transformation phenomena, phase equilibrium information on solders, intermetallics, and substrate materials are required. In this study, the phase equilibria of the Cu-Pd-Sn ternary system at 200°C was investigated by scanning electron microscopy, electron probe microanalysis, and electron backscatter diffraction. Particular emphasis was placed on the Sn-rich corner of the isothermal section. To analyze the experimental results, a thermodynamic assessment was performed using the computer coupling of phase diagrams and thermochemistry method.     

Phase Equilibria in the Sn-Rich Corner of the Ni-Sb-Sn System

Phase equilibria in the ternary Ni-Sb-Sn system are of interest for high-temperature soldering, both considering ternary alloys as solder materials themselves or as the basis for understanding the reactions between Sb-Sn-based solders and Ni-based substrates. Therefore, the Sn-rich corner of the ternary Ni-Sb-Sn phase diagram with Sn content of more than 75 at.% was investigated by a combination of powder x-ray diffraction (XRD), differential thermal analysis (DTA), and electron probe microanalysis (EPMA). Ternary phase equilibria and phase compositions of the respective equilibrium phases were determined within the isothermal section at 200°C, and two isopleths were constructed for constant Sn contents of 80 at.% and 85 at.%. The experiments were supported by CALPHAD-type calculations of this ternary system to yield a consistent reaction scheme which shows four invariant ternary transition reactions in this composition range. A liquidus projection is presented, accompanied by the corresponding Scheil diagram.     

Phase Equilibria in the Ag-Ni-Sn System: Isothermal Sections

The ternary system Ag-Ni-Sn is one of the constituents of the quaternary system Ag-Cu-Ni-Sn, which is of interest for the investigation of the interactions of Ag-Cu-Sn solder alloys with Ni as a substrate. Until now, only limited research has been done on the Ag-Ni-Sn system, especially in the (Ag,Ni)-rich part, most probably due to experimental difficulties caused by the monotectic reaction in the Ag-Ni binary system, which extends far into the ternary. In the present work a comprehensive study of the phase equilibria in four isothermal sections of the Ag-Ni-Sn system at 200, 450, 700, and 1050°C was carried out employing X-ray diffraction (XRD), metallography, and electron probe microanalysis (EPMA). No evidence for the existence of a ternary phase was obtained, and, in most cases, ternary solubilities of the binary phases were found to be insignificant. The liquid miscibility gap at high temperatures caused a number of serious experimental problems during sample preparation.     

Phase Equilibria of the Sn-Ag-Cu-Ni Quaternary System at 210°C

Sn-Ag-Cu alloys are the most promising Pb-free solders, and Ni is a common barrier layer material for the under-bump metallurgy. Although the Sn-Ag-Cu-Ni quaternary system is important for industry, no solid-phase equilibrium information is available. This study determines the equilibrium phase relationship of the Sn-Ag-Cu-Ni system at 210°C. Quaternary alloys are prepared from the pure constituent elements and equilibrated at 210°C. The equilibrium phases formed in the quaternary alloys are determined using scanning electron microscopy, electron probe microanalysis, and x-ray diffraction (XRD) analysis. The quaternary phase relationships are constructed from the quaternary experimental results and the 210°C isothermal sections of the equilibrium phase diagrams of its constituent ternary systems. Two isoplethal sections, 90at.%Sn and 80at.%Sn, of the 210°C phase equilibria of the Sn-Ag-Cu-Ni system are determined. A Cu₆Sn₅ + Ni₃Sn₄ + Ag₃Sn + Sn four-phase region is observed in both isopleths, and no ternary and quaternary intermetallic compounds are found.     

Phase Equilibria of the Sn-V System and Interfacial Reactions in Sn/V Couples

Sn-V alloys were prepared for a phase equilibrium study at 600°C and 250°C. All alloys were annealed for longer than 6 months to ensure that they reached equilibrium. There are two intermetallic compounds, namely VSn₂ (V₂Sn₃) and V₃Sn phases. The composition of the VSn₂ phase is Sn-34.0at.%V. The VSn₂ phase has the CuMg₂ structure. It was previously designated as the V₂Sn₃ phase and was renamed in this study to be consistent with its structure and composition. The composition of the V₃Sn phase is Sn-78.0at.%V, and it has the A15 structure at 600°C and 250°C. With the new experimental results, the Sn-V system has been thermodynamically assessed with the CALPHAD approach. The calculated Sn-V phase diagram is in good agreement with the experimental determinations. Sn/V interfacial reactions at 950°C and 600°C are also examined in this study. The V₃Sn phase is formed at 950°C, while the VSn₂(V₂Sn₃) phase is formed at 600°C.     

几何位相非线性变化的实验研究

本文报道了Pancharatnam位相非线性变化的实验研究，实验结果与理论预言符合得很好。Pancharatnam位相的这种非线性可能在光开关中得到应用。     

非完全相位共轭特性研究

实验研究了部分相位共轭的特性,实验表明非完全相位共轭对相位共轭保真度及相位共轭光的能量集中度具有一定的影响,在没有吸收的情况下,根据能量守恒和互逆原理,推导了相位共轭保真度和相位共轭镜的有限尺寸之间的简单关系。     

Wetting of Cu Pads by Bi-2.6Ag-xCu Alloys and Phase Equilibria in the Ag-Bi-Cu System

The phase equilibrium in the Ag-Bi-Cu system was experimentally determined at 573 K, 773 K, and 973 K by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) on annealed alloys and liquid/solid couples. The experimental results indicate that the mutual solubility of the components is limited. Based on the present results and literature data, phase equilibria in the Ag-Bi-Cu system were thermodynamically assessed. Wetting of Bi-2.6Ag-xCu alloys on Cu substrates was studied with the sessile drop method in the presence of flux at 573 K and 623 K. It was found that the wetting to non-wetting transition corresponds to the solubility limit of Cu in liquid. Selected solidified solder–substrate couples were cross-sectioned and their interfacial microstructure examined with SEM–EDS. There are no reaction products at the interface, but the copper surface becomes rough because of dissolution by liquid solder.     

Investigation of the Phase Equilibria of Sn-Cu-Au Ternary and Ag-Sn-Cu-Au Quaternary Systems and Interfacial Reactions in Sn-Cu/Au Couples

The phase equilibria of the Sn-Cu-Au ternary, Ag-Sn-Cu-Au quaternary systems and interfacial reactions between Sn-Cu alloys and Au were experimentally investigated at specific temperatures in this study. The experimental results indicated that there existed three ternary intermetallic compounds (IMCs) and a complete solid solubility between AuSn and Cu₆Sn₅ phases in the Sn-Cu-Au ternary system at 200°C. No quaternary IMC was found in the isoplethal section of the Ag-Sn-Cu-Au quaternary system. Three IMCs, AuSn, AuSn₂, and AuSn₄, were found in all couples. The same three IMCs and (Au,Cu)Sn/(Cu,Au)₆Sn₅ phases were found in all Sn-Cu/Au couples. The thickness of these reaction layers increased with increasing temperature and time. The mechanism of IMC growth can be described by using the parabolic law. In addition, when the reaction time was extended and the Cu content of the alloy was increased, the AuSn₄ phase disappeared gradually. The (Au, Cu)Sn and (Cu_,Au)₆Sn₅ layers played roles as diffusion barriers against Sn in Sn-Cu/Au reaction couple systems.     

Experimental Assessment of the RESCUE Collision-Mitigation System

Road-traffic-incident analysis has shown that 52% of incidents are caused by a collision between two vehicles or between a vehicle and an obstacle. In this paper, the REduce Speed of Collision Under Emergency (RESCUE) collision-mitigation system (version 1.0) is presented and evaluated toward various typical road situations. The aim of the RESCUE system is to decrease the kinetic energy dissipated during a collision through automatic emergency braking that occurs 1 s before the collision. This emergency braking is triggered by an alarm coming from a decision unit taking into consideration the results of a generic obstacle-detection system-based on fusion between stereovision and laser scanner-and a warning area in front of the vehicle. The different subsystems are presented. Then, the behavior of the RESCUE collision-mitigation system toward various typical dangerous road situations is assessed through systematic tests. These quantitative tests are completed by qualitative ones carried out on 737 km of open roads (freeways, highways, rural roads, downtown) to provide a more precise idea about the false-alarm rate. The experiments show the system is promising in terms of reliability, genericity, and efficiency