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• The present paper mainly investigates the damping behaviour of AA6061. • Grain refinement was studied with the help of electron back scattered diffraction. • Intermetallic behaviour was studied under the scanning electron microscope. • Damping behaviour is correlated with grain size and intermetallic behaviour. The effect of brass interlayer and water cooling on the damping behavior of friction stir welded AA6061 was investigated in the present work. The results revealed that weld samples showed better damping capacity than base metal attributed to the grain refinement. Moreover, the damping capacity of weld with the addition of interlayer is enhanced due to more grain refinement, formation of hard intermetallics, and high inherent damping capacity of brass. The reduced intermetallics and formation of smooth interface obtained for water-cooled weld attributed to the faster cooling rate improved the mobility of grain boundaries which enhanced the damping capacity than natural cooling. The water-cooled weld with interlayer showed better damping at high temperatures than other weld joints due to the increased grain boundary area. [ABSTRACT FROM AUTHOR]

• The addition of boron can effectively refine the grain size and improve the tensile strength of the alloy at room temperature. • With the increase of boron content, the complex permittivity and permeability of the material are significantly improved, and the microwave absorption performance at low frequency is improved. • When the boron content is 0.06 at%, the minimum reflection loss peak reaches −10.7 dB at 1.9 GHz. Flaky FeSiAlB alloy powders were prepared by melting, quenching and milling. The effects of boron on the microstructure of FeSiAl alloy powders, the element distribution on the grain boundary of parent alloy, and the room temperature tensile properties of as-quenched sheet were studied by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectrometer (EDS) and tensile testing machine, respectively. With the addition of boron, the grain size of the master alloy was refined, and the tensile strength of the quenched sheet at room temperature was significantly improved. And obvious boron-rich regions were observed at grain boundaries. Soft magnetic properties were measured by vibrating sample magnetometer (VSM). Based on the electromagnetic parameters measured by vector network analyzer (VNA), the microwave absorption properties of flaky powder were calculated. The particles with high flake have high permittivity and permeability. Reflection loss (RL) shows that when B content amount was 0.06 at%, the absorption performance of the original FeSiAl absorbing material is improved in L and S bands, and the absorption peak moves from high frequency to low frequency. Excessive B element will lead to impedance mismatch, and the absorption performance in L and S bands will gradually decrease. For FeSiAlB flaky powder with 0.06 at % B content, the RL is −10.7 dB at 1.9 GHz and the matching thickness is 3 mm. [ABSTRACT FROM AUTHOR]

Zn alloy has attracted much attention in recent years as a new biomedical degradable material. However, how to simultaneously achieve its high strength and high ductility is a bottleneck problem to be solved. In this study, the Zn-2.0Cu-0.1Ti alloy with ununiform heterostructure, consisting of the barren areas without CuZn 5 phase and the regions enriched with CuZn 5 phase, was designed and successfully fabricated through controlled stir casting and hot extrusion. Uniaxial tensile test and Vickers hardness test were applied to reveal the mechanical properties of the Zn-2.0Cu-0.1Ti alloy, while electrochemical test and immersion test were used to characterize its degradation properties. The novel heterostructure was systematically examined by optical microscope (OM), scanning electron microscope (SEM), and transmission electron microscope (TEM). It was found that the yield strength and ultimate tensile strength of the present Zn-2.0Cu-0.1Ti alloy reach 241.2 ± 4.7 MPa and 265.8 ± 1.3 MPa, showing 294.4% and 230.3% improvement over those of pure Zn. Even more surprising is that the improved strength can be achieved without sacrificing ductility. The substantially increased strength can be mainly attributed to the strengthening mechanisms of grain refinement and Orowan looping, and the maintenance of good ductility thanks to the excellent dislocation storage ability of the present heterostructure. At the same time, the corrosion rate of the alloy in simulated body fluids also reaches the industry standard for orthopedic implants. This study not only sheds light on the design and fabrication of Zn-based material for surgical implantation application but also provides a feasible route to improve the mechanical properties of other precipitates reinforced alloys. • Heterostructure with ununiform dispersion of CuZn 5 was constructed in Zn-2.0Cu-0.1Ti alloy. • The significant strength improvement over pure Zn was achieved without sacrificing ductility. • The involved strengthening and toughening mechanisms were deeply discussed. • The slightly increased corrosion rate was explained in terms of the heterostructure. [ABSTRACT FROM AUTHOR]

Corrosion processes of SiC-CaAl 12 O 19 (CA 6) composite refractory were carried out by both static crucible test and rotary drum test at 1500 °C and 1600 °C under a reducing atmosphere, respectively. The corrosion mechanism of the SiC-CA 6 refractory was analyzed by means of X-ray diffraction(XRD) and scanning electron microscope(SEM). The results show that the corrosion temperature and condition had significant influence on the slag resistance of the SiC-CA 6 refractory. But no matter which corrosion methods and which temperatures under the condition of this experiment, the SiC-CA 6 refractory exhibited good penetration resistance even though a little corrosion appeared at a higher temperature. During the corrosion process, most of Fe containing oxide in slag could be reduced by CO in atmosphere and SiC in samples to form Fe-Si metal alloys, which precipitated at the interface between the slag and composites. The penetrated slag could react with the SiO 2 produced by SiC oxidation and the CA 6 matrix to form CaAl 2 Si 2 O 8 and corundum, filling the pore inside the samples and causing the densification of the reaction layer. Because of the reaction between infiltrated slag and SiC-CA 6 refractory, the composition and properties of local slag changed and inhibited the further penetration. • High temperature corrosion processes of SiC-CaAl 12 O 19 (CA 6) composite refractory were carried out. • The corrosion mechanism of the SiC-CA 6 refractory was analyzed at evaluated experiment conditions. • The corrosion resistance of SiC-CA 6 refractory was compared with the traditional high chromia refractory. [ABSTRACT FROM AUTHOR]

Facets are flat faces of a single crystal, which are typically parallel to the low-energy lattice planes. The orientation of a facet can sometimes be determined by simple visual examination, as in the case of the gemstone industry. Facets on microscale particles often do not correspond to the expected results of equilibrium, and the smaller physical size presents a challenge in observation. Using a facet observed on spherical particles of 20 μm diameter in alloys of Al 60 Cu 25 Fe 15 composition as an example, a procedure to determine facet orientation based on the combined usage of Scanning Electron Microscope (SEM) and Electron Backscatter Diffraction (EBSD) has been proposed and tested. Out of three types of facets found, the crystalline orientation of one type is determined by two approaches: by examination of facet relative layout and by orientation analysis based on the usage of SEM-EBSD. The former is along the traditional line of visual examination and the latter represents an attempt to expand the application of EBSD in a different field. Both approaches proved that the surface of the facet is parallel to the {100} lattice plane of a cubic phase. The experimental details and the strength of SEM-EBSD in such application are discussed. • Spherical particles and facets were found. • Procedure to make electron beam normal to facet surface has been established in Scanning Electron Microscope operation. • A specimen holder was assembled, which enables specimen observation from different angles for different purposes. • The crystalline orientation of one type facet has been analyzed by two different approaches. • Electron Backscatter Diffraction was proven to be an effective technique in facet orientation analysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • Laser-powder bed fusion (L-PBF) fabrication of functionally graded nickel-titanium (NiTi)-AISI 316L material demonstrated. • Excellent bonding between NiTi and AISI 316L alloys controlled via complex bands of multi-material layers. • Phase and microstructural evolution controlled through the L-PBF settings. • Multi-material phase and microstructure formation/evolution mechanisms elucidated. This study evaluates the phase and microstructural evolution of additively manufactured (AM) Nickel Titanium (NiTi) alloy, across the interface with 316L stainless steel build plate, in order to understand the processing parameter (input power, layer thickness and scan speed), composition, and microstructure interrelationships necessary to achieve excellent multi-material bonding between NiTi and 316L. The effect of the process parameters utilised was characterised using the Scanning Electron Microscope (SEM), Electron Backscatter Diffraction (EBSD), X-ray diffraction (XRD), and Energy-dispersive X-ray spectroscopy (EDX). SEM/EBSD results demonstrated, for the first time, that the microstructure and phase close to the interface was complex and comprised martensite, austenite and Fe phases, sequentially arranged in a layered sandwich pattern across the build direction. This complexity was necessary for excellent bonding. The L-PBF process parameters influenced the diffusion behaviour and the concentration of elements found at the interface. The diffusion rate of Fe and Ti across the NiTi-316L interface was 3.05 × 10 - 6 m 2 / s and 3.27 × 10 - 8 m 2 / s , respectively, representing a 93.27-fold increase. The observed microstructural and phase evolution is related to the generated interface chemistry and the thermomechanical history related strain resulting from the L-PBF process. [ABSTRACT FROM AUTHOR]

Mg-xAl alloys (x = 3–12 wt%) were prepared by high pressure solidification. The microstructure of the alloys was studied using Scanning Electron Microscope (SEM) and Electron Backscatter Diffraction (EBSD), and the strengthening mechanism was analyzed in combination with the compressive properties of the experimental alloys. Furthermore, the grain boundary segregation of Al solute was investigated by experiments and first-principles calculations. For the Mg-xAl alloys solidified under atmospheric pressure, the microstructure will be a single solid solution when the Al content of the alloy is less than 5 wt%. However, for the Mg-xAl alloys solidified under 4 GPa pressure, the microstructure will always ba e single solid solution when the Al content of the alloy is less than 12 wt%. Moreover, the segregation of Al solute with a high concentration gradient can be observed at plenty of grain boundaries (area fraction is as high as 46%), because α-Mg dendrites are significantly refined under high pressure. In addition, many Al atoms are dissolved in the α-Mg matrix owing to high pressure. On this basis, it is found that grain boundary segregation of Al solute can decrease the grain boundary energy, and increase the bonding strength of grain boundaries. As a result, the Mg–Al alloys solidified under high pressure have superior compression properties. The compression strength of the Mg–9%Al alloy and the Mg–12%Al alloy solidified under 4 GPa is as high as 458 MPa and 490 MPa respectively, the alloys retain superior plasticity simultaneously. [ABSTRACT FROM AUTHOR]

The aim of this study is the investigation of the effect of ferroboron and ferrochromium with massive wire based hardfacing alloys. Mixture of Fe–Cr and Fe–B powders was added to massive wire during welding process. Hardface layers were obtained by three different powder mixture and three different powder/massive wire proportions. Hardfacing was applied to two AISI 1020 steel substrates by open arc welding. Hardness test, scanning electron microscope and X-ray diffraction analysis were made to the samples. Test results showed that increasing ferroboron content and increasing powder mixture amount enhanced the microhardness of the specimens. [ABSTRACT FROM AUTHOR]

The improvement of the surface qualities and surface hardening of precipitation hardened martensitic stainless steel 17-4PH was achieved by the plasma-transferred arc welding (PTAW) process deposited with Co-based alloy. The microstructure of the heat affected zone (HAZ) and base metal were characterized by optical microscope (OM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The results show that there are obvious microstructural differences between the base metal and HAZ. For example, base material is transformed from lath martensite to austenite due to the heateffect of the welding process. On the other hand, the precipitate in the matrix (bar-like shape Cr7C3 phase with a width of about one hundred nanometres and a length of hundreds of nanometres) grows to a rectangular appearance with a width of about two hundred nanometres and a length of about one micron. Stacking fault could also be observed in the Cr7C3 after PTAW. The above means that welding can obviously improve the surface qualities. [ABSTRACT FROM AUTHOR]

Accurate prediction of microstructural stability in an alloy depends not only on a sound knowledge of the thermodynamics of the system but also of the kinetics of the phase changes involved. Conventionally, precipitate growth mechanisms have been inferred from the variation with aging time of various single parameters such as the mean, mode or maximum of the precipitate size distribution, which has then been compared to theoretical models of growth of an individual precipitate. In the present study, the development, with aging time at 1003 K (730 °C), of the size and shape distributions of grain boundary precipitates in Co-20Fe has been examined to determine the rate-controlling processes, and the conclusions compared to those from conventional analysis. The growth of the precipitates was well described by the grain boundary-dependent collector plate mechanism of Brailsford and Aaron. As the precipitates grew, low-energy facets were formed, which could move only by the propagation of ledges, and thickening was inhibited. The precipitates' diffusion fields in the grain boundary overlapped and the size distributions of the longest aged specimens showed that local coarsening occurred under partial interface control. [ABSTRACT FROM AUTHOR]

The ceramic coatings with different thicknesses in the range of 150 μm to 490 μm, bonded on the same alloy substrates, were obtained by the air plasma spray method. The crack evolution and the fracture characteristics of the samples were observed synchronously under the three-point bending load using a scanning electron microscope. The results show different fracture modes for the thinner and the thicker coating samples; the multiple transverse cracks, vertical to the interface between the coatings and the substrates, in the coatings are the main fracture mode for the samples with coatings thinner than about 200 μm, while the interface crack is the main fracture mode for the samples with coatings thicker than about 300 μm. Different fracture modes were theoretically analyzed based on the nonlinear delamination model, and the calculated critical thickness is 255 μm, which agrees well with the experimental result. The finite element simulations for the corresponding coatings with a series of thicknesses were carried out by introducing the interface cohesive model, and the simulations show results similar to those of the experimental observations. The study indicates that the fracture modes depend on the thickness of the coatings, and the critical thickness depends on the intrinsic properties of coatings and the interfaces between the coatings and the substrates, such as the elastic modulus, the interface strength and the fracture energy. [ABSTRACT FROM AUTHOR]

• Synchrotron XRD confirmed the CALPHAD-predicted BCC phase in Cr 18 Fe 27 Mn 27 Ni 28 at 700 °C and a BCC phase in Cr 15 Fe 35 Mn 15 Ni 35 that was not predicted. • The alloys showed promising strength in tensile deformation, with yield strengths of 155 MPa and 151 MPa at room temperature for Cr 18 Fe 27 Mn 27 Ni 28 and Cr 15 Fe 35 Mn 15 Ni 35 , respectively, falling to 93 MPa, and to 100 MPa, respectively at 500 °C. • Heavy-ion irradiation yielded similar densities of dislocation loops in two-beam conditions, but differences in faulted loop populations were resolved with rel-rod contrast condition. • Cr 18 Fe 27 Mn 27 Ni 28 experienced void swelling in the target-dpa plateau region; Cr 15 Fe 35 Mn 15 Ni 35 resisted swelling in this region, but small voids nucleated beyond the displacement damage peak. • EDS indicates that vacancies migrate primarily via Mn-exchange, with the counter-diffusion of Ni more strongly affected than Fe or Cr. Two CrFeMnNi face-centered cubic complex concentrated solid-solution alloys (CSA) have been evaluated for phase stability, mechanical properties, and radiation damage effects from heavy ions. Cr 18 Fe 27 Mn 27 Ni 28 and Cr 15 Fe 35 Mn 15 Ni 35 were predicted by thermodynamic calculations to phase separate and maintain a single phase at 700 °C, respectively. Aging experiments at this temperature confirmed varying degrees of precipitation of a body-centered cubic phase in both Cr 18 Fe 27 Mn 27 Ni 28 and Cr 15 Fe 35 Mn 15 Ni 35. The alloys showed promising strength in tensile deformation at room temperature, with yield strengths of 155 MPa and 151 MPa for Cr 18 Fe 27 Mn 27 Ni 28 and Cr 15 Fe 35 Mn 15 Ni 35 , respectively. At 500 °C, the yield strength of Cr 18 Fe 27 Mn 27 Ni 28 fell to 93 MPa, and to 100 MPa in Cr 15 Fe 35 Mn 15 Ni 35. Unlike Cr 18 Fe 27 Mn 27 Ni 28 , Cr 15 Fe 35 Mn 15 Ni 35 gained some ductility at 500 °C compared to room temperature. The two CSAs were irradiated to 75 dpa at 500 °C in the plateau region of the displacement curve using 3.7 MeV Ni2+ ions, alongside model alloy 709 as a reference. Irradiation results produced similar densities and sizes of dislocations loops in the two CSAs compared to the reference. However, while large voids form in the plateau region of Cr 18 Fe 27 Mn 27 Ni 28 , small voids form just beyond the displacement peak of Cr 15 Fe 35 Mn 15 Ni 35. Atom probe tomography and energy dispersive X-ray spectroscopy-equipped scanning transmission electron microscopes were used to characterize the alloys for changes in chemical distribution. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, glass-forming ability (GFA) and thermal stability of melt-spun Al-Ni-Zr amorphous ribbons with different Zr content were investigated via X-ray diffraction, transmission electron microscope and differential scanning calorimetry. The electrochemical performance and hardness performance of the ribbons with different amorphous content were analyzed. It is shown that with the addition of Zr, the amorphous content and corrosion resistance first increases and then decreases. However, the hardness of the ribbons with a minor fraction of the amorphous content is the highest. To further study the influence of the Zr element on the GFA of Al-Ni-Zr alloys, ab initio molecular dynamics simulation was used to calculate the atomic structure, coordination number, and Voronoi polyhedron. The calculation results show that adding an appropriate amount of Zr affects the interaction between atoms, causing significant changes in the local structure and increasing the content of the icosahedron to improve the GFA. [ABSTRACT FROM AUTHOR]

• Effects of pre-strain on precipitation kinetics and strengthening mechanisms of γ'-strengthened HEAs were studied. • Pre-strain can accelerate precipitation kinetics but shows a non-monotonous feature with the increase of pre-strain. • The shortened defects existing time by recrystallization can weaken the acceleration effect at high pre-strain. • Strengthening mechanisms can be tuned by different pre-strain to realize targeted properties. Pre-strain is often used as a powerful pre-treatment to tailor the microstructures and mechanical properties of traditional alloys. However, in high-entropy alloys (HEAs), the effect of pre-strain degree on the precipitates is still unclear. In this paper, we investigated the effects of pre-strain degree on the precipitation of Ni 2 CoCrFeTi 0.18 Al 0.12 high-entropy alloys. The HEAs were cold-rolled with different thickness reduction of 30%, 50%, and 70% and annealed at 800 °C for 30 ~ 60 min, followed by high-resolution scanning electron microscope (SEM) analysis. Counter-intuitively, we discovered a non-monotonous effect of pre-strain on the precipitation behavior, that low pre-strain can accelerate the precipitation behavior while such accelerating effect is weakened under high pre-strain. This non-monotonous effect is attributed to the shortened defects existing time by recrystallization under high pre-strain. In addition, pre-strain can controllably tailor the precipitation strengthening, dislocation strengthening, and grain boundary strengthening of HEAs. These results not only uncover the mechanism of the non-monotonous pre-strain effect on the precipitates but also provides a pre-strain mediated scheme for tuning the precipitation-strengthened HEAs to targeted properties. [ABSTRACT FROM AUTHOR]

• The mechanical properties of microstructures depend on mesoscopic slip and fracture behavior. • There exist many long slip traces directly passing through the microtextured regions. • Blocked slip arouses a high stress concentration in microtextured region. • Slip transmission is related to alignment between two slip systems and their Schmidt factors. In this paper, the tensile behavior and deformation mechanism of two typical bimodal microstructures in Ti6242S alloy were investigated through the in-situ scanning electron microscope (SEM) test and electron backscatter diffraction (EBSD). The results showed that the two microstructures presented different mechanical properties due to the different microscopic slip and fracture behaviors. In the homogeneous microstructure (with homogeneous crystallographic orientation), most of the slip traces were restricted within the grains because the slip transmissions between neighboring grains were blocked. The slip deformation was relatively homogeneous. Therefore, the fracture mechanism was micro-void accumulation fracture. In the inhomogeneous microstructure (with many microtextured regions), there existed many long slip traces directly passing through the microtextured region (the region of α phase with similar crystallographic orientation), the slip behavior was closely related to the same basal slip. The blocked slip aroused a high stress concentration in microtextured region, which was easy to induce the formation of microcrack, and then the microcrack propagated along the slip band. This can be attributed to the fact that slip transmission behavior was closely related not only to the alignment between slip planes and slip directions in two neighboring slip systems , but also to their Schmidt factors (SFs). Thus, the fracture mechanism was the coexistence of micro-void accumulation facture and cleavage fracture. [ABSTRACT FROM AUTHOR]

The heterogeneous interface constituted by Cu and Al were diffusion-bonded with CuZn alloy fibre interlayer under different bonding parameters, which was compared with directly bonded Cu/Al interface to analyze the effects of the different intermetallic compounds (IMCs) occurred at the joining interface on the interface mechanical properties. The interface microstructure was analyzed by scanning electron microscope (SEM), the compositions profiles across the joining interface were measured by energy dispersive spectroscopy (EDS), the phase and grain in the bonding interface of a Cu/Al bond were carefully investigated via electron backscatter diffraction technique (EBSD), the results show that the interface phase of Cu/Al composites grows irregularly, which leads to the low uniformity of interface properties. By adding CuZn alloy fibre, the interface of Cu/Al shows cellular skeleton and promotes the uniform diffusion of interface. When the bonding time was 570 °C for 60 min, the average shear strength of Cu/CuZn/Al interface reached 60.7 MPa. Compared with Cu/Al interface, the standard deviation of shear strength decreased from 18.7 to 1.6, and the variance decreased from 3.7 to 1.1. • The diffusion of Cu and Al was promoted by the introduction of Zn. • CuZn alloy can improve the interface homogeneity of large area Cu/Al composites. • When CuZn alloy fibre was added, the fracture mode changed to mixed fracture. • The bonding time has a great effect on the uniformity of the interface. [ABSTRACT FROM AUTHOR]

Hot compression test was performed on Ti–6Al–2Zr–1Mo–1V alloy below the β-transus (T β) with the temperature range of 940–970 °C. Microstructural evolution, especially on the equiaxed primary α phase (α p), was characterized by scanning electron microscope (SEM), electron backscatter diffraction (EBSD) and transmission electron microscope (TEM). The results showed that the α p could transform into β during hot deformation at α+β two-phase region, i.e., deformation-induced transformation of α→β (DIT). DIT, as an additional softening mechanism, caused the unusual stress response on the flow curves, which was reflected by the fact of the steady stress (σ st)

• Spectral emissivity data of cupronickel alloy C7701 is first reported. • Emissivity of cupronickel alloy in different oxidation degrees are measured. • The quantified approach of emissivity during oxidation is established. In this paper, the emissivity of the cupronickel alloy C7701 during oxidation is measured at temperatures of 673, 773, 873 and 973 K over the spectral range from 2 to 22 μm. The measurement details including the experimental setup, the measuring method and the sample preparation are introduced. The effects of wavelength, temperature and heating time on emissivity are discussed. The cupronickel alloy samples in different oxidation at long wavelength degrees are prepared, and the corresponding emissivity data is measured. The surface micromorphology and composition of cupronickel alloy samples are analyzed by scanning electron microscope and X-ray diffraction to further study the influence of surface oxidation. Finally, a fitting model is established to quantitatively reveal the characteristics of emissivity with the heating time, and the emissivity relative errors of the fitting model are analyzed to be less than 4%. [ABSTRACT FROM AUTHOR]

To improve corrosion resistance and enhance biocompatibility of magnesium alloy, cathodic plasma electrolysis (CPE), a liquid phase plasma technique, was used to fabricate zirconia (ZrO2) coatings onto WE43 magnesium alloy substrate. Surface morphology and phase composition of the coatings on magnesium alloy substrates were investigated by scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. The potentiodynamic polarization test in simulated body fluid (SBF) indicated that corrosion resistance of magnesium alloy was significantly improved by this CPE treatment. The results of cytocompatibility including osteoblasts adhesion and viability suggested that surface modification of magnesium alloy with ZrO2 coating fo'rmed via CPE technique is beneficial for cell proliferation and differentiation. The approach presented here should be an attractive way for surface modification of magnesium-based implants to improve anticorrosion and bone osseointegration. [ABSTRACT FROM AUTHOR]

A shape memory alloy with medical applications was analyzed by corrosion point of view in Fusayama artificial solution after few thousand experimental cycles. Scanning electrons microscope, EDAX and potentiostat equipments were used to characterize the material surface and its behavior during and after an electric polarization. Pitting corrosion type was observed on the surface with accentuated aspects based on the fatigue process. Dimensional characterization of the pitting holes was realized using 2D and 3D imaging software possibilities and chemical modifications were analyzed in and near the corrosion marks. [ABSTRACT FROM AUTHOR]

Si-Ge composites have recently been explored as an anode material for lithium-ion batteries due to their stable cycle performance and excellent rate capability. Although previous reports show the benefits of Si-Ge composites on electrochemical performance, the specific mechanism and structural effects have been overlooked. Here, the structural effect of Si-Ge heterogeneous nanostructures on both mechanics and kinetics is systematically studied through theoretical analysis and detailed experimental results. Si-Ge and Ge-Si core-shell nanowires are employed for this study. The Si-Ge core-shell nanowires show a much improved electrochemical performance, especially cycle performance and rate capability, when compared to those of the Ge-Si core-shell nanowires electrode. On the basis of the detailed experimental results and associated theoretical analysis, its is demonstrated that the strain distribution and Li diffusivity and/or diffusion path are significantly affected by the Si-Ge heterostructure, which induce different mechanics and kinetics associated with lithium. [ABSTRACT FROM AUTHOR]

Tensile ductility of the Ti-based composites, which consist of a β-Ti phase surrounded by ultrafine structured intermetallics, is tunable through the control of intermetallics. The two Ti-based alloys studied exhibit similar compressive yield strength (about 1000MPa) and strain (about 35%-40%) but show a distinct difference in their tensile plasticity. The alloy Ti71.8Nb14.1Ni7.4Al6.7 fractures at the yield stress while the alloy Ti71.8Nb14.1Co7.4Al6.7 exhibits about 4.5% of tensile plastic deformation. To clarify the effect of microstructure on the deformation behavior of these alloys, tensile tests were carried out in the scanning electron microscope. It is shown that the distribution as well as the type of intermetallics affects the tensile ductility of the alloys. [ABSTRACT FROM AUTHOR]

This paper is aimed at investigating the corrosion behavior of Pure and Zinc-graphite particles with percentage of 1, 3, and 5%, respectively. The composites were fabricated by powder metallurgy method. Corrosion tests were performed according to ASTM standard. Corrosion rate was calculated and it is found that in all cases the corrosion rate was decreasing with the increase in exposure time. Meanwhile, the microstructure of composites was imaged and analyzed using optical microscope and scanning electronmicroscope. It is observed that the best corrosion resistance was zinc with 1%Graphite while Zinc with 3%and 5%Graphite composites did not enhance the corrosion resistance comparing to pure Zinc. [ABSTRACT FROM AUTHOR]

Epoxy resin attached to a fatigue fracture surface of Ti–Al–Nb alloy was removed using a removal method for hardly soluble organic material attached to metallic material, which has been developed by the author. In the removal method process, the epoxy resin attached to the fracture surface was treated with an organic solvent, `tetrahydrofuran', and cold concentrated sulfuric acid of nearly 100% purity. After the epoxy resin was removed from the fracture surface with the removal method, damage of the microscopic feature of the fracture surface was investigated using a scanning electron microscope (SEM). For the first time, the degree of the removal of the epoxy resin with the method was investigated by energy dispersive X-ray spectroscopy (EDS) in this research. After the removal, no damage of the fracture surface was found with SEM observation. In addition, C Kα derived from the epoxy resin was not detected with the EDS after removal. The result of the EDS analysis clarified that the epoxy resin was completely removed with the removal method. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Delayed and immediate crevice corrosions are investigated. [•] The crevice corrosion morphologies are studied by SEM. [•] The relocation of active dissolution region is observed. [•] The mechanisms of crevice corrosion are discussed in detail. [ABSTRACT FROM AUTHOR]

The grain boundary sliding and its accommodation mechanism during superplastic deformation have been identified by surface observations with focused ion beam in an Al–Zn–Mg–Cu alloy. The high-temperature in-situ tensile test is carried out in the scanning electron microscope under the region Ⅱ superplastic conditions. The experiment results indicate that the grain boundary sliding is the dominant superplastic deformation mechanism accommodated by diffusion creep and a little dislocation activity. The grain rotation also plays an essential role in superplastic deformation. There are no striated zones found in a vacuum environment, just cracks. A grain boundary sliding model is proposed based on the surface features. [ABSTRACT FROM AUTHOR]

Formation of profuse I 2 -type solute-enriched stacking faults (SESFs) in fine grains and transformation of SESFs to 18R-long period stacking ordered (LPSO) phase are attained in Mg-Er-Zn-Zr alloys. It is first confirmed by scanning Kelvin probe force microscopy (SKPFM) that SESFs with nanostructure act as weak anodes and the 18R-LPSO phase serves as cathode, which are verified by the theoretical calculated electronic work function and observation of scanning transmission electron microscope. Furthermore, the preferential corrosion of uniformly dispersed SESFs is demonstrated to be conducive to forming effective passivation film. It provides a new insight for developing high-strength and anti-corrosion Mg alloys. [Display omitted] • The PD of weak anode SFs is measured at the nanoscale by SKPFM for the first time. • The reliability of SKPFM results is verified by the theoretical calculated WF. • Preferential corrosion of SFs is demonstrated using STEM-EDS for the first time. • Preferential corrosion of solute-enriched SFs is conducive to formation of passivation film. • A new insight for designing high-strength and anti-corrosion Mg alloys is proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Graded NiCoW coating was synthesized by one step, galvanostatic, DC electrodeposition. • Graded NiCoW coatings possess composition and structure varying crossing thickness. • Induced co-deposition mechanism of graded NiCoW coatings has been elucidated. In this paper, a novel method for synthesis of functionally graded alloy coatings by using induced co-deposition has been proposed. The graded NiCoW alloy coatings were synthesized by one step, galvanostatic, direct current electrodeposition from a sulphate-citrate electrolyte. Scanning electron microscope, energy dispersive spectroscopy and X-ray diffractometer were applied to characterize the as-deposited coatings, which possess the composition and structure gradually varying crossing the coating thickness. During the electrodeposition, the competition between the formation of Ni complexes and Co complexes as well as the competition between induced deposition of W and direct deposition of Ni, are responsible for the formation of graded NiCoW coatings. This easy synthesis method by using induced electrodeposition should be a promising route for the preparation of functionally graded alloy materials. [ABSTRACT FROM AUTHOR]

The Mg-12Gd-2Er-0.4Zr (GE122K) is fabricated by double extrusion, and the effects of grain refinement and precipitate evolution on the mechanical performance of the extruded alloys are deeply analyzed. Scanning electron microscope results spectacle that some bulky precipitates in the single extruded alloy are fragmented to fine precipitates during double extrusion and distribute linearly along the extrusion direction (ED). The fine precipitates exhibit the strongest dispersion strengthening effect, whereas the bulky precipitates act as crack resources and decrease the elongation. After double extrusion, a refined grain structure with an average grain size of 2.7 µm is achieved, which is attributed to dynamic recrystallization (DRX). Moreover, double extrusion boosts the content of rare-earth elements into the matrix by dissolving the fine precipitates. During aging, extensive β′ precipitates form in the double extruded alloy than in the single extrude alloy. As a result, refined grains and strong precipitation strengthening make a significant contribution to a high yield strength (YS) of 422 ± 1.59 MPa with an elongation (EL) of 6.5 ± 0.89% in the double extruded+peak-aged alloy (ACX2). The possible strengthening mechanisms are discussed, and it is found that grain refinement and precipitate strengthening are the main contributors to the high strength of the GE122K alloy. Fabrication of Mg-12Gd-2Er-0.4Zr (wt%) alloy via double extrusion+aging with excellent mechanical performance. [Display omitted] • A facile and robust fabrication mechanism is adopted to attain an excellent balance of yield strength and elongation. • Grain refinement and precipitates have different effects on the strength of Mg-12Gd-2Er-0.4Zr alloy. • The β′ precipitate strengthening is the dominate strengthening mechanism during aging treatment of the extruded alloys. [ABSTRACT FROM AUTHOR]

In this study, a Mg-9Gd-4Y-2Zn-0.5Zr (wt.%) alloy was subjected, after solution treatment, to hot compression deformation at different temperatures (350 °C, 400 °C and 450 °C) and different strain rates (0.001 s−1, 0.01 s−1, 0.1 s−1 and 0.5 s−1) on a Gleeble-3800 thermal simulator. The evolution of the stress–strain curves under different conditions was compared. The changes in microstructure caused by the different deformation parameters and the change law of the long-period stacking-ordered (LPSO) phase during compression were observed and analyzed by optical microscope (OM) and scanning electron microscope (SEM). The results show that with the increase in the deformation temperature and the decrease in the strain rate, the degree of dynamic recrystallization (DRX) gradually increased, and the morphology of the phase also changed through, for example, twist fracture. The continuous dynamic recrystallization (CDRX) and discontinuous dynamic recrystallization (DDRX) mechanisms activated during the thermal deformation process can effectively refine the grains and weaken the texture in the alloy. [ABSTRACT FROM AUTHOR]

This study presents two analytical models for the laser powder bed fusion (LPBF) process. To begin, the single layer's dimensions were measured using principal operating conditions, including laser power, laser scanning speed, powder layer thickness, and hatch distance. The single-layer printing dimensions were transformed into multi-layer printing using the hatch distance. The thermal history of the printed layers was used as an input to the Johnson–Mehl–Avrami-Kolmogorov model to estimate the average dendrite grain size. LPBF experiments were conducted for a Cobalt–chromium (Co–Cr) alloy to validate the developed model. The average dendrite grain size was estimated using a scanning electron microscope (SEM) combined with "Image J" software. The Vickers hardness test was performed to correlate the average dendrite grain size and operating conditions. A 10–15% mean absolute deviation was presented between experiments and simulation results. In all samples, a Co-based γ-FCC structure was identified. An inverse correlation was established between the laser power and smaller average dendrite grain, while a direct relationship has been determined between laser scanning speed and average dendrite grain size. A similar trend was identified between hatch distance and average dendrite grain size. A direct link has been determined between the average dendrite grain size and hardness value. Furthermore, a direct relationship has connected the laser volume energy density and hardness value. This study will help experimentalists to design operating conditions based on the required grain size and corresponding mechanical characteristics. [ABSTRACT FROM AUTHOR]

The effect of initial Fe content on the iron removal efficiency, morphology evolution of the Fe-rich phase and the mechanical properties of the recycled Al-7Si-xFe-1.2xMn alloy during melt holding was studied using an optical microscope (OM), scanning electron microscope (SEM) and tensile testing. The results show that with the increase of the initial Fe content, the residual Fe concentration of the alloys gradually increased, and the corresponding removal efficiency of Fe gradually was increased to 77.67%. The type of Fe-rich phase in the alloys changes from α-Al15(FeMn)3Si2 to a mixture of α-Al15(FeMn)3Si2 and β-Al5FeSi, and its morphological evolution is as follows: coarse Chinese-script + polygon → dense Chinese-script + polygon → polygonal + dense Chinese-script + plate-like. Furthermore, the morphology of the Fe-rich phase in the slag changes from a polygonal shape to an irregular shape with a two-layer structure. The formation and increase of the inner layer with high Mn-content in the irregular-shape phase is the main reason for the increasing residual Fe content. The plasticity of the alloy increases obviously with the increase of the initial Fe content, but the formation of the β-Al5FeSi with plate-like morphology in higher Fe-containing alloy may hinder further improvement of the plasticity. [ABSTRACT FROM AUTHOR]

High strength and toughness are achieved in the Mg-4.96Gd-2.44Y-0.43Zr alloy by multidirectional impact forging (MDIF). The forged sample has a fine-grained microstructure with an average grain size of ~5.7 µm and a weak non-basal texture, and it was characterized by an optical microscope (OM), scanning electron microscope (SEM), and electron back-scattering diffraction (EBSD). Tensile results exhibit the tensile yield strength (TYS) and static toughness (ST) of as-homogenized alloy dramatically increased after forging and aging, i.e., the TYS increased from 135 − 5 + 4 MPa to 337 − 2 + 2 MPa, and the ST enhanced from 22. 0 − 0.5 + 0.3 MJ/m3 to 50. 4 − 5.4 + 5.3 MJ/m3. Specifically, the forged Mg-Gd-Y-Zr alloy owns higher TYS than that of commercial rolled WE54 (Mg-5.25Y-3.5Nd-0.5Zr) and WE43 (Mg-4.0Y-3.0Nd-0.5Zr) alloys. [ABSTRACT FROM AUTHOR]

• Phase transformation upon cooling Ti 2 AlNb alloy was investigated. • The critical rate to completely depress α 2 and O phases is 0.5 and 4 °C/s, respectively • The phase transformation of B2/β→O occurs in a temperature range of 729–925 °C. • A higher cooling rate makes the phase transformation occur in a narrower temperature range. • The alloy cooled at 0.1 °C/s has the highest microhardness due to the fine but numerous precipitates. Phase transformation and microstructure evolution of a Ti 2 AlNb alloy upon cooling from B2/β phase at rates of 0.02–100 °C/s were investigated by using X-ray diffractometer, scanning electron microscope, and thermal dilatometer. At the lowest cooling rate of 0.02 °C/s, both α 2 and O phases precipitate from the B2/β phase. The precipitation is prior to occur at the grain boundary of the parent phase, which even makes α 2 phase almost disappear from the interior of the grain. Cooling the alloy at a higher rate results in a decreasing amount of the precipitates. The critical rate for the complete depression of α 2 and O phase precipitation is 0.5 °C/s and 4 °C/s, respectively. According to the established continuous cooling transformation (CCT) diagram, the temperature interval for B2/β→O phase transformation decreases with increasing cooling rate. The alloy cooled at the rate of 0.1 °C/s has the highest microhardness for the appropriate size and amount of the precipitated phases. [ABSTRACT FROM AUTHOR]

Ce-based imidazole complex (Ce-IM/ZIF-8) nanoparticles (NPs) were fabricated by doping cerium ions (Ce3+ /Ce4+) in zeolite imidazolate framework-8 (ZIF-8) through a one-pot co-precipitation method. The stimuli-responsive release of Ce3+/Ce4+ species from the Ce-IM/ZIF-8 NPs under acidic conditions was confirmed by UV–Vis spectroscopy. Electrochemical impedance spectroscopy and scanning electron microscope were applied to evaluate the corrosion inhibition efficiency of Ce-IM/ZIF-8 NPs on bare aluminum alloy, and it demonstrates that the released Ce3+/Ce4+, Zn2+ ions and imidazole could absorb on the surface of Al alloy by chelating effect, forming a compact corrosion barrier on the Al substrate. Furthermore, the Ce-IM/ZIF-8 NPs were encapsulated into epoxy (EP) resin to obtain a composite coating, and it is found that when the NPs addition amount was 1 wt%, the EP-based composite coating exhibits excellent corrosion barrier and promising self-healing ability, with its impedance at 0.01 Hz maintaining 2.2 × 108 Ω·cm2 even after 6 cycles of aging tests (720 h), which could be ascribed to the synergistic inhibition of released Ce ions and imidazole molecules on Al substrate beneath the defective coating. A kind of cerium-centered ZIF-8 NPs with surface modified by Ce-imidazole complex (Ce-IM/ZIF-8) was synthesized, which not only realized pH stimuli-responsive release of Ce3+/Ce4+ ions to repair the damaged passive film on Al alloy, but also improved the anti-corrosion property of EP coating. [Display omitted] • Ce-IM decorated ZIF-8 NPs was synthesized by one-pot co-precipitation method. • Ce-IM/ZIF-8 NPs can release Ce3+, Zn2+ ions and imidazole upon acid stimulus. • Ce3+ ions and imidazole present synergistic inhibition effect on Al corrosion. • Ce-IM/ZIF-8 NPs exhibit excellent self-healing ability to EP coating defects. [ABSTRACT FROM AUTHOR]

The hydrogen permeation behavior of novel AlCrFeTiNb, AlCrMoNbZr and AlCrFeMoTi high-entropy alloy (HEA) coatings were investigated. The hydrogen permeability of HEA coatings prepared by magnetron sputtering technology were tested using gas-driven deuterium permeation and electrochemical hydrogen permeation methods. The gas-driven permeation results show that the deuterium permeation resistance of the AlCrFeTiNb coating is the worst because of the unstable structure at a high temperature. Scanning electron microscope (SEM) and X-ray Diffraction (XRD) analysis proved a loose surface morphology of the AlCrFeTiNb coating and demonstrated the formation of iron-based oxides after deuterium permeation experiments. A high content of iron in HEA coating is disadvantageous for improving the hydrogen permeability. Differently, electrochemical hydrogen permeation reveals that the AlCrMoNbZr coating could resist hydrogen permeation better in a corrosive environment (0.2 mol/L KOH solution). The AlCrFeMoTi coating was peeled off after an electrochemical hydrogen permeation test due to the poor corrosion resistance. The hydrogen behavior of HEA coatings was discussed in detail. Our study provides a promising thought on hydrogen permeation of HEA coatings. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation of the tribological behavior of four brass alloys' synthesis by forging (Mm), free-cutting (Md), gravitational casting (Mc), and casting under pressure (Mi). The experiments were conducted on a pin-on-disk tribometer with a load of 200 N, sliding speed of 2.5 m/s, and a sliding distance of 500 m. The microstructure and the worn surfaces were examined with an optical and scanning electron microscope. The results obtained show that the Mc material has less wear resistance related to the presence of voids and an abrasive wear mechanism and the Md material has a stabilized friction coefficient which is related to the uniform distribution of the various phases in the microstructure and the presence of a thick layer of metal transfer on the counter material. [ABSTRACT FROM AUTHOR]

In the most recent decades the introduction of unconventional machining processes allowed the development of micromachining techniques. In this work, the influence of material microstructures on the micromilling process was investigated. Ti6Al4V alloy was selected as workpiece material since it is a very common material for micro applications and because its duplex microstructure can be easily changed by proper thermal treatments. Four different microstructures (namely bimodal, fully equiaxed, fully lamellar and mill annealed) were obtained through recrystallization annealing treatments carried out at different times and temperatures. The mechanical properties of the samples were assessed by microhardness measurements. Nano-indentations were also performed on single grains to understand how the different hardness of phases and structures present in the Ti6Al4V alloy can affect the micromilling process. Microchannels using two flute flat end mills with a diameter equal to 200 μm were realized on the treated samples. Two different feed-per-tooth values were used during the tests. Cutting force, channel shape and burr dimension were investigated. Morphological and energy dispersive spectroscopy (EDS) analyses were performed on tools by means of a scanning electron microscope (SEM): in this way the phenomena mainly influencing the tool status were also identified. Lower cutting forces and reduced tool wear were observed when working fully lamellar microstructures compared to the other ones. [ABSTRACT FROM AUTHOR]

In this study, the planar flow casting (PFC) technique for producing wide amorphous ribbons of FeSiBNbCuAlGe alloy is investigated. Various ribbons of the mentioned alloy were produced through applying different values of wheel speed and ejection pressure. In addition, effects of wheel speed (13, 23, and 33 m/s) on the structure, degree of amorphicity, and surface quality of the ribbons were examined. The results showed that the trends of thickness variation with increasing wheel speed and ejection pressure for FeSiBNbCuAlGe ribbons are in good agreement with what the Bernoulli equation in fluid dynamics predicts for the PFC process. Further, based on x-ray diffraction and differential scanning calorimeter results, it was shown that the degree of amorphicity increases by increasing the wheel speed. Besides, surface roughness measurements and scanning electron microscope micrographs of the ribbons revealed that the surface quality of the prepared ribbons improved by increasing the wheel speed. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to study the effect of the electropolishing time of stencil manufacturing parameters and solder-mask definition methods of PCB pad design parameters on the performance of solder paste stencil printing process for the assembly of 01005 chip components. Design/methodology/approach – During the study, two types of stencils were manufactured for the evaluations: electroformed stencils and electropolished laser-cut stencils. The electroformed stencils were manufactured using the standard electroforming process and their use in the paste printing process was compared against the use of an electropolished laser-cut stencil. The electropolishing performance of the laser-cut stencil was evaluated twice at the following intervals: 100 s and 200 s. The performance of the laser-cut stencil was also evaluated without electropolishing. An optimized process was established after the polished stencil apertures of the laser-cut stencil were inspected. The performance evaluations were made by visually inspecting the quality of the post-surface finishing for the aperture wall and the quality of that post-surface finishing was further checked using a scanning electron microscope. A test board was used in a series of designed experiments to evaluate the solder paste printing process. Findings – The results demonstrated that the length of the electropolishing time had a significant effect on the small stencil's aperture quality and the solder paste's stencil printing performance. In this study, the most effective electropolishing time was 100 s for a stencil thickness of 0.08 mm. The deposited solder paste thickness was significantly better for the enhanced laser-cut stencil with electropolishing compared to the conventional electroformed stencils. In this printing-focused work, print paste thickness measurements were also found to vary across different solder-mask definition methods of printed circuit board pad designs with no change in the size of the stencil aperture. The highest paste value transfer consistently occurred with solder-mask-defined pads, when an electropolished laser-cut stencil was used. Originality/value – Due to important improvements in the quality of the electropolished laser-cut stencil, and based on the results of this experiment, the electropolished laser-cut stencil is strongly recommended for the solder paste printing of fine-pitch and miniature components, especially in comparison to the typical laser-cut stencil. The advantages of implementing a 01005 chip component mass production assembly process include excellent solder paste release, increased solder volume, good manufacture-ability, fast turnaround time, and greater cost saving opportunities. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to investigate the growth behavior and mechanism of Sn whisker induced by RE addition in Sn-Zn-Ga-Pr solder at ambient condition. Design/methodology/approach – By means of aging treatment, FIB and SEM microstructure analysis, the whisker growth behavior was investigated. Findings – It was found that the morphologies of tin whisker are changed during air exposure. After 60 days aging, the average length of the longest whiskers could reach up to 70 μm, some whiskers even can grow to a length of 100 μm. It was discussed that the oxidation of Pr-Sn intermetallics provides driving force for whisker growth. Originality/value – Tin whisker growth is a complex reliability issue for lead-free solder. The current research can be helpful in re-understanding the issue of tin whisker growth as well as an enriched understanding on the effects of REs on lead-free solders. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to study the wear behaviour of eutectic and hypoeutectic Al-Si-Mg-Ce alloys. Design/methodology/approach – The eutectic and hypoeutectic alloys were prepared using permanent mould casting process by varied cerium (Ce) addition in the alloy from 1 to 3 wt%. Dry sliding wear tests were performed against a hardened carbon steel (Fe-2.3%Cr-0.9%C) using a pin-on-disc configuration with fixed sliding speed of 1 m/s and load 50 N at room temperature of ~25 degree. Morphologies of both worn surfaces and collected debris were characterised by a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS). Findings – It was revealed that following the addition of cerium, intermetallic Al4Ce needle-like structure was present in eutectic alloys whereas CeMg2Si2 blocky phase was present in the hypoeutectic alloys. The increasing of Ce addition up to 3.0 wt% in hypoeutectic alloy led to formation of AlCe3 intermetallic phase. The increase in cerium content up to 2 wt% led to higher wear resistance behaviour for both as-cast alloys. Formation of craters and localised plastic deformation were observed on the worn surface of both as-cast alloys, resulting fine particulate and sheet-like wear debris. The wear resistance was found to be higher for hypoeutectic alloy compared to the eutectic alloy containing Ce. Originality/value – An attempt has been made to study the influence of intermetallic compound containing Ce in the Al-Si-Mg alloys on wear behaviour of both as-cast alloys. [ABSTRACT FROM AUTHOR]

The Mg-RE alloys are attractive, constructional materials, especially for aircraft and automotive industry, thanks to combination of low density, good mechanical properties, also at elevated temperature, and good castability and machinability. Present paper contains results of fatigue resistance test carried out on Elektron 21 magnesium alloy, followed by microstructural and fractographical investigation of material after test. The as-cast material has been heat treated according to two different procedures. The fatigue resistance test has been conducted with 106 cycles of uniaxial, sine wave form stress between 9 MPa and 90 MPa. Fractures of specimens, which ruptured during the test, have been investigated with scanning electron microscope. The microstructure of specimens has been investigated with light microscopy. Detrimental effect of casting defects, as inclusions and porosity, on fatigue resistance has been proved. Also the influence of heat treatment's parameters has been described. [ABSTRACT FROM AUTHOR]

Abstract: Microstructures and electrochemical characteristics of La0.7Ce0.3Ni4.2Mn0.9−x Cu0.37(V0.81Fe0.19) x hydrogen storage alloys were investigated. X-ray diffraction and scanning electron microscope results indicate that La0.7Ce0.3Ni4.2Mn0.9Cu0.37 alloy is single LaNi5 phase, and the alloys containing V0.81Fe0.19 consist of LaNi5 matrix phase and V–Mn–Ni secondary phase, and the abundance of secondary phase increases with increasing x value. The activation property of the alloy electrodes is improved by increasing V0.81Fe0.19 content. Maximum discharge capacity of the alloy electrodes changes a little with increasing x value. HRD1200 first increases from 60.4% (x =0) to 70.8% (x =0.10), and then decreases to 56.6% (x =0.20). Cycling stability decreases with increasing x from 0 to 0.20. The adequate substitution of Mn by V0.81Fe0.19 can improve overall electrochemical performances of Co-free high-Mn AB5 alloy. [Copyright &y& Elsevier]

An IN718 alloy coating was prepared by high-power diode laser cladding. 980STA standard heat treatment and direct aging (DA) were employed to improve the properties of this coating. The niobium segregation in the as-deposited coating and the heat-treated coating had been investigated using a scanning electron microscope (SEM) equipped with energy-dispersive X-ray spectroscopy (EDAX). The results showed that 980STA standard heat treatment improved the microhardness of the coating significantly, and Laves concentration was reduced from 30.6 vol pct to about 11.4 vol pct after 980STA. The niobium concentration in Laves of the 980STA-treated coating was higher than that of DA-treated coating and as-deposited coating. Only a small portion of niobium in the coating was precipitated in the form of γ″ during the 980STA heat treatment. The rest of niobium was the alloying element for solid-solution strengthening and the constituent element of Laves. The niobium segregation facilitated the formation of Laves. [ABSTRACT FROM AUTHOR]

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Abstract: A soft buffer layer (BL) between the weld metal (WM) and the parent metal (PM) was introduced in this study. To study the effect of a BL on mechanical properties, two types of joints made from welded high-strength low-alloy (HSLA) specimens with or without a BL were prepared. To investigate the influence of the notch location, the welded HSLA specimens machined with a U-notch in the WM or the PM. These conditions were examined to determine the effects of the BL and the notch location on the fatigue characterizations and the microscopic features of the fatigue-fractured surface. Extended-compact tension (E-CT) specimens were used for all tests. Paris fatigue curves and hardness distributions of the welded HSLA specimens with or without a BL were measured, and relevant scanning electron microscope (SEM) images were taken. The results showed that the presence of a BL significantly improved the fatigue crack growth behavior when a U-notch was in the WM. The notch location greatly influenced the fatigue behavior and the surface features of the fatigue-fractured specimens. [Copyright &y& Elsevier]

In-situ tensile tests have been performed in a dual beam focused ion beam and scanning electron microscope on as-grown and prestrained single-crystal molybdenum-alloy (Mo-alloy) fibers. The fibers had approximately square cross sections with submicron edge lengths and gauge lengths in the range of 9–41 μm. In contrast to previously observed yield strengths near the theoretical strength of 10 GPa in compression tests of ∼1–3-μm long pillars made from similar Mo-alloy single crystals, a wide scatter of yield strengths between 1 and 10 GPa was observed in the as-grown fibers tested in tension. Deformation was dominated by inhomogeneous plastic events, sometimes including the formation of Lüders bands. In contrast, highly prestrained fibers exhibited stable plastic flow, significantly lower yield strengths of ∼1 GPa, and stress–strain behavior very similar to that in compression. A simple, statistical model incorporating the measured dislocation densities is developed to explain why the tension and compression results for the as-grown fibers are different. [ABSTRACT FROM PUBLISHER]