bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fabrication and electrical sliding wear of graphitic Cu–Cr–Zr matrix composites
Authors: Zhan Yongzhong , Zeng Jianmin 
Published: December 2013

Abstract
The present work was undertaken to prepare graphitic Cu–Cr–Zr matrix composites in order to develop new materials for application under sliding contact in an electrical field. The electrical sliding wear behavior of the graphite (Gr)/CuCrZr composite was investigated from a microstructural viewpoint, compared with the matrix alloy. The results indicate that by using the water atomized Cu–Cr–Zr powder and copper-coated graphite particles as starting materials, compact and homogeneous microstructure can be obtained in the composites. Fine and coherent particulate precipitations are formed in the Cu–Cr–Zr matrix during the aging treatment process, which help to improve the mechanical properties. Under the electrical sliding wear condition, incorporation of graphite in the Cu–Cr–Zr matrix not only decrease the wear loss of the sliding pair but also maintain steady-state friction coefficient. The main reason is that the graphite film that smears on the contacting surfaces can alleviate materials loss induced by electric arc discharge and adhesion wear. Proper aging treatment helps to make full use of the solid lubricant effect of the graphite particles.
Influence of Sb additions on surface tension and density of Sn–Sb, Sn–Ag–Sb andSn–Ag–Cu–Sb alloys: Experiment vs. modeling
Authors: Moser Z. , Gąsior W. , Pstruś J. , Ohnuma I. , Ishida K. 
Published: December 2013

Abstract
Surface tension and density measurements by maximum bubble pressure and dilatometric techniques were carried out in an extensive range of temperature on liquid alloys close to the ternary eutectic Sn3.3Ag0.76Cu with different Sb content. It has been found that the addition of Sb to Sn, Sn–Sb, to binary eutectic Sn–Ag and to Sn3.3Ag0.76Cu decreases the surface tension and density. The values of the surface tension calculated by the Butler model and by the method based on the binary alloys surface tension data with the ternary and quaternary correction factors were compared with the experimental results. The best agreement between the measured and the calculated values was observed for the model comprising the binary data with the correction factors.
Development of long-period ordered structures during crystallisation of amorphous Mg80Cu10Y10 and Mg83Ni9Y8
Authors: Garcés G. , Pérez P. , González S. , Adeva P. 
Published: December 2013

Abstract
The different transformations occurring during the crystallisation of amorphous Mg80Cu10Y10 and Mg83Ni9Y8 alloys have been elucidated. The formation of several unknown metastable phases was observed. The present work confirms that such phases exhibit long-period structures originated by the periodic alignment of (Y,TM)-layers (TM: transition metal). The long-period stacking-ordered phase, identified in the crystallised Ni-containing alloy, is stable at higher temperatures than that in the Cu-containing alloy.
Thermodynamic properties and phase relations of Zn-rich alloys in the system Pt–Zn
Authors: Huang Yongzhang , Richter Klaus W. , Yuan Wenxia , Qiao Zhiyu , Ipser Herbert 
Published: December 2013

Abstract
Zinc vapor pressures over binary Pt–Zn alloys were determined in the composition range from 63 to 84 at.% Zn for temperatures between 840–1150K using an isopiestic method. The phase boundaries of four different phase fields in this composition range could be fixed based on the experimental data. Thermodynamic activities and partial molar enthalpies of zinc within these phase fields were derived from the vapor pressure data and the composition dependence of the zinc activity was calculated for 1023 K. The integral Gibbs energy at 1273 K was derived as a function of composition by Gibbs–Duhem integration, combining the activity data of the present investigation with earlier results from the literature.
Metastable phases and nanocrystalline-forming ability (NFA) of melt-quenched Ni-rich (Zr,Hf)–Ni alloys
Authors: Bakonyi Imre 
Published: December 2013

Abstract
In this paper, the basic principles of and some recent advances in rapid solidification are briefly considered, with main emphasis on the formation of single-phase metastable states during meltquenching in Ni-rich Zr–Ni and Hf–Ni alloys. Factors controlling nanocrystalline-forming ability are discussed in detail, with particular view on the preparation of single-phase nanocrystalline alloys by the meltquenching process.
Three-dimensional printing of TiAl3/Al2O3 composites
Authors: Yin Xiaowei , Travitzky Nahum , Melcher Reinhold , Greil Peter 
Published: December 2013

Abstract
Intermetallic/ceramic composites were fabricated by reactive infiltration of an Al melt into a porous TiO2 preform which was prepared by indirect three-dimensional printing. At 1450°C the highly negative Gibbs energy of reaction (Gr=–279.950kJ/mol) is the driving force for the redox reaction 13/2 Al+3/2 TiO23/2 TiAl3+Al2O3 to take place. Wetting of molten Al on the preform surface was improved by adding a carbon-bearing binder ((C6H10O5)n, dextrin) to the powder blend, which decomposed to amorphous carbon (carbon yield 25wt.% of initial dextrin weight) after being heat-treated up to 800°C in an inert atmosphere. During annealing to 1400°C, carbon partially reduced TiO2 at least on the surface of the grains to form Ti3O5 and Ti2O3, which exhibit a significantly lower wetting angle compared to TiO2. In a low-oxygen-containing inert atmosphere and at 1200°C, Al melt spontaneously penetrated into the printed preform via inter-agglomerate pores (mean size 8lm) and intra-agglomerate pores (mean size 1lm). A fine-grained TiAl3/Al2O3 composite microstructure was produced with a residual porosity of 9%.
Re-optimization of the Mg–Sb system under topological constraints
Authors: Malakhov Dmitri V. , Balakumar Thevika 
Published: December 2013

AbstractNon-existing inverted miscibility gaps in the liquid phase at high temperatures, reappearance of the liquid phase at low temperatures or reappearance of a solid phase at elevated temperatures, and other “approximation phantoms” sometimes result from thermodynamic assessments. A method for struggling against such artifacts is proposed. The method is based on introducing a sufficiently dense mesh of knots (not related to experimental points utilized in the optimization) and ensuring that specific inequality conditions (topological constraints) governing the appearance of the phase diagram are satisfied in these knots. It is shown that the syntax of the language describing conditions and experiments in the PARROT module of Thermo-Calc is suitable for performing such optimization. The workability of the approach proposed is exemplified by carrying out a re-optimization of the Mg–Sb system.
Thermodynamic description of the Ni–Si–Ti ternary system
Authors: Du Yong , He Cuiyun , Schuster J. C. , Liu Shuhong , Xu Honghui 
Published: December 2013

Abstract
A thermodynamic modeling of the Ni–Si–Ti system is conducted. All of the experimental phase diagram data available from the literature are critically reviewed and assessed using thermodynamic models for the Gibbs energies of individual phases. The thermodynamic parameters for five ternary compounds (τ1: Ti1Ni1Si1, τ2: Ti4Ni4Si7, τ3: Ti13Ni40Si31, τ4: Ti6Ni16Si7, and τ5: Ti2Ni3Si1), the ternary solution phases (liquid, bcc_A2, bcc_B2, fcc_A1, and L12) as well as the binary phases (Ti5Si3, Ni3Si, Ni5Si2, and TiNi3) showing noticeable solubilities for the third element are adjusted in the optimization. The order/disorder transitions between disordered bcc_A2 and ordered bcc_B2 phases as well as between disordered fcc_A1 and ordered L12 phases are treated using a two-sublattice model. The calculations indicate that the disordered and ordered phases can be described with a single equation. Comprehensive comparisons between the calculated and measured phase diagrams show that in the measured isothermal sections at 750°C, 900°C, 1000°C and 1100°C, most of the observed primary phase regions, as well as 16 out of the 26 experimentally observed invariant reaction temperatures are satisfactorily accounted for by the thermodynamic description. The liquidus projection and reaction scheme for the entire system are also presented. Further experimental work to solve a few discrepancies between calculation and experiment is emphasized.
Gas-phase surface alloying under “kinetic control”: A novel approach to improving the surface properties of titanium alloys
Authors: Ernst F. , Michal G. M. , Oba F. , Liu L. , Blush J. , Heuer A. H. 
Published: December 2013

Abstract
A novel process, “nitridation under kinetic control of the nitrogen activity”, has been developed for diffusing substantial amounts (≍10at.%) of interstitially dissolved nitrogen into the surface of Ti alloys (Ti–6Al–4V). By operating with a gas phase providing a very small, controlled nitrogen activity, this process generates a homogeneous Ti–N solid solution, free of detrimental titanium nitride precipitates, in which the nitrogen concentration smoothly decreases from the surface towards the interior. The process is conformal (applicable to workpieces of arbitrary shape) and provides a substantial (about twofold) increase in surface hardness. The hardened surface layer appears to possess adequate ductility for many structural applications. The concept of “surface alloying under kinetic control” is very general and may also serve to generate well-controlled surface concentration profiles of carbon or oxygen in Ti-base and other structural alloys.
The sintering mechanism and microstructure evolution in SiC–AlN ceramics studiedby EFTEM
Authors: Huang Rong , Gu Hui , Chen Zhongming , Tan Shouhong , Jiang Dongliang 
Published: December 2013

Abstract
The microstructures of three hot-pressed SiC ceramic materials with 5vol.%, 10vol.%, and 15vol.% AlN were investigated by analytical electron microscopy, especially electron energy-loss spectroscopic mapping (EELS mapping). AlN additives dissolve into SiC to form a core/rim structure and to refine the SiC grains. The crystallographic configurations for cores revealed by EELS mapping elucidate the sintering mechanism as liquid-phase sintering in the SiC–AlN composites. The additional 0.5wt.% Y2O3 additives that distribute in the intergranular regions facilitate the formation of liquids to improve the sintering property. With the increase of AlN, the microstructure evolution experienced three stages characterized as solid solution with core/rim structure for a few elongated grains, core/rim for the general equiaxed grains, and the emergence of individual AlN grains with SiC-rich precipitations, respectively. The refined grains and a variety of microstructures contribute to an excellent combination of mechanical properties, with the flexural strength as high as 1000MPa while the fracture toughness remains moderately high.
Electroless deposition of brushite (CaHPO4 · 2H2O) crystals on Ti–6Al–4V at room temperature
Authors: Tas A. Cuneyt 
Published: December 2013

Abstract
An electroless, room temperature solution growth method of depositing 50 to 150 μm thick, well-crystallized brushite (CaHPO4 · 2H2O, DCPD, dicalcium phosphate dihydrate) layers on the surface of an implantable medical device, such as a titanium alloy (Ti–6Al–4V) substrate, was developed. High ionic strength (189 to 609 mM) solutions with a Ca/P molar ratio of 2.50 and a pH value between 4.70 and 6.10 were prepared by dissolving appropriate quantities of CaCl2 · 2H2O, NaH2PO4, NaHCO3, and NaCl in deionized water. Surface-etched Ti–6Al–4V substrates were simply soaked in the solutions from 24 to 72 hours at room temperature. Elongated CaHPO4 · 2H2O crystals were in-situ- grown on the entire surfaces of the etched Ti–6Al–4V substrates.
Thermodynamic analysis of structural transformations induced by annealing of amorphous Si–C–N ceramics derived from polymer precursors
Authors: Golczewski Jerzy Andrzej 
Published: December 2013

AbstractThermodynamic modeling has been used to explain structural transformations induced by heat treatment of amorphous Si–C–N ceramics derived from polymers. Nanocrystalline silicon carbide and nanocrystalline silicon nitride identified in the ceramic microstructure have been regarded as metastable NASIC and NASIN phases in the Si–C–N system. The Gibbs energies G(NASIC) and G(NASIN) have been derived and used together with the previously modeled Gibbs energy of the amorphous am-SICN to compute metastable phase diagrams. Computational results allow explanation of the crystallization process of amorphous Si–C–N ceramics. According to this model, the temperature of invariant reaction between carbon and silicon nitride changes with the growth of nanocrystallites, which explains the dependence of the thermal stability on the ceramic microstructure.
Thermodynamic modelling of the Ce–Ni system
Authors: Pisch Alexander , Wang Jiasong , Jorda Jean-Louis 
Published: December 2013

Abstract
The phase equilibria in the Ni-rich part of the Ce–Ni binary system were re-determined using DTA, metallography and SEM/EDX. CeNi5+x
presents a Ni solubility up to x = 0.53 at 1073K. The melting point of CeNi5 is 1608±5K and the CeNi5+x
–Ni eutectic has been observed at 1477±5K and x(Ni) = 0.91. The enthalpy of formation of stoichiometric CeNi5 has been measured by drop dissolution calorimetry in liquid aluminium and a value of ΔfH = −29.1±2.2kJ/moles of atoms was derived. Based on this new experimental data and literature values, a complete thermodynamic modelling of the Ce–Ni diagram was performed.
Thermodynamic properties of B2-AlFeNi alloys: modelling of the B2-AlFe and B2-AlNi phases
Authors: Oates W. A. , Bencze L. , Markus T. , Hilpert K. 
Published: December 2013

Abstract
Results from our recent simultaneous measurement of all three component activities by Knudsen effusion mass spectrometry, together with results available in the literature from vacancy concentration and calorimetric measurements, have been used in a thermodynamic modelling study. The results of this modelling for the binary B2-AlFe and B2-AlNi phases are presented in this communication. A four-sublattice cluster energy model in the point approximation has been used for the configurational contributions to the Gibbs energy. Excitational free energies are incorporated into the configurational energy and non-configurational contributions are considered to be decoupled from the configurational. The modelling has been found to lead to good agreement between calculated and experimental results for both the thermodynamic properties and the vacancy concentrations. It is clear that B2-AlFe is an antisite defect compound at both the lowest and highest temperatures with vacancy defects only predominating, and to only a small degree, at stoichiometry in an intermediate temperature range. In the case of B2-AlNi, however, vacancy defects predominate at stoichiometry over the whole temperature range so that it can be correctly described as a near-triple defect compound.
The Na–H system: from first-principles calculations to thermodynamic modeling
Authors: Qiu Caian , Opalka Susanne M. , Olson Gregory B. , Anton Donald L. 
Published: December 2013

Abstract
The Na–H system thermodynamic properties were assessed using Gibbs free energy model parameters obtained from best fit optimizations to combined experimental and first-principles predicted data. The first-principles finite temperature thermodynamic property predictions, based upon density functional theory ground state minimizations and direct method lattice dynamics, were used to supplement the Na–H dataset wherever experimental information was unavailable or unattainable. The predictions proved to be important for extending the evaluation of the heat capacity of the stable NaH phase to cover the complete 0–2000K temperature range. The predicted thermodynamic properties of the hypothetical NaH3 end-member representing complete interstitial H substitution in solid body-centered cubic Na, provided a physical basis for modeling H dissolution in the Na lattice. The modeling also showed satisfactory agreement with experimental measurements of NaH enthalpies of formation, NaH decomposition pressures, and H solubility in liquid Na.
Investigation of Cu-graphite composites prepared by electroforming
Authors: Zhao Haijun , Liu Lei , Tang Yiping , Shen Bin , Hu Wenbin 
Published: December 2013

Abstract
In this work, Cu-graphite composites were prepared by electroforming technology in an acidic copper sulfate bath with graphite particles in suspension. The factors affecting the codeposition of graphite particles with copper were studied. At a particle concentration of 20gl−1, a current density of 3Adm−2 and a stirring rate of 100min−1 graphite content in the composites was 21.7vol.%. Microhardness and friction coefficient of the composites decreased with increasing graphite content. However, wear mass-loss decreased, but increased with graphite content above 21.7vol.%. The wear mechanisms of pure Cu and Cu-graphite composites were adhesive wear and delaminating wear, respectively.
Effect of tin added to the zinc bath on the formation and the microstructure of hot-dip galvanized coatings
Authors: Avettand-Fènoël Marie-Noëlle , Reumont Guy , Goodwin Frank , Perrot Pierre , Foct Jacques 
Published: December 2013

Abstract
The present study aims to analyze the effect of tin, added to zinc bath containing aluminium, on the microstructure and on the development of spangles of continuous hot-dip galvanized coatings. Different experimental conditions have been explored and the mechanism of nucleation and growth taking place during the solidification of the coating are discussed with the support of a thermodynamics approach.
Nanoindentation creep and stress relaxation tests of polycarbonate: Analysis of viscoelastic properties by different rheological models
Authors: Schiffmann Kirsten Ingolf 
Published: December 2013

Abstract
Feedback-controlled nanoindentation with a Berkovich diamond tip has been used to perform creep and stress relaxation tests on polycarbonate at room temperature for a wide range of loads (10–30000μN) and indentation depths (30–3000nm). The creep compliance J(t) and relaxation modulus G(t) have been calculated from experimental data as a function of time in the range t = 0.1–100 (1000)s. The data are analysed by different rheological models which are compared: (1) the Burgers model, (2) the generalised Maxwell/generalised Kelvin model, and two empirical approaches: (3) a logarithmic model, and (4) a power law model. The Burgers model gives a poor description of the material behaviour since it assumes a steady-state flow of material which is not observed in the experimental time range. The generalised models yield a set of discrete relaxation- and retardation time constants. It is shown that these time constants do not correlate with specific molecular moving processes in the polymer, but are only one of several possible parameterisations of the creep and relaxation curves. Numerical differentiation of G(t) and J(t) shows that polycarbonate has continuous relaxation- and retardation time spectra, respectively, and the dynamic viscosity (t) of the material increases linearly with time. The behaviour of polycarbonate is best represented by the empirical power law model, which allows optimum fit of creep/relaxation curves, relaxation and retardation time spectra and time-dependent viscosity.
Thermodynamics of high-temperature cuprous sulfide
Authors: Arita Minoru 
Published: December 2013

AbstractPublished measurements of the diatomic sulfur fugacity were used to make a thermodynamic analysis of high-temperature cuprous sulfide between 789K and 1321K. Gibbs–Duhem integration of the fugacity data was used to determine the enthalpy of formation of stoichiometric Cu2S as −123.8kJmol−1. Statistical thermodynamics was applied to find partition functions, interaction energies, and free energies to characterize the configurational aspects of the phase. Theoretical calculations indicated that Cu vacancies might be localized in one half of the Cu lattice sites under quasi-chemical equilibrium.
Effect of LiYO2 addition on sintering behavior and indentation properties of silicon nitride ceramics
Authors: Matovic B. , Rixecker G. , Boskovic S. , Aldinger F. 
Published: December 2013

Abstract
The influence of the sintering additive LiYO2 (5–15wt.%) on sintering behavior, microstructure and mechanical properties of Si3N4 ceramics was investigated. Since LiYO2 enables densification of Si3N4 at extraordinarily low temperatures, sintering was carried out in the range from 1200–1700°C. Densification was found to be enhanced with increasing additive content due to an increasing volume fraction of the liquid. The phase transformation and grain growth occurred through a solution-reprecipitation mechanism, where the precipitation took place preferentially on pre-existing -Si3N4 nuclei (of which the starting powder already contained 20wt.%). The indentation fracture toughness increased with both sintering time and additive content as a result of the growth of elongated grains.
Modelling of metal–mould interface resistance in the Al-11.5 wt.% Si alloy casting process
Authors: Mirbagheri S. M. H. 
Published: December 2013

Abstract
A computational model is developed to include heat transfer, effects of resistance of the metal–mould interface, and pressure in the simulation of the solidification process. The simulation of the interface resistance is based on the Zero Thickness Element, utilizing the Finite Element Method. The solid boundary conditions, including contact resistances, have been modified by a pressure gradient in each of the Zero Thickness Elements. The pressure gradient has been modelled on experimental data. In order to verify the computational results, an Al-11.5wt.% Si alloy has been poured into a permanent mould and the temperature of the interface measured. Then we modelled the effect of metallostatic pressure on the overall heat transfer coefficient in the metal–mould interface. The comparison between the experimental and the simulation results during the solidification process shows a good consistency that confirms the accuracy of the model for the effect of the interface resistance on solidification time.
Thermal residual stress analysis in continuous Al2O3 fiber reinforced NiAl composites
Authors: Chen H. , Hu W. , Atiser A. , Zhong Y. , Gottstein G. 
Published: December 2013

Abstract
Thermal residual stresses (TRSs) in continuous Al2O3 fiber reinforced NiAl composites with and without a BN interlayer were studied by using the finite element method (FEM). The FEM model includes the effect of neighboring fibers of the composite. A minimum sample thickness and a minimum size of the surrounding composite have to be exceeded in order to obtain the correct TRS distribution in simulation. It is shown that the TRS, caused by different thermal expansion of fiber and matrix in the NiAl composite, is sufficiently large to cause fiber damage owing to twinning on different rhombohedral planes in the sapphire fiber. The introduction of a BN interlayer or a higher fiber volume fraction (40–60%) essentially reduces the TRS level in the NiAl composite and lessens the fiber damage. The residual stress in the NiAl composites was experimentally measured by nanoindentation. A good agreement between measurements and finite element analysis was achieved.