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In this study, we investigated the microstructure, mechanical properties, and thermal performance of Sn-xBi-1Ag (x = 35, 37, 45, and 47 wt.%) solders, with a particular focus on the effect of adding trace Si atoms. The impact of different Ag concentrations on the properties of Sn-xBi-Ag-0.5Si solders was also studied. The results indicated that as the amount of Bi added to Sn-xBi-1Ag solder alloys increased, the tensile strength, microhardness, melting temperature, and melting range decreased somewhat, but the wettability improved. The Cu6Sn5 layer between the soldering alloy and the Cu substrate became thinner upon increasing the Bi content. Adding microcrystalline Si atoms to the Sn-Bi-1Ag alloy improved the tensile strength and microhardness, but the melting point and melting range were not significantly changed. The wettability was optimized, and the diffusion layer formed with the Cu matrix was significantly thinner. By increasing the Ag content in the Sn-Bi-(1,3)Ag-0.5Si alloy, the tensile strength of the alloy was continuously strengthened, while the hardness decreased slightly and the melting point and melting range increased slightly. The wettability was greatly improved, and the Cu6Sn5 layer became thinner.

The 800 °C isothermal section in the Al-Zn-Zr system was investigated using the equilibrated alloy method and the solid/liquid diffusion couple approach by means of scanning electron microscopy equipped with energy dispersive spectroscopy, X-ray powder diffraction and electron probe microanalysis. Thirteen three-phase regions are experimentally confirmed in the ternary system. A ternary compound Zn50Al25Zr25 named as T phase exists stably in the 800 °C isothermal section. Its composition range varies widely (16.84-55.1 at.% Zn, 18.02-56.3 at.% Al and 26.0-28.53 at.% Zr), and it can be in equilibrium with all the binary compounds. The maximum solubilities of Zn in Zr3Al, Zr2Al, Zr3Al2, Zr4Al3, ZrAl, Zr2Al3, ZrAl2 and ZrAl3 are 7.5, 0.84, 0.33, 0.89, 0.91, 1.12, 0.64 and 3.8 at.%, respectively. The maximum solubilities of Al in Zn3Zr, Zn2Zr and ZnZr are 1.6, 1.3 and 13.6 at.%, respectively.

The 600 °C and 450 °C isothermal sections of the Co-Cu-Zn ternary system have been investigated experimentally by means of scanning electron microscopy coupled with energy dispersive x-ray spectroscopy, and x-ray diffraction. Five three-phase regions were confirmed in the 600 °C isothermal section and six three-phase regions existed in the system at 450 °C. The γ-Co5Zn21 and Γ-Cu5Zn8 phases formed a continuous solid solution, which is designated as the γ/Γ phase. No ternary compound was found in the present work. The solubility of Co in δ and β is up to 1.8 and 8.8 at% respectively, and the maximum solubility of Cu in γ1 and β1 is 14.7 and 7.9 at% respectively at 600 °C. The maximum solubility of Co in e and β ´ is 8.5 and 6.7 at% respectively, and the solubility of Cu in γ2, γ1 and β1 is up to 12.9, 14.4 and 11.2 at% respectively at 450 °C.

The isothermal sections of Al–Fe–Sn ternary system at 973 and 593 K were determined experimentally by the equilibriated alloy method using scanning electron microscopy coupled with energy-dispersive spectrometry and X-ray diffractometry. Experimental results show that no ternary compound is found on these two sections. The maximum solubility of Fe in the liquid phase is 1.6% (mole fraction) at 973 K and those of Fe and Al in the liquid phase are 0.6% and 5.1% (mole fraction) at 593 K, respectively. The maximum solubility of Sn in the Fe–Al compounds is 4.2% (mole fraction) at 973 K and 2.3% (mole fraction) at 593 K. All the Fe–Al compounds can be in equilibrium with the liquid phase.

The influence of vanadium on Fe–Al interface reaction of steels during hot-dip process was investigated by immersing low carbon steel plates into six different Al and Al–Zn baths at 730 °C and 620 °C. The microstructure and phase constituent of the formed coatings were analyzed with SEM–EDS and XRD. The intermetallic layers formed on the steel plate surfaces in Al bath consist of Fe2Al5 and FeAl3 phases. As 0.05 wt.% V was added to the Al bath, the Fe2Al5 layer became thinner. Whereas the steel plates were immersed into 55%Al–Zn bath, a periodic laminar structure, containing FeAl3 and Al–Zn phases, formed. However, the periodic laminar structure disappeared and a continuous thin Fe2Al5 layer appeared as V was added into Galvalume bath, and the whole intermetallic layer consists of Fe2Al5, Fe2Al8Si and FeAl3 phases. The presence of 0.05 wt.% V in the bath promoted the formation of Fe2Al5 layer. As it covers the whole steel plate surface, it retards the further Fe–Al reaction in the bath, leading to a thin intermetallic layer. The influence of V on Fe–Al interface reaction was studied by means of Vienna Ab-initio Simulation Package (VASP) based on first-principles method. The exchange energy, bonding energy, charge density differences and electronic density of states of Fe2(Al,V3)5 and Fe(Al,V12)3 are analyzed. Both the experimental results and theoretical calculation results show that V could occupy the vacancies of Fe2Al5 lattice which could promote the nucleation of Fe2Al5, and therefore it suppresses the growth of Fe–Al phase.

The effects of sulfate-reducing bacterial (SRB) on mechano-chemical effect were usually neglected in many literatures. In the paper, the effects of strain, strain rate and SRB physiological activity on mechano-chemical effect of X80 steel were investigated via dynamic tensile testing. The results indicated that SRB physiological activity, the increasing strain and strain rate enhanced individually the mechano-chemical effect. SRB physiological activity and stress synergistically promoted the mechano-chemical effect, while no interaction was observed between SRB physiological activity and strain rate. The local corrosion and sulfide were two main reasons for the increasing mechano-chemical effect in the SRB-inoculated soil solution.

Phase equilibria of the Cu-Sn-Bi ternary system have been investigated by means of x-ray diffraction, scanning electron microscopy and energy-dispersive spectrometry analysis. Cu-Sn-Bi alloys were prepared and equilibrated at 250, 450 and 700 °C, and the equilibrium phases were experimentally identified. Isothermal sections at these three temperatures were proposed based on the experimental results and the information on the three constituent binary systems. Moreover, the solubility of the Bi in the Cu-Sn compounds is less than 0.8 at%. No ternary compound was found. The phase equilibria between the liquid and the solid phases appears to be inclined towards the Bi-corner at all temperatures.

The density of a molten alloy can be calculated from the quotient of its molar mass divided by its molar volume. The molar volume of a molten alloy, however, often deviates from the average of the molar volumes of its constituents. The deviation is caused mainly by the affinity (or lack of it) between dissimilar atoms, which can be quantified by the enthalpy of mixing. Up to now, the link between the enthalpy of mixing and the volume change has been determined empirically through the regression of experimental measurements of alloy densities. In the present study, the derivative of molar volume with respect to enthalpy was deduced and the molar volumes of molten alloys were computed entirely based on the properties of pure elements and the enthalpy of mixing of the alloys. The very slight increase in the packing density due to the size difference of different atoms was also considered. The effect of cluster formation due to short range ordering was also addressed. Over six hundred data points were used in validations. Excellent agreements were achieved between the calculated values and the experimental measurements.

The equilibrated alloys approach was adopted to determine the phase relations of the Zn-Bi-Co ternary system at 450 and 600 °C. The specimens were investigated by means of optical microscopy, scanning electron microscopy/energy-dispersive spectrometry analysis and x-ray diffraction. The experimental results show that five three-phase regions exist in the isothermal section at 450 °C and three tri-phase regions at 600 °C. Bi is almost insoluble in Co-Zn intermetallic compounds; its solubility in α-Co is less than 0.4 at.%. The solubility of Co in the L-Bi phase increases with temperature, the maximum solubility reaching 0.8 at.% at 450 °C and 1.7 at.% at 600 °C.

The phase equilibria of the 700 °C isothermal section of the Al–Si–Fe–Cr quaternary system with Al fixed at 90 at.%, and the related Al-rich ternary systems, have been determined experimentally with scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray diffractometry. Eight four-phase regions and a new quaternary compound named ζ are found in the 700 °C isothermal section of Al–Si–Fe–Cr quaternary system. The ζ phase is found to be in equilibrium with all phases in the section including the FeAl3, τ5, τ6, (Si), τ1, Al4Cr, Al45Cr7 and H phases, as well as the liquid phase.

Phase equilibria in the isothermal section of the Al-Fe-Si-V quaternary system with Al being fixed at 85 wt.% and the Al-rich corner of Al-Fe-Si ternary system at 620 °C have been determined experimentally using scanning electron microscopy coupled with energy dispersive x-ray spectroscopy, and x-ray diffractometry. Five four-phase regions are identified in the isothermal section of Al-Fe-Si-V quaternary system. Five three-phase regions are found in Al-rich corner of Al-Fe-Si ternary system. No new ternary and quaternary compounds are detected in the present study.

The 600 °C isothermal section of the Al-Zn-Ce-Fe quaternary system with Al being fixed at 75 at.% has been studied experimentally by means of scanning electron microscopy coupled with energy dispersive x-ray spectroscopy and x-ray powder diffraction. Four four-phase regions have been identified in this section, namely, τ2+Liq.+α-Al+FeAl3, τ2+Ψ+α-Al+FeAl3, τ2+Ψ+α-Al+αAl11Ce3, τ2+Ψ+αAl11Ce3+αAl3Ce. One Al-Ce-Fe ternary phase Ψ (CeFe2Al10) and another Al-Zn-Ce ternary phase τ2 (Al2Zn2Ce) has been found in this section but no quaternary compound has been found.

Isothermal sections of the Ag–Zn–Ce ternary system in the Ce-poor regions (Ce concentrations below to 33.3 at.%) at 450 °C and 600 °C are determined experimentally using the equilibrated alloy approach. Thirteen three-phase regions have been confirmed at 450 °C and 600 °C, respectively. No ternary compound has been found in this work. Experimental results indicate that the soild solubilities of Ce in the Ag–Zn binary compounds, e.g. β(AgZn), γ(Ag 5 Zn 8 ) and e(AgZn 3 ), are negligible, while that of Zn in Ag 4 Ce and Ag 51 Ce 14 are 32.5 and 44.1 at.% at 450 °C as well as 33.3 and 44.8 at.% at 600 °C, respectively. The solid solubilities of Ag in Zn 3 Ce, Zn 11 Ce 3 , Zn 58 Ce 13 , Zn 5 Ce, Zn 22 Ce 3 , Zn 17 Ce 2 and Zn 11 Ce are 0.1, 2.1, 33.2, 7.7, 9.7, 48.2 and 23.1 at.% at 450 °C, respectively, while the solid solubilities of Ag in the Zn–Ce binary compounds mentioned above are 1.5, 6.1, 40.1, 8.2, 18.5, 50.7 and 25.8 at.% at 600 °C, respectively. In addition, Ag 2 Ce and Zn 2 Ce are combined as (Ag,Zn) 2 Ce because of their continuous solubility.

The 700°C isothermal section of the Fe–Cr–Si ternary phase diagram has been determined experimentally by means of scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray powder diffraction. Ten three-phase regions exist in the 700°C isothermal section. The binary σ phase contains 0–17.6 at.% Si and 31.4–59.2 at.% Cr; the Fe5Si3 phase is stable at 700°C because of the dissolution of Cr. At this temperature, Fe and Cr cannot be entirely substituted by each other to form the FeSi or CrSi phases: the maximum possible Cr content in FeSi2, Fe5Si3 and D03 is 3.9, 20.7 and 15.2 at.%, respectively, and the maximum soluble Fe in CrSi2, Cr5Si3 and Cr3Si is 2.5, 20.4 and 16.8 at.%, respectively.

The 450 °C isothermal section of the Fe-Si-Ti-Zn quaternary system with Zn being fixed at 93 at.% was determined experimentally by means of scanning electron microscopy coupled with wave dispersive x-ray spectroscopy, and x-ray powder diffraction. Fourteen four-phase regions were confirmed experimentally in this isothermal section. The Fe-Ti-Zn ternary phase T-TiFe2Zn22 was found to be in equilibrium with the liquid, ζ-FeZn13, τ2-FeTiSi, and TiZn16 phases. The maximum solubility of Zn in τ2-FeTiSi is 2.74 at.%, but less than 1.08 at.% in τ1-FeTiSi2. Si solubility in T-TiFe2Zn22 is 0.31 at.%, but it is negligible in ζ-FeZn13. The solubility of Ti in the liquid phase is limited. The results of present work are consistent with the relevant ternary systems. No true quaternary compound was found in the isothermal section.

The isothermal section of Al–Cr–Si system at 700 °C was determined by means of scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray powder diffraction. In the 700 °C isothermal section, fourteen three-phase regions exist, three ternary compound named τ 1 , τ 2 and τ 3 are confirmed to be stable and the Al 11 Cr 2 phase is not observed in this section. The solubility of Si in AlCr 2 is relatively low in the Al–Cr–Si system, but the CrSi 2 phase possesses a relatively high solubility of Al. The maximum Al solubility in CrSi 2 , CrSi and Cr 5 Si 3 at 700 °C reaches 25.9, 3.5 and 9.0 at.%, respectively.

The evaluation of ecosystem service value is a focus issue in the construction of ecological civilization in China. With the progress of human civilization, various types of land use projects are increasing day by day, which not only bring huge economic benefits, but also profoundly affect the regional land use pattern and ecological process, and have many influences on ecosystem services. In order to understand the real economic cost of land use projects, it is urgent to evaluate the ecosystem service cost of specific land use projects. In this paper, an ecological service evaluation model for comprehensive evaluation of land use project ecological service value is established. In this model, the emerging theory, virtual disposal cost method and market price method are applied to quantify the ecosystem service cost of land use project from four aspects of water, land, gas and biology. Using our model, we can estimate the ecological cost of a land use project more quickly and obtain the real economic cost of the project. Taking a thermal power plant as an example, the annual cost of the system service is calculated based on the ecosystem evaluation model and the existing model. By comparing the results of the two models, the feasibility and validity of the model are revealed.

The 450 °C isothermal section of the Zn-Fe-Al-Sb quaternary system with Zn fixed at 93 at.% has been studied experimentally using x-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy. The (L + AlSb) field is in equilibrium with other phase fields in the section, except those near the 93Zn7Fe corner. The solubility of Sb in ζ, δ, T, Fe2Al5, and FeAl3 phases is very limited. The Zn-Fe-Al ternary phase T (Al6Fe8Zn86) was found to be in equilibrium with L, δ, Fe2Al5, and AlSb phase. The maximum solubilities of Zn in AlSb, Fe2Al5, and FeAl3 are 5.3, 12.3, and 6.2 at.% respectively. Zn can be dissolved in all compounds existing in the equilibrium alloys. Five four-phase regions and four three-phase regions have been confirmed experimentally.

The isothermal sections of Zn–Fe–B ternary system at 600 °C and 450 °C have been determined experimentally using scanning electron microscopy, electron probe microanalysis and X-ray diffraction. Five three-phase regions exist in the isothermal section at 600 °C, seven three-phase regions exist at 450 °C. The experimental results indicate that B is almost insoluble in Fe–Zn compounds and α-Fe. The solubility of Zn in Fe2B and FeB at 600 °C is 1.8 at.% and 2.5 at.%, respectively, and that at 450 °C is 1.7 at.% and 2.1 at.%, respectively. All Fe–Zn compounds can be in equilibrium with Fe2B, the equilibrium between FeB and ζ prohibits the coexistence of Fe2B and liquid at 450 °C. Both FeB and Fe2B are in equilibrium with the liquid phase at 600 °C.

The 900 °C isothermal sections of the Fe-Cr-Ni-Al quaternary with Fe fixed at 70 at.% and that with Ni fixed at 60 at.% have been determined by scanning electron microcopy coupled with energy dispersive spectroscopy and x-ray diffraction. Only one three-phase region marked as α-Fe + β-(Fe,Ni)Al + γ-Fe has been found in the 70Fe-Cr-Ni-Al section. With regard to the Fe-Cr-60Ni-Al section, there are three three-phase regions, i.e., α-Cr + γ-Ni + γ′-Ni3Al, γ-Ni + γ′-Ni3Al + β-(Fe,Ni)Al and α-Cr + β-(Fe,Ni)Al + γ′-Ni3Al and one four-phase region, namely α-Cr + β-(Fe,Ni)Al + γ-Ni + γ′-Ni3Al. No quaternary compound is found in the present work.

The 450 °C isothermal section of the Fe-Al-Sb ternary phase diagram has been determined experimentally using scanning electron microscopy coupled with energy dispersive x-ray spectroscopy, and x-ray diffraction. No ternary compound is found in this system at 450 °C. Experimental results indicate that Sb cannot dissolve in the Fe-Al compounds, e.g. FeAl2, Fe2Al5, and FeAl3. While the maximum solubilities of Al in FeSb and FeSb2 are 3.2 and 1.3 at.%, respectively, and 0.5 at.% Fe is detected in AlSb.

The effect of Si on the growth kinetics of intermetallic compounds during the reaction of solid iron and molten aluminum was investigated with a scanning electron microscope coupled with an energy dispersive X-ray spectroscope, and hot-dip aluminized experiments. The results show that the intermetallic layer is composed of major Fe2Al5 and minor FeAl3. The Al−Fe−Si ternary phase, τ1/τ9, is formed in the Fe2Al5 layer. The tongue-like morphology of the Fe2Al5 layer becomes less distinct and disappears finally as the content of Si in aluminum bath increases. Si in the bath improves the prohibiting ability to the growth of Fe2Al5 and FeAl3. When the contents of Si are 0, 0.5%, 1.0%, 1.5%, 2.0% and 3.0%, the activation energies of Fe2Al5 are evaluated to be 207, 186, 169, 168, 167 and 172 kJ/mol, respectively. The reduction of the activation energy might result from the lattice distortion caused by Si atom penetrating into the Fe2Al5 phase. When Si atom occupies the vacancy site, it blocks easy diffusion path and results in the disappearance of tongue-like morphology.

The 450 °C isothermal section of the Al-Co-Zn ternary system was determined experimentally by means of scanning electronic microscopy coupled with wave dispersive x-ray spectroscopy, and x-ray powder diffraction. Nine three-phase regions have been confirmed experimentally. The liquid phase is in equilibrium with all Al-Co compounds except Al3Co. The maximum solubility of Zn in AlCo, Al5Co2, Al9Co2 and Al13Co4 is 8.76, 18.14, 1.24, 8.97 at.%, respectively. The Al solubility in the Co-Zn compounds (γ2, γ1, γ, β1) is very small, no more than 0.14, 0.28, 0.32, and 0.62 at.%, respectively. No true ternary compound was found in the present study.

The 600 °C and 750 °C isothermal sections of the Zn–Bi–Ni ternary system have been determined experimentally using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray diffraction. Three three-phase regions exist in the isothermal section at 600 °C and 750 °C, respectively. The Ni–Zn phases are all in equilibrium with the liquid phase in these two isothermal sections. There is a four-phase equilibrated reaction occurred between 450 °C and 600 °C, namely β1 + NiBi ⇔ L + α-Ni, but more experimental works are needed for obtaining the accurate equilibrated reaction temperature. Experimental results show that Bi is almost insoluble in any Ni–Zn compounds and α-Ni. The solid solubility of Zn in the NiBi phase is also limited.

By X-ray diffraction combined with Rietveld structure refinement, the crystal structure of FeZn13 was determined experimentally in this study. The results indicated that the structure of FeZn13 is monoclinic and the lattice parameters are a = 1.3408 nm, b = 0.7605 nm, c = 0.5074 nm, and β = 127.206°. It was confirmed that Fe atoms occupy the 2c position (0, 0, 0.5) in space group C2/m, and the coordinates of Zn atoms at the Zn(1) position are (0.114, 0.5, 0.293), which supports the results from Belin et al. (Acta Cryst. C 56:267, 2000). In addition, an atomistic calculation was carried out to determine the crystal structure based on the interatomic potentials obtained using the lattice inversion method, and Fe atoms are substituted by Zn atoms in the narrow solubility range of FeZn13, which is the fundamental for studying the solubility and site preference of alloying elements of FeZn13. Good agreement between the experimental results and the theoretical calculations was achieved.

The isothermal section of the Zn-Bi-Ni ternary system at 450 °C was determined experimentally using the equilibrated alloys approach. The specimens were investigated by means of optical microscopy, scanning electron microscopic/energy-dispersive spectrometric analysis and x-ray diffraction. Six three-phase regions exist in this isothermal section. The L-Bi phase is in equilibrium with all phases of Ni-Zn binary system except the α-Ni phase. Experimental results indicate that the third element, Zn or Bi, is almost insoluble in the Bi-Ni or Ni-Zn intermetallic compounds.

The online version of the original article can be found under doi:10.1007/s11669-013-0223-4.Tian Hou, Zhongxi Zhu, Yuliang Zhao, Fucheng Yin, Zhi Li, andYongxiong Liu, Key Laboratory of Materials Design and PreparationTechnology of Hunan Province, School of Mechanical Engineering,Xiangtan University, Hunan 411105, People’s Republic of China.Contact e-mail: Zzx552@xtu.edu.cn.