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The article presents a list of papers published in the 2004 and 2005 issues of the "Journal of Materials Science." Some of the papers listed are: "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials"; "Role of Entropy of Fusion in Phase Transformation and Self-Diffusion"; "Models in Thermoluminescence"; "Electrical Applications of Carbon Materials"; "Use of Polymers for Cement-Based Structural Materials"; and "Effect of Anions on the Textural and Catalytic Activity of Titania-Silica Mixed Oxide."

The article presents a list of papers published in the vol. 39 and 40 of the "Journal of Materials Science." Some of the papers are, "Adhesively-Bonded Joints and Repairs in Metallic Alloys, Polymers and Composite Materials," by A. Baldan, "Thermo-Mechanical Fatigue of Shape Memory Alloys," by E. Hornbogen, "Electrical Applications of Carbon Materials," by D.D.L. Chung, and others.

The ordered γ′-(Ni, Cu)3Al is a crucial strengthening phase that improves the high-temperature resistance of Cu-based alloys, so it is important to predict the kinetic evolution of the composition and microstructure of the phase for high-temperature applications. Herein, this paper discusses the temporal evolution of the composition and coarsening of the γ′ phase in a model ternary Cu50Ni37.5Al12.5 (at%) alloy during isothermal aging at 600, 700, 800, and 900 °C for 1–36 h. It is found that the γ′ phase composition evolves linearly toward a binary γ′ phase as the aging time increases during the process of aging at 800 and 900 °C, which cannot be predicted by the ternary phase diagrams alone. Meanwhile, through the utilization of the aforementioned linear law, the γ phase composition can be predicted at a given temperature within the alloy by determining the volume fraction of the γ′ phase. Additionally, the activation energy for coarsening decreases, and the coarsening rate of the γ′ phase increases owing to the higher diffusion rate of Cu at high temperatures. The addition of microalloying elements with strong enthalpic interactions is beneficial for reinforcing the structural stability of the γ′ phase. This work provides a simple method for the compositional analysis and performance prediction of Cu–Ni–Al alloys at elevated temperatures and sheds light on the subsequent compositional design and optimization of Cu-based high-temperature alloys. [ABSTRACT FROM AUTHOR]

Methods of economical alloying of high pipe steels were considered in the paper. Due to the large environmental, energy, and economic issues in the destruction of the pipeline, the quality of steel pipes is very important. The method described in this article is considered to be relevant not only for pipe steels but also for high-strength steels used in shipbuilding, bridge construction, etc. Review mechanisms of strengthening microalloyed steels were carried out in this work. Schema evolution of the microstructure of microalloyed steels was discussed. The influence of alloying elements in steel by means of optimal process parameters of thermomechanical rolling was analyzed. There are two methods of mathematical modeling used in the study: artificial neural networks (ANNs) which are based on the multilayered perceptron to select the optimal chemical composition and finite element analysis to optimize the process parameters. An experimental dataset was used to train multilayer perceptron (MLP) networks to allow for prediction of the yield strength, tensile strength, and elongation of steel. Due to large availability, low cost, and high accuracy of the results, these methods are considered to be the most promising ones. The mathematical model for calculating mechanical properties of a rolling pipe has been developed. Two ways to reduce the cost of a hot-rolled plate made of microalloyed steels were developed. There has been developed the complex of replacement technological impact which can make it possible to replace or reduce the amount of expensive chemical elements (vanadium, nickel, copper, manganese, chromium, and niobium) without loss of quality. [ABSTRACT FROM AUTHOR]

TIMETAL LCB was introduced more than 10 years ago targeting automotive suspension spring applications. The alloy development aim was to use a low-cost formulation by selecting less expensive raw materials than typical beta titanium alloys. Following the first successful application of TIMETAL LCB suspension springs to series production vehicles, the 2000 Volkswagen Lupo FSI, the springs have been used for Ferrari Challenge Stradale since 2003. The most recent development effort was focused on the generation of metallurgical and mechanical service data for the alloy, and the implementation of efficient low cost processing of coils. This paper will introduce various properties of TIMETAL LCB products that can be useful in the design and the consideration of spring applications. Recent progress in the processing of TIMETAL LCB will also be introduced and discussed. [ABSTRACT FROM AUTHOR]

In this paper, a new explicit state variable was introduced which describes the AgSn intermetallic morphology inside of lead-free solder joints at different cooling rates. In the experiment, samples were prepared by melting standard Ag-content (4 % in wt%) and low Ag-content (0.3 % in wt%) solder alloys, and solidifying them at five different cooling rates between 0.8 and 3 K/s. Images were taken about the cross-section of solder joints by brightfield light-microscope to calculate the explicit state variables, which describe the morphology of precipitating AgSn intermetallic compounds. The captured images were processed then with an in-house developed automatic image processing algorithm. It was found that the area of AgSn intermetallic compounds followed exponential distribution, so a new state variable could be introduced, such as the amplitude of a certain exponential curve fitted to the area histogram of the AgSn IMCs. It was proven that our new variable described the different AgSn IMC morphologies obtained at different cooling rates better; it was more sensitive at both aforementioned solder alloys (4 and 0.3 % Ag content) than the widely applied parameters, like the mean-intercept length or the average area of particles. [ABSTRACT FROM AUTHOR]

Consolidated nano/sub-micron AZ31 Mg alloy is a new structural material that combines nano-scale grains with a size of up to 100 nm and sub-micron grains with a size of up to 300 nm. Inherently, this new material should have significantly improved strength, making it a potential candidate for special applications requiring increased specific strength. The present paper evaluates the properties of nano/sub-micron AZ31 Mg alloy in terms of mechanical properties and corrosion resistance. The obtained properties are explained and associated with the micro-structure of the alloy. In addition, the nano/sub-micron structural alloy was compared to conventional extruded alloy with the same composition in order to distinguish the main differences between the two alloys. [ABSTRACT FROM AUTHOR]

This paper presents the results of micro-tensile testing of the individual struts that were extracted from open cell aluminum foams in the as-fabricated (F), annealed (O) and T6-strengthened (T6) conditions. The results reveal that foam struts are generally stronger and more dutile than the corresponding solid alloys under the same heat treatment conditions. The distinguished strut properties are attributed to the unique grain structures of the struts typically consisting of one grain or having bamboo-like grain structure. The measured strut strengths are also incorporated into mechanics models to estimate foam strengths. A comparison of the predicted and measured foam strengths shows that direct measurement of strut properties is critical to make precise estimation of foam strengths. [ABSTRACT FROM AUTHOR]

Minor alloying addition or microalloying technology has already shown dramatic effects on glass formation and thermal stability of bulk metallic glasses (BMGs). This paper intends to provide a comprehensive review of recent developments of this technology in the field of BMGs. The beneficial effects of minor alloying additions on the glass formation and the thermal stability of BMGs will be summarized and analyzed. In addition, principles and guidelines for future application of this technology will also be proposed. [ABSTRACT FROM AUTHOR]

Mg-Zn-Zr wrought alloys have been widely developed for lightweight applications. Zr microalloying contributes to remarkable grain refinement during solidification and bimodal microstructure via forging. To obtain an optimum Zr content for a balance between cost and mechanical property, it is necessary to understand the influence of varied Zr addition levels on the microstructure and mechanical property of the final forged product. In the present study, two levels of Zr addition (nominally 0.40 wt.% and 0.60 wt.%) were added to a Mg-3 wt.% Zn alloy to investigate the effect of varied Zr contents on the microstructures under as-cast, as-forged and tensile-strained conditions, as well as the uniaxial tensile properties of the as-forged alloy. The as-forged microstructures comprise fine dynamic recrystallized (DRXed) grains and coarse deformed (unDRXed) domains, which become more refined with the Zr content increasing from ~ 0.43 wt.% to ~ 0.67 wt.%. The microstructural change caused by the increased Zr addition has minor impact on 0.2% proof stress but remarkably improves both uniform and post-uniform elongations, for which the underlying mechanisms have been discussed. [ABSTRACT FROM AUTHOR]

An effective alloying system for providing improved mechanical and technological properties of model cast Al–Cu alloys (Al-4.6%Cu-0.4%Mn-0.2%Ti), using magnetohydrodynamic (MHD) melt mixing, has been chosen in this research. It was shown that MHD treatment provides a non-dendritic (globular) ingot structure and can be applied to ensure thixotropy in the mass production of high-precision cast parts. Small additives of alloying elements that modify both grain structure (Mn, Zr) and reinforcing phases (Sn, In, Sc) were used. It is shown that the most effective alloying elements which improved the strength characteristics of the alloy are Sn and In. The introduction of 0.1–0.2% Sn or In followed by heat treatment led to a 50% increase in its yield strength, a 15% increase in the tensile strength. Sn and In modified the decomposition kinetics, providing a high density of precipitate and slow coalescence of nano-sized particles of the strengthening θ′-phase, which resulted in higher strength characteristics of the alloy. [ABSTRACT FROM AUTHOR]

Metal sulfide grain boundary precipitates of a ferrous model alloy with 13 wt.% chromium formed at 650°C under a gas atmosphere containing 0.5% SO2 and 99.5% Ar were investigated after ageing for 3 h, 6 h, and 12 h. The precipitates formed along grain boundaries were identified as Cr5S6 using energy-dispersive x-ray spectroscopy in transmission electron microscopy and electron backscatter diffraction analysis. Serial focused ion beam slicing was conducted followed by three-dimensional reconstruction to determine the number, size, and penetration depth of the precipitates evolved at the different time steps. There was a linear increase in the number of precipitates with time, while their average size increased only for the initial aging time but became constant after 6 h. Based on these results, a model for grain boundary sulfidation of ferritic alloys is discussed. [ABSTRACT FROM AUTHOR]

We present a process of semantic meta-model development for data management in an adaptable multiscale modeling framework. The main problems in ontology design are discussed, and a solution achieved as a result of the research is presented. The main concepts concerning the application and data management background for multiscale modeling were derived from the AM3 approach-object-oriented Agile multiscale modeling methodology. The ontological description of multiscale models enables validation of semantic correctness of data interchange between submodels. We also present a possibility of using the ontological model as a supervisor in conjunction with a multiscale model controller and a knowledge base system. Multiscale modeling formal ontology (MMFO), designed for describing multiscale models' data and structures, is presented. A need for applying meta-ontology in the MMFO development process is discussed. Examples of MMFO application in describing thermo-mechanical treatment of metal alloys are discussed. Present and future applications of MMFO are described. [ABSTRACT FROM AUTHOR]

Background: One of the main concerns for archaeo-metallurgists and archaeologists is to determine to what extent ancient craftsmen understood the effect of metal alloy composition and were able to control it in order to produce objects with the most suitable features. This problem can be investigated by combining compositional analyses of a high number of ancient artefacts with correlation analyses of the objects' age, production site, destination of usage etc. - and thus chemometric data treatment is carried out. In this study, multivariate analyses were performed on a matrix composed of elemental compositional data from 134 archaeological bronze objects, obtained by XRF analyses. Analysed objects have been dated back from the Eneolithic Period to the end of the Bronze Age including the early Iron Age and were excavated in Central Italy (mainly Abruzzo Region). Results: Chemometric analysis was performed attempting to visualise clouds of objects through PCA. In parallel and independently, object grouping was attempted using several different approaches, based on object characteristics (e.g. shape, weight, type of use - cutting or hitting and age) following indications given by archaeologists (or derived from the archaeological context). Furthermore, case-tailored data pretreatment (logratio-centred scaling) was used, but no homogeneous groups could be identified. Conclusions: By using chemometric data analysis, homogeneous groups of objects could not be detected, meaning that compositional data of alloys is not correlated with the considered objects' characteristics. This favours the conclusion that - without discussing the ascertained ability of ancient foundry-men - they had also already discovered the convenience of recycling broken objects thus producing a more or less similar bronze alloy each time, depending on materials' availability; necessary mechanical characteristics could then be obtained by post processing. [ABSTRACT FROM AUTHOR]

Nucleation is a critically important process as the rate of nucleation determines the number density of new phase particles and thus microstructures of a material during phase transformations. Predicting and controlling nucleation rates in solids is one of the grand challenges in materials science because the spatial scale involved in nucleation is at the atomic/nanoscale, the rate of nucleation process is extremely temperature sensitive, and the morphology of a critical nucleus can be highly nonspherical and complex. In this article, we briefly review the recent advances in modeling and predicting nucleation during solid-phase transformations based on the diffuse-interface or nonclassical description of critical nucleus profiles. The focus is on predicting the critical nucleus morphology and nucleation free energy barrier under the influence of anisotropic interfacial energy and elastic interactions. Incorporation of nucleation events in phase-field modeling of solid-to-solid phase transformations and microstructure evolution is also discussed. [ABSTRACT FROM AUTHOR]

Ti-Nb-based Gum Metals exhibit extraordinary superelasticity with ultralow elastic modulus, superior strength and ductility, and a peculiar dislocation-free deformation behavior, most of which challenge existing theories of crystal strength. Additionally, this kind of alloys actually displays even more anomalous mechanical properties, such as the non-linear superelastic behavior, accompanied by a pronounced tension-to-compression asymmetry, and large ductility with a low Poisson's ratio. Two main contradictory arguments exist concerning the deformation mechanisms of those alloys, i.e., formation of reversible nanodisturbance and reversible martensitic transformation. Herein we used the in-situ synchrotron high-energy X-ray scattering technique to reveal the novel intrinsic physical origin of all anomalous mechanical properties of the Ti-24Nb-4Zr-8Sn-0.10O alloy, a typical gum-like metal. Our experiments provide direct evidence on two different kinds of interesting, stress-induced, reversible nanoscale martensitic transitions, i.e., the austenitic regions with B2 structure transform to α" martensite and those with BCC structure transform to d martensite. [ABSTRACT FROM AUTHOR]

Impact toughness as a property has been acquiring increased importance in recent years, since data regarding this property can provide a means for assessing alloy ductility under high rates of deformation. The main objective of this study is to investigate the effects of Sr-modification, Fe-based intermetallic phases and aging conditions on the impact toughness of widely used 356 alloys. The total absorbed energy was measured using a computer-aided instrumented Instron Charpy impact testing machine. Increasing the level of iron additions decreases the impact energy values of 356 alloys to a noticeable degree (~35-57%). The addition of 0.1 wt% Mn to non-modified 356 alloys seems to have no observable effect on the impact energy, while increasing the Mn addition to 0.4 wt% produces a slight improvement in the impact energy values for non-modified and Sr-modified 356 alloys compared to that of those containing only iron under the same conditions. The application of solution heat treatment in combination with Sr-modification was found to significantly improve the impact energy of as-cast 356 alloys, particularly at low iron additions. Artificial aging of non-modified and Sr-modified 356 alloys at 180 °C diminishes the impact energy values with an increase in the aging time up to 8 h compared to those obtained under the solution heat-treated conditions. On the other hand, aging at 220 °C for 12 h increases the impact energy values of Sr-modified 356 alloy containing 0.12 wt% Fe and combined 0.2 wt% Fe-0.1 wt% Mn to about 20 and 18 J, respectively. The fracture behavior of non-modified 356 alloys containing 0.12 wt% Fe is mainly controlled by the acicular eutectic Si particles whereas β-iron platelets act as crack initiation sites and provide further path for final crack propagation in non-modified 356 alloys containing 0.9 wt% Fe. The β-iron platelets and π-iron phase particles contribute largely to crack initiation and propagation in the Sr-modified 356 alloys containing 0.9 wt% Fe. [ABSTRACT FROM AUTHOR]

Nanocrystalline ( nc) and microcrystalline ( mc) Fe10Cr alloys were prepared by high energy ball-milling followed by compaction and sintering, and then oxidized in air for 52 h at 400 °C. The oxidation resistance of nc Fe10Cr alloy as determined by measuring the weight gain after regular time intervals was compared with that of the mc alloy of same chemical composition (also prepared by the same fabrication route and oxidized under identical conditions). Oxidation resistance of nc Fe10Cr alloy was found to be in excess of an order of magnitude superior than that of mc Fe10Cr alloy. This article also presents results of secondary ion mass spectrometry (SIMS) of oxidized samples of nc and mc Fe–Cr alloys, evidencing the formation of a more protective oxide scale in the nc alloy. [ABSTRACT FROM AUTHOR]

Creep behavior of the Sn–2Bi–RE alloys containing 0.1, 0.25 and 0.5 wt% rare earth (RE) elements was studied by impression testing and compared to that of the Sn–2Bi alloy. The tests were carried out under constant punching stress in the range 70–190 MPa and at temperatures in the range 298–370 K. Results showed that for all loads and temperatures, Sn–2Bi–0.25RE had the lowest creep rate, and thus the highest creep resistance among all materials tested. This was attributed to the formation of Sn–Bi, Sn–RE, and Sn–Bi–RE intermetallic particles which act as both strengthening agent and grain refiner in the RE-containing Sn–2Bi alloy. RE contents higher than 0.25 wt%, resulted in a lower creep resistance due to the formation of the same intermetallics but with much higher Bi content. This consumes the Bi content of the matrix and reduces the corresponding solid solution hardening, resulting in a lower creep resistance of the material. The stress exponents in the range 8–10.5, 8.4–11.5, 8.8–12.3, 8.4–11.6 and average activation energies of 64.5, 65.1, 67.4 and 68.0 kJ mol−1 were obtained for Sn–2Bi, Sn–2Bi–0.1RE, Sn–2Bi–0.25RE, and Sn–2Bi–0.5RE, respectively. Although these activation energies are close to the activation energy of lattice self diffusion for β-Sn, the relatively high stress exponents of about 8–12 suggests that creep mechanisms associated with dislocation movement such as dislocation creep are prevailing. [ABSTRACT FROM AUTHOR]

The phase composition and magnetic state of Mn1 + xSb (0 ≤ x ≤ 1.0) alloys have been determined before and after high-pressure high-temperature processing ( p = 8 GPa, T = 2300 K). Exposure to high pressure and temperature is shown to extend the homogeneity range of hexagonal Mn1 + xSb alloys (sp. gr. P63/ mmc, no. 194) to x = 0.5. The alloys with x > 0.5 consist of two phases: hexagonal Mn1 + xSb and cubic Mn3Sb (sp. gr. Pm3 m, no. 221). The magnetic state of the alloys containing manganese in excess of the equiatomic composition can be understood in terms of a two sublattice model and ferrimagnetic ordering. [ABSTRACT FROM AUTHOR]

The progress achieved in the various epitaxial-growth procedures is significant enough today to allow the addressing of new questions related to the structures at the atomic scale of various defects in alloy materials. In this review we shall focus particularly on SiGe which is miscible in all proportions. The chemical disorder, resulting from mixing-entropy constraints, offers a large distribution of atomic environments around a given point defect. In the immediate neighborhood of the defect, which we shall restrict mainly to the first two or three atomic shells, none of the existing imaging techniques can provide any reliable information. On the other hand, electronic transport techniques, based on carrier capture and emission processes turns out to be very sensitive to the local atomic environment. The highly localized character of the wavefunction of the carriers trapped at the defect links the atomic environment of the defect to the carrier properties. In this work we shall illustrate these features for some simple but technologically important point defects in relaxed SiGe and makes an inspired guess at their atomic structures. [ABSTRACT FROM AUTHOR]

A comparison is made between the creep behavior of the Ti-35V-15Cr and Ti-35V-15Cr-0.2C alloys at 500 to 580 °C within the stress range of 200 to 300 MPa. The creep resistance of Ti-35V-15Cr-0.2C is considerably improved by the incorporation of Ti2C particulates into the Ti-35V-15Cr-0.2C matrix. [ABSTRACT FROM AUTHOR]

This study examined the characteristics of as-cast Ti-Cr(7-19%)-Cu(3-7%) (all percentages in this article are mass %) alloys to evaluate their suitability for dental applications; studies on the alloy structures and mechanical properties, grindability, and corrosion behavior were included in the investigation. The alloys were centrifugally cast and bench-cooled in investment molds. The x-ray diffractometry of the as-cast alloys bench-cooled in the molds indicated the following phases: α+β+ω in the 7% Cr and 7%Cr+3%Cu; β+ω in the 13%Cr; and β in the 13%Cr+3%Cu through the 19%Cr+3%Cu alloys. The strengths of the binary β Ti-Cr and ternary β Ti-Cr-Cu alloys with 13 and 19% Cr were approximately two times higher than those of CP Ti. The alloy ductility was dependent on the chemical composition and thus, the microstructure. The 7% Cr alloys were extremely brittle and hard due to the to phase, but the ductility was restored in the 13 and 19% Cr alloys. The hardness (HV) of the cast 13 and 19% Cr alloys was approximately 300-350 compared with a value of 200 for CP Ti. The grindability of the cast alloys was examined using a rotating SiC wheel at speeds (circumferential) of 500 and 1250 m/min. At the higher speed, the grindability of the 13 and 19% Cr alloys increased with the Cu content. The grindability of the 13% Cr alloy with 7% Cu was similar to that of CP Ti. Evaluation of the corrosion behavior in an artificial saliva revealed that the alloys are like many other titanium alloys within the normal intraoral oxidation potential. The wear resistance testing of these alloys also showed favorable results. [ABSTRACT FROM AUTHOR]

The strip producibility, good fabricability, and excellent mechanical properties of β alloys make them useful for a variety of fabricated sheet metal structures on aircraft. TIMETAL 15-3 is currently used for environmental control system ducting on the Boeing 777 and, more recently, has been used on the Airbus A380. For applications that require exposure to higher temperatures, such as the exhaust assemblies, TIMETAL 21S is now used on the Boeing 777, Airbus A340, and various other civil and military aircraft. [ABSTRACT FROM AUTHOR]

Abstract Sandwich structures with open cell truss cores are a relatively new class of multifunctional material systems that can be made using affordable deformation, assembly and joining processes. A variety of cellular core architectures have recently been made from wrought metal alloys using inexpensive textile and perforated sheet methods. Here, the design, fabrication and properties for these types of structures is reviewed. [ABSTRACT FROM AUTHOR]

In the case of metallic alloys, which present dendritic structure, the mechanical properties of foundry products depend on primary and secondary arm spacing. For the prediction of microporosities it is necessary to characterize precisely the dendritic structure formed during solidification, to calculate the permeability and also to estimate the radius of the gas bubble to determine the pressure due to gas/metal surface tension. Therefore, it is important in a computational simulation of the solidification processes to use reliable equations to correlate the calculated thermal parameters with primary and secondary dendrite arm spacing. This study presents a numerical and experimental analysis of some models to predict the primary and secondary arm spacing as a function of thermal parameters. Comparison between the numerical and experimental results for Al 4.5 wt% Cu alloy allowed the selection of adequate equations to predict the dendritic spacing during unidirectional solidification. [ABSTRACT FROM AUTHOR]

A new controller has been designed for vacuum arc remelting titanium alloys based on an accurate, low order, nonlinear, melting model. The controller adjusts melting current and electrode drive speed to match estimated gap and melt rate with operator supplied reference values. Estimates of gap and melt rate are obtained by optimally combining predictions from the model with measurements of voltage, current, and electrode position. Controller tests were carried out at Timet Corporation's Henderson Technical Laboratory in Henderson, Nevada. Previous test results were used to correlate measured gap to voltage and current. A controller test melt was performed wherein a 0.279 m diameter Ti-6Al-4V electrode was melted into 0.356 m diameter ingot. Commanded melt rate was varied from 20 to 90 g/s and commanded gap was held at 1.5 cm. Because no measure of electrode weight was available on the test furnace, electrode position data were analyzed and the results used to determine the actual melt rate. A gap-voltage-current factor space model was used to check estimated gap. The controller performed well, and both melt rate and electrode gap control were successfully demonstrated. [ABSTRACT FROM AUTHOR]

The electrochemical behaviour of copper-nickel alloys with different Ni content (5-65%) in sulphate solutions of pH 12 was investigated. The effects of temperature, immersion time, and concentration of sulphate ions were also studied. Different electrochemical methods such as open-circuit potential measurements, polarization techniques and electrochemical impedance spectroscopy (EIS) were used. Potentiodynamic measurements reveal that the increase in nickel content increases the corrosion rate of the alloy in sulphate solution linearly. Nevertheless, an increase in the nickel content along with increase in immersion time improves the stability of the Cu-Ni alloys due to the formation of a stable passive film. An equivalent circuit model for the electrode/electrolyte interface under different conditions was proposed. The experimental impedance data were fitted to theoretical data according to the proposed model. The relevance of the model to the corrosion/passivation phenomena occurring at the electrode/ solution interface was discussed. [ABSTRACT FROM AUTHOR]

The joint properties of dissimilar formed Al alloys, cast Al alloy and wrought Al alloy, were examined with various welding conditions. Friction stir welding method could be applied to join dissimilar formed Al alloys which had different mechanical properties without weld zone defects under wide range of welding condition. The weld zone of dissimilar formed Al alloy exhibited the complex structure of the two materials and mainly composed of the retreating side material. The mechanical properties also depended on the dominant microstructure of the weld zone with welding conditions. The different mechanical properties of the weld zone with welding conditions were related to the behavior of the precipitates of wrought Al alloy and Si particles of cast Al alloy. The higher mechanical properties of the weld zone were acquired when a relatively harder material, wrought Al alloy, was fixed at the retreating side. [ABSTRACT FROM AUTHOR]

The high-temperature corrosion behavior of cold-rolled and annealed 304 stainless steel (304SS) and Fe-29Mn-8Al-2.5Si-2Cr-0.74C alloy coated with 0.002 g cm-2 NaCl initially were studied at 900°C in air. The corrosion kinetics of the two alloys follow the parabolic rate law. The initial NaCl coating accelerates oxidation of these alloys by oxychlorination and chlorination/oxidation cyclic reactions, and catalytic actions of chloride or chlorine are thought to be the principal causes. A bulky, layered scale as well as some intergranular attack is noted on the annealed 304SS, and intergranular attack distributes over the alloy substrate of the cold-rolled 304SS during a 144 h exposure. With the formation of a compact Al2O3 scale to decrease further chlorine attack, the corrosion resistance of Fe-Mn-Al alloy is superior to that of 304SS in this study. [ABSTRACT FROM AUTHOR]

A bath for the electrodeposition of white gold alloys of interest for the electroforming of hollow jewelry is proposed and investigated. The system was an acidic Au(III)–Sn(IV) bath for the electrodeposition of Au–Sn alloys. The electrochemical investigations were based on cyclic voltammetry, linear-sweep voltammetry, galvanostatic electrodeposition experiments and in situ Raman spectroscopy. The electrode kinetics of alloy formation were elucidated by stripping voltammetry. The effects of cathodically adsorbed CN- were studied by in situ Raman spectroscopy. Electrodeposited foils were studied from the crystallographic, compositional and morphological points of view. Codeposition of Au and Sn gives rise to a single phase of approximately equiatomic composition over a current density interval of 10 to 40 mA cm-2. This orthorhombic phase is structurally the same as the ζ′ phase of the equilibrium Au–Sn system, but its stoichiometry and lattice parameters are different. The equilibrium two-phase δ, ζ′ structure can be obtained by heat-treatment. [ABSTRACT FROM AUTHOR]

Sn-Bi-Ag-(ln) solder alloys have been extensively studied in the study. The experimental results reveals that the liquidus temperatures of Sn-(1-5) Bi-(2-3.5)Ag-(0-10)ln solders are between 201.7 and 225.3°C, which were higher than that of the most popular eutectic Pb-Sn solder (183°C). Additions of (5-10) wt% In into Sn-Bi-Ag solders can effectively decrease the melting point of the solder alloy. However, the gap between Ts and TL temperatures increases with the additions of Bi and In into Sn-B i-Ag-(ln) solders. Although there is no flux applied during soldering, most Sn-Bi-Ag-(ln) solder alloys can well bond the Au/Ni metallized copper substrate. 945n-3Bi-3Ag solder demonstrates the lowest wetting angle of 45° among all test samples. Thermal expansion coefficients of both 945n-3Bi-3Ag and 90Sn-2Bi-3Ag-5In solders are slightly less than that of 63Sn-37Pb. Both 90Sn-2Bi-3Ag-5In/substrate and 945n-3Bi-3Ag/substrate interfaces demonstrate similar reaction kinetics in the experiment. The stability of the interface is greatly impaired during 90°C aging. Some locations of the electroless Ni layer break down, and new phases are formed nearby the interface during aging treatment. Initially, the growth of Ni-rich (Ni,Cu)3Sn4 phase dominates the interfacial reaction. However, the growth of Cu-rich (Cu,Ni)6Sn5 phase will dominate the reaction layer for specimens aged at 90°C for long time periods. [ABSTRACT FROM AUTHOR]

By consecutive deposition at two different current densities from a single sulfate-chloride bath, compositionally modulated multilayered (CMM) coatings of Zn-Ni alloys, with different number, thickness and sequence of the sublayers were obtained. The corrosion resistance of the coatings was studied by potentiodynamic dissolution and by corrosion potential measurement. in the current-potential (stripping) curves two well-defined peaks were observed. With increase in the number of sublayers, regardless of their individual thickness, the correlation between the amount of Zn, dissolved at more negative potentials and the whole amount of the metal in the CMM coatings, decreases. The corrosion potentials of CMM coatings are most positive (-0.940 V vs SSE) when they end with a Zn-Ni 18 % oversublayer. As a result of the alternation of Zn-Ni alloy sublayers with different Ni content the obtained CMM coatings have increased corrosion resistance in comparison with the monolayer coatings of the composing alloys. [ABSTRACT FROM AUTHOR]

The steady-state current-voltage characteristics of TlInX2-TlSmX2 alloys were measured as a function of sample composition and thickness. The results demonstrate that the alloys studied exhibit threshold switching. The threshold voltage decreases with increasing mean atomic weight and can be stabilized by heat treatment. The most stable current-voltage characteristics are obtained for thin-film samples. [ABSTRACT FROM AUTHOR]

The Al-Cu-Mg-Si alloying system is a base for a diverse group of commercial alloys which acquire their properties after quenching and aging. Therefore, the knowledge of the phase composition of hardening precipitates and the conditions under which they are formed is very important. Vast reference data were analyzed along with experimental results and calculations of phase equilibria. Different alloys were compared based on the composition of the supersaturated solid solution. It is shown that the phase composition of aging products in alloys with Mg : Si>1 agrees well with the equilibrium phase composition at a temperature of annealing. However, the sequence of precipitation in the alloys with Mg : Si < 1 is more complicated. The hardening in these alloys occurs with precipitation of the β" and θ' phases and their precursors. The former phase may contain copper and later transforms either to β' and β (Mg2Si) or to Q phase depending on the amount of copper and annealing temperature. [ABSTRACT FROM AUTHOR]

In this work the results of the experimental study of surface tension (ST) of alkali metals and their Na-K-Cs ternary system over the whole composition range and for temperatures from the melting point to 680 K are presented. Careful thermal treatment for several hours at 700 K under 10- 7 Pa vacuum condition and a new way of loading the measuring cell have been used to exclude possible contamination of the liquid metals and the measuring cell. To measure ST the sessile-drop method, which yields an experimental error of 1% with 95% probability, was used. Contents of impurities were not larger than 0.005%.Surface tensions of 110 Na-Cs-K alloys have been measured over the whole composition triangles for the first time. Polytherms of ST for pure metals and ternary alloys are well described by linear equations. The isotherms of ST for each Na/Cs +Ksection have been constructed. It was found thatKis a surface-active addition in ternary alloys when XNa:XCs>14:1, while it becomes a surface-inactive component if XNa:XCs<14:1. All ternary alloys along the XNa:XCs = 14:1 section have the same ST, independent fromKcontent. Lines of equal values of ST have been plotted for the whole composition triangles as well. [ABSTRACT FROM AUTHOR]