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Aluminium alloys are somehow the workhorse among light metals: spreading from castable, work hardenable to age-hardenable alloys, a wide panel of alternatives is available for the users. Nevertheless, continuous improvement of these alloys is ongoing, looking for higher strength, wider service temperature ranges, and suitability for new manufacturing processes.Likewise, a better knowledge of microstructure and ‘finer’ effects have to be encompassed.A proper multiscale approach and competent preparation are advisable for the best interpretation of the performances of new or ‘revised’ alloys.In this work a case study is presented in which multiscale approach has been used in order to explain the behavior of relatively widely used alloys, and also the problems and solution adopted in order to obtain the best results from microstructural analyses.Wrought age hardenable alloys were analyzed to have a better comprehension of ‘high temperature’ evolution of microstructure. The overall appearance of the microstructure was first identified by optical microscopy. Scanning Electron Microscopy (SEM) was involved to analyze grain size, type and size of secondary phases and texture. The results supported modeling studies related to the effect of grain size and texture. Finally, High Resolution Transmission Electron Microscopy (HR-TEM) investigations helped to understand the modification in the decay of mechanical properties upon extended overaging.

This work deals with the microstructural evolution of creep resistant martensitic/ferritic 11% Cr-steel during thermomechanical treatment from an experimental as well as modeling point of view. The creep resistance of this material group is highly dependent on the precipitate status. The initial precipitate status is controlled by the chemical composition of the alloy and the heat treatment after casting or hot rolling. It is therefore of utmost interest to understand and model the precipitate kinetics during this process. Once the microstructural evolution has been modeled successfully, only minimum effort is required to computationally test variants in the composition or heat treatment in order to optimize the process. In this work, the material was hot rolled, austenitized and subsequently annealed. All heat treatments have been performed during dilatometry tests. In order to investigate the microstructural evolution during the process, specimens were extracted at definite stages of the treatment. The specimens were then investigated applying various microscopical techniques in order to quantify the microstructural features (grain size, martensite lath width and precipitate data). The experimental data were then compared to thermodynamic simulations (MatCalc). General data such as nucleation sites for precipitates were taken from literature, grain size and martensite lath widths from the experimental data. Simulations include equilibrium calculations and precipitate kinetic simulations. In general, the simulations showed good agreement with the experimental findings, with minor room for improvements. The work thus lays a solid ground for future improvements of the heat treatment process.

The mechanical properties of Al alloys are strongly affected by their microstructure: the size and shape of precipitates, their homogeneous distribution and their coherency with the matrix are of primary importance for an effective strengthening of the alloys at room and elevated temperatures. Physically-based models are powerful tools to predict the influence of the mentioned parameters on the mechanical properties of the alloy after age hardening, and also to predict the effect of high temperature service conditions on microstructure evolution. Scope of this work is to model the dimensional kinetic evolution of plate shaped precipitates of an Al-based alloy during aging and after different overaging times at elevated temperature, and use these results to estimate the alloy yield strength. The alloy strengthening response is due to three terms, linearly summed: the intrinsic strength of Aluminum, the contribution from solute in solid solution and the contribution arising from precipitates. The consistency of the model is verified with experimental data obtained from a 2014 Al alloy.

The current status of international microgrid research, development, and demonstration (RD&D) was on display and open for review and debate in Tianjin, China, 13?14 ?November 2014 at the Tianjin 2014 Symposium on Microgrids. Sponsored by the U.S. Department of Energy Office of Electricity Delivery and Energy Reliability (U.S. DOE-OE) and the Energy Foundation, organized by Tianjin University, Hefei University of Technology, and supported by other generous sponsors, the tenth in the influential series of microgrid symposiums was held at the Geneva Grand Hotel. Broad international participation was achieved, with 106 attendees from 18 countries (Figure 1). There were 26 technical presentations by speakers from around the globe as well as a panel session on standards development and technical tours to the Tianjin ?Eco-City sustainable city development, Tianjin University?s Microgrid Laboratory, and the Yanqing dc microgrid near Beijing. The formal welcome was offered by Zhipeng Liang, deputy director of the ?Renewable Energy Department, Chinese National Energy Administration.

The paper provides a new insight into the modification of eutectic Si in Al-Si based alloys. To date, impurity-induced twinning mechanism and twin plane re-entrant edge mechanism are the well-accepted theories. However, neither IIT nor TPRE can be used to interpret all modification observations. Therefore, a re-consideration of modification mechanisms is still required. In this contribution, recent advances on the understanding the modification of eutectic Si are reviewed. Two different cases are highlighted. In the case of Sr, Na and Eu addition, eutectic Si was modified from a faceted to a fibrous morphology, which involves the formation of multiple Si twinning. In the case of Yb and Ca addition, eutectic Si was refined to a smaller size, but still maintained a plate-like morphology. The possible modification mechanism was thus discussed in terms of (i) adsorption of atoms at twin re-entrant edge, and (ii) segregation across {111}Si growth planes. Furthermore, solute entrainment of modifying elements (M) was introduced to interpret the formation of Al2Si2M phase or M-rich clusters within Si crystals.

The combination of porous silicon (PS) with iron oxide nanoparticles results in a nanocomposite system offering a magnetic behavior which is influenced by the properties of the nanosized particles but also by the morphology of the matrix. Mesoporous silicon, fabricated by anodization of a highly n-doped silicon wafer offers oriented pores with average diameters of 50 nm and 90 nm, respectively. Fe3O4 nanoparticles of different size (3.8, 5 and 8 nm) have been used to deposit into the pores of these matrices. The resulting composite exhibits a desired transition temperature between superparamagnetic (SPM) behaviour and blocked state which can be modified by the size of the deposited particles, the distance between the particles and by the variation of the used porous silicon morphology, respectively. Beside scanning electron microscopy (SEM) a sophisticated method for TEM-investigations has been employed to figure out the various characteristics of the system.

Metal-nanostructures are electrochemically deposited within the pores of porous silicon to achieve a hybrid material with specific magnetic properties. For this purpose first the porous silicon template is prepared by wet etching of an n+-type silicon wafer offering pore-diameters between 30 and 100 nm, depending on the anodization parameters. Secondly a ferromagnetic metal is electrodeposited into the pores, whereas the metal structures can be precipitated with various geometries and different spatial distributions depending on an accurate control of the deposition conditions. This method allows to deposit structures as spheres, ellipsoids or wires with a size up to a few micrometers in length whereas the diameter corresponds to the pore-diameter. In the case of Ni the deposition of small particles (2 - 5 nm) succeeded. These nanoparticles are covering the pore-walls and form depending on the packing density tube-like arrangements.

Ni-nanostructures are electrochemically deposited within the pores of mesoporous silicon. The porous silicon template is fabricated with straight and separated pores. The geometry of the metal deposits can be tuned in a wide size range between 50 nm and a few micrometers and thus specimens with specific magnetic properties can be achieved. Furthermore small Ni-particles between 3 and 6 nm in size can be precipitated on the pore walls with various distances. In the case of a closely packed distribution the particle arrangement results in metal tubes which cover the pore walls. The superparamagnetic Ni-particles forming such a tube are magnetically interacting which leads to a ferromagnetic behavior of the system.

The infiltration of iron oxide nanoparticles into mesoporous silicon is performed to investigate the influence of different arrangements of the particles on the magnetic behaviour of the achieved nanocomposite consisting of a semiconductor and a magnetic material. The porous silicon is fabricated from a highly doped n-type silicon wafer by anodization. The Fe3O4 particles fabricated by high temperature decomposition offer a size of 5 and 8 nm, respectively. In the present work the influence of the porous silicon matrix on the magnetic behaviour of such hybrid materials is figured out. In general iron oxide particles of a few nanometer in size are superparamagnetic but due to dipolar coupling between them the blocking temperature can be shifted, which is demonstrated by modification of the particle size and the distance between the particles.

Porous silicon matrices fabricated by wet etching are used as template for the deposition of metal nanostructures. The anodization of the silicon wafer is performed on one or on both sides in employing a double-tank electrolytic cell. The resulting porous layers are subsequently filled with a ferromagnetic metal by electrodeposition. In case of double-sided samples an alternating pulsed current is applied. These two processes are extended to ultrathin samples with an entire thickness of about 60 um. The morphology of the porous structure exhibits average pore-diameters of 60 nm, a mean pore-spacing of 45 nm and a pore-length of 40 um. Ferromagnetic metals are electrochemically deposited as nanostructures with a specific distribution within the pores.

Electrochemical dealloying has become a standard technique to produce nanoporous network structures of various noble metals, exploiting the selective dissolution of one component from an alloy. While achieving nanoporosity during dealloying has been intensively studied for the prime example of nanoporous Au from a AgAu alloy, dealloying from other noble-metal alloys has been rarely investigated in the scientific literature. Here, we study the evolution of nanoporosity in the electrochemical dealloying process for both CoPd and AgAu alloys using a combination of in situgrazing-incidence small-angle X-ray scattering (GISAXS), kinetic Monte Carlo (KMC) simulations, and scanning transmission electron microscopy (STEM). When comparing dealloying kinetics, we find a more rapid progression of the dealloying front for CoPd and also a considerably slower coarsening of the nanoporous structure for Pd in relation to Au. We argue that our findings are natural consequences of the effectively higher dealloying potential and the higher interatomic binding energy for the CoPd alloy. Our results corroborate the understanding of electrochemical dealloying on the basis of two rate equations for dissolution and surface diffusion and suggest the general applicability of this dealloying mechanism to binary alloys. The present study contributes to the future tailoring of structural size in nanoporous metals for improved chemical surface activity.

In 9–12% Cr steels, nitrides (MX, M2X) and modified Z-phase ((Cr, V, Nb, Fe)N)) are of special interest because of their different contribution to the creep strength of the material. The changes in the chemical composition of complex nitrides and their crystallography were investigated using transmission electron microscopy. A method based on multiple linear least squares fit procedures was applied to extract the complete element content of the nitrides from the electron energy loss spectra. These results, augmented by X-ray spectroscopic data, were compared with the outcomes of the thermodynamic model implemented in the software package MatCalc. The elemental concentrations of precipitates under study i. e. the M2X, MX and modified Z-phase are in good agreement with simulations.

In the high temperature deformation window of the nickel base Alloy 80A the lower temperature region during open die forging was examined with regard to the materials formability. For that purpose, hot compression samples were investigated by means of EBSD and TEM in order to look at recrystallization, precipitations and ductile damage as well as their reciprocal effects. Further a microstructure model was used, which calculates the materials strengthening, softening and the particle kinetics. A micro mechanical damage model of the effective stresses was coupled with the grain structure development in order to describe a retarded damage rate due to the ongoing recrystallization.

Rate coefficients for the gas-phase reaction of hydroxyl (OH) radicals with dimethyl sulfide (CH3SCH3, DMS) have been determined using a relative rate technique. The experiments were performed under different conditions of temperature (250–299 K) and O2partial pressure (∼0 Torr O2−380 Torr O2), at a total pressure of 760 Torr bath gas (N2+ O2), in a 336 l reaction chamber, using long path in situFourier transform (FTIR) absorption spectroscopy to monitor the disappearance rates of DMS and the reference compounds (ethene, propene and 2-methylpropene). OH was produced by the photolysis of H2O2. The following Arrhenius expressions adequately describe the rate coefficients as a function of temperature (units are cm3molecule−1s−1): k= (1.56 ± 0.20) × 10−12exp[(369 ± 27)/T], for ∼0 Torr O2; (1.31 ± 0.08) × 10−14exp[(1910 ± 69)/T], for 155 Torr O2; (5.18 ± 0.71) × 10−14exp[(1587 ± 24)/T], for 380 Torr O2. The results are compared with previous investigations.

ABSTRACTCadmium sorption from aqueous solutions on sulfonic (C-150) and iminodiacetic (S-930) Purolite macroporous resins was investigated. The influence of operating variables such as initial pH, Cd(H) concentration, time and temperature on the equilibrium parameters was measured. The ion preference and sorption ability of resins, i.e. binding constant (b) and saturation capacity {xm), derived from sorption isotherm, depend on the functional group structure. The Cd(II) uptake is only particle diffusion controlled. The kinetic parameters, i.e. t1/2values for 50 % attainment of equilibrium sorption, rate constant (K¯ ) and diffusion coefficient (D¯) are higher on the sulfonic resin. The “moving boundary” particle diffusion model fits the entire ion sorption process on chelating resin, but only the initial sorption on the sulfonic resin, confirming the difference in chemistry between chelation and ion exchange.

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Metal-nanostructures are electrochemically deposited within the pores of porous silicon to achieve a hybrid material with specific magnetic properties. For this purpose first the porous silicon template is prepared by wet etching of an n+-type silicon wafer offering pore-diameters between 30 and 100 nm, depending on the anodization parameters. Secondly a ferromagnetic metal is electrodeposited into the pores, whereas the metal structures can be precipitated with various geometries and different spatial distributions depending on an accurate control of the deposition conditions. This method allows to deposit structures as spheres, ellipsoids or wires with a size up to a few micrometers in length whereas the diameter corresponds to the pore-diameter. In the case of Ni the deposition of small particles (2 - 5 nm) succeeded. These nanoparticles are covering the pore-walls and form depending on the packing density tube-like arrangements.

The combination of porous silicon (PS) with iron oxide nanoparticles results in a nanocomposite system offering a magnetic behavior which is influenced by the properties of the nanosized particles but also by the morphology of the matrix. Mesoporous silicon, fabricated by anodization of a highly n-doped silicon wafer offers oriented pores with average diameters of 50 nm and 90 nm, respectively. Fe3O4 nanoparticles of different size (3.8, 5 and 8 nm) have been used to deposit into the pores of these matrices. The resulting composite exhibits a desired transition temperature between superparamagnetic (SPM) behaviour and blocked state which can be modified by the size of the deposited particles, the distance between the particles and by the variation of the used porous silicon morphology, respectively. Beside scanning electron microscopy (SEM) a sophisticated method for TEM-investigations has been employed to figure out the various characteristics of the system.

The infiltration of iron oxide nanoparticles into mesoporous silicon is performed to investigate the influence of different arrangements of the particles on the magnetic behaviour of the achieved nanocomposite consisting of a semiconductor and a magnetic material. The porous silicon is fabricated from a highly doped n-type silicon wafer by anodization. The Fe3O4 particles fabricated by high temperature decomposition offer a size of 5 and 8 nm, respectively. In the present work the influence of the porous silicon matrix on the magnetic behaviour of such hybrid materials is figured out. In general iron oxide particles of a few nanometer in size are superparamagnetic but due to dipolar coupling between them the blocking temperature can be shifted, which is demonstrated by modification of the particle size and the distance between the particles.

Ni-nanostructures are electrochemically deposited within the pores of mesoporous silicon. The porous silicon template is fabricated with straight and separated pores. The geometry of the metal deposits can be tuned in a wide size range between 50 nm and a few micrometers and thus specimens with specific magnetic properties can be achieved. Furthermore small Ni-particles between 3 and 6 nm in size can be precipitated on the pore walls with various distances. In the case of a closely packed distribution the particle arrangement results in metal tubes which cover the pore walls. The superparamagnetic Ni-particles forming such a tube are magnetically interacting which leads to a ferromagnetic behavior of the system.

Porous silicon matrices fabricated by wet etching are used as template for the deposition of metal nanostructures. The anodization of the silicon wafer is performed on one or on both sides in employing a double-tank electrolytic cell. The resulting porous layers are subsequently filled with a ferromagnetic metal by electrodeposition. In case of double-sided samples an alternating pulsed current is applied. These two processes are extended to ultrathin samples with an entire thickness of about 60 µm. The morphology of the porous structure exhibits average pore-diameters of 60 nm, a mean pore-spacing of 45 nm and a pore-length of 40 µm. Ferromagnetic metals are electrochemically deposited as nanostructures with a specific distribution within the pores.