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Hydrogen-induced damage is an inevitable challenge in pipeline safety applications, especially, the fusion welded joints owing to microstructure heterogeneity caused by welding process. In this work, X100 pipeline steel was subjected to friction stir welding (FSW) at rotation rates of 300–600 rpm under water cooling, and the relationship among the microstructure, hydrogen diffusivity, and hydrogen embrittlement (HE) behavior of the nugget zone (NZ) were studied. The NZ at 600 rpm had the highest effective hydrogen diffusion coefficient (D eff) of 2.1 × 10−10 m2/s because of the highest dislocation density and lowest ratio of effective grain boundary. The D eff decreased with decreasing rotation rate due to the decrease of dislocation density and the increase of ratio of effective grain boundary, and the lowest D eff of 1.32 × 10−10 m2/s was obtained at 300 rpm. After hydrogen charging, the tensile strength of all specimens decreased slightly, while the elongation decreased significantly. As the rotation rate decreased, the elongation loss was obviously inhibited, and ultimately a lowest elongation loss of 31.8% was obtained at 300 rpm. The abovementioned excellent mechanical properties were attributed to the fine ferrite/martensite structure, low D eff , and strong {111}//ND texture dramatically inhibiting hydrogen-induced cracking initiation and propagation. • FSW of X100 steel was performed in water cooling, producing defect-free weld. • The diffusion behavior of hydrogen in the NZ was studies. • The effect of hydrogen on deformation and fracture behavior was analyzed. • The NZ with fine ferrite/martensite present high HE resistance. [ABSTRACT FROM AUTHOR]

Abstract The microstructural features and hardness of He-irradiated miscible Cu/Zr crystalline/crystalline nanolaminates with a negative enthalpy of mixing were investigated at room temperature. The distribution of He bubbles within the Cu layers exhibits a high dependence on both layer thickness (h) and ion dose (Φ), while that at the Cu-Zr interfaces is only affected by ion dose. Compared with their as-deposited counterparts, the He-irradiated Cu/Zr nanolaminates tend to manifest radiation-induced solid-state amorphization (RSA), which was induced by ion beam mixing and initiated from crystalline interfaces. The size-dependent hardness of the as-deposited Cu/Zr nanolaminates is elucidated by a transition in the strengthening mechanism from the interfacial barrier strengthening mechanism to the confined layer slip of partials when h is increased. In the He-irradiated Cu/Zr samples, however, the size-dependent hardness is highly related to Φ. Under lower Φ , a nonmonotonically h -dependent irradiation hardening is evident and is associated with a transition from irradiation hardening at large h (≥10 nm) to softening at small h (<10 nm), and the maximum hardening occurs at a critical value of h ≈ 25 nm. In contrast, under higher Φ , the Cu/Zr nanolaminates merely display irradiation softening behavior, with the minimum softening at the critical value of h ≈ 25 nm. The underlying mechanisms are highlighted in terms of dislocation-bubble interactions and RSA. These findings indicate the effects of He ion dose and layer thickness on the He bubble distribution and the interface-mixing of Cu/Zr nanolaminates as well as provide thorough insight into how to tune the He ion dose to manipulate the mechanical response of nanolaminated FCC/HCP materials on a small scale. Graphical abstract Unlabelled Image Highlights • Cu/Zr nanolaminates with smaller layer thickness showed enhanced radiation tolerance. • Large ion dose enhances bubble diameter while reduces bubble spacing in Cu layers. • Cu/Zr nanolaminates suffered size- and dose-dependent amorphization at interfaces. • Low ion dose induces irradiation hardening, while high ion dose induces softening. [ABSTRACT FROM AUTHOR]

Highlights • The Sm(Co bal Fe x Cu 0.06 Zr 0.025) z magnets with different Fe content and z value were investigated. • The correlation of Fe content and z value was established to achieve excellent magnetic properties. • Increasing Fe content promoted the irreversible microstructure evolution in magnets. • Magnetic domain patterns of magnets affected by increasing Fe content indirectly. Abstract Correlation between Fe content and z value on the structural and magnetic properties of the Sm(Co bal Fe x Cu 0.06 Zr 0.025) z magnets (x = 0.20, 0.25, 0.28, and z = 7, 9.5) has been investigated. It is found that the cellular phases in the magnets grow up with increasing Fe content, so the cell boundary phases could hardly form well without enough Sm atoms, resulting in coercivity decreasing. After supplement of Sm content by decreasing z value, cell boundary phases formed continuously, and coercivity was strongly enhanced due to the remarkable concentration gradient of Cu between the 1:5H cell boundary phase and 2:17R cellular phase. It is thus suggested that as the Fe content increases, the z value of magnets need reducing simultaneously in order to keep high coercivity of the magnets. [ABSTRACT FROM AUTHOR]

Nanostructured face-center-cubic/body-center-cubic Cu/(NbMoTaW) multilayers were prepared with equal layer thickness ( h ) spanning from 5 to 100 nm. The hardness was found to increase with reducing h to ~50 nm, following the Hall–Petch relation. Below this critical thickness, a hardness plateau emerged indicative of an interface barrier strengthening mechanism. The high density of misfit dislocations at interfaces facilitates the yielding of high entropy alloy NbMoTaW layers at stresses far less than the strength of Cu/(NbMoTaW) estimated by rule-of-mixture. Compared with reported multilayers, the present Cu/(NbMoTaW) samples show the size-independent hardness at a larger size-range h  < 50 nm. [ABSTRACT FROM AUTHOR]

The correlation between preparation conditions and microstructure as well as magnetic properties were studied for Sm(Co 0.665 Fe 0.25 Cu 0.06 Zr 0.025 ) 7 magnets. Increase of sintering temperature from 1468 to 1493 K promotes the amalgamation of small grains into big ones, resulting in an enlargement of average grain size from 10 to 25 μm and diffusion of Cu from inner grains to Cu-lean grain boundaries. As a result, the demagnetization curve squareness of the magnets improves substantially, leading to a remarkable enhancement of the maximum energy product from 21.3 to 27.1 MGOe. The coercivity of the magnets drops from 25.3 to 16.0 kOe at the same time, which was verified by the increase of the average domain width from 1.1 μm in small grains to 2.5 μm in big grains. It is therefore concluded that tuning of the preparation conditions causes a more homogeneous distribution of Cu, which is crucial for the improvement of magnetic properties. [ABSTRACT FROM AUTHOR]

Microstructure modification induced giant coercivity enhancement from 950 to 1688 kA/m has been achieved in Sm(Co 0.665 Fe 0.25 Cu 0.06 Zr 0.025 ) 7 permanent magnets via Cu powders doping. Microstructure observation shows that in original magnet there are Cu-lean regions along the grain boundary area, where regular cellular structure does not form. After Cu powders doping, most Cu-lean regions disappear. Comparison of magnetic domain reversal between the original magnet and doped magnet indicates that reversed domain propagation was substantially restrained due to the elimination of the Cu-lean region. Moreover, the pinning field increases by 83.3% after Cu doping, having good agreement with coercivity enhancement. [ABSTRACT FROM AUTHOR]

Abstract: In this report, we present results of an irradiation damage study on a pyrochlore compound, Er2Ti2O7. Polycrystalline Er2Ti2O7 was irradiated with 400keV Ne2+ ions at cryogenic temperature (∼77K) to fluences ranging from 2×1018 to 2×1019 ions/m2. Irradiation-induced microstructural evolution was examined using grazing incidence X-ray diffraction (GIXRD) at angles of γ =0.25° and 3°. It was found that the irradiated Er2Ti2O7 undergoes significant lattice swelling before succumbing to a radiation-induced partial amorphization transformation. Both of the extent of the lattice swelling and the lattice disorder of the Er2Ti2O7 increase with increasing Ne ion fluence prior to partial amorphization. We present here a detailed discussion regarding the nature of the defects responsible for the observed lattice swelling and disorder in Er2Ti2O7. [Copyright &y& Elsevier]

Abstract: Ba0.75Sr0.25TiO3 film was epitaxially grown on a (001) LaAlO3 substrate using single-target pulsed laser deposition. The dissociation of misfit and threading dislocations in the epitaxial Ba0.75Sr0.25TiO3 film was investigated using high-resolution transmission electron microscopy (HRTEM). For a misfit dislocation with a Burgers vector of [200], it was shown that it could dissociate into four partial dislocations with Burgers vector of type 1/2 <110>. For the threading dislocations, it was found that they usually coexist with stacking faults. The formation mechanism for the dissociated dislocations was discussed. All the dislocations can relieve the local strain in the Ba0.75Sr0.25TiO3 epitaxial film. [Copyright &y& Elsevier]

Abstract: Cu2O nanocubes (edge length of 6 to 250nm) have been produced by annealing a copper grid at 300°C in air with the presence of tetraoctylammonium bromide (TOAB)-stabilized gold nanoparticles. The microstructure of the nanocubes has been investigated in details using conventional and high-resolution transmission electron microscopy (HRTEM), and chemical analysis has been performed using energy dispersive X-ray spectroscopy (EDS) and electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscopy (STEM). Based on the experimental results, a possible growth mechanism is proposed. [Copyright &y& Elsevier]

Abstract: Platinum (Pt)-modified aluminide coatings were developed by electroplating a thin layer of Pt followed by an industrial vapor phase aluminizing process. The goal of this work was to systematically investigate the effect of critical coating process parameters (such as the electroplated Pt thicknesses, Al contents in Cr–Al nuggets, diffusion heat treatments) and substrates on the final Pt-modified aluminide coatings. Surface morphology and cross-section microstructure of the developed coatings were inspected and compared by using Optical Microscope, Scanning Electron Microscope (SEM) equipped with energy dispersive spectroscopy (EDS). Experimental results showed that the Al and/or Pt increase shall favor the formation of ξ-PtAl2 phase; transformation of ξ-PtAl2 into β-(Ni,Pt)Al phase can be obtained via a heat treatment process; Cr, Co elements in the studied Ni-base superalloy substrates did not show significant influence on coating outer layer microstructure; while substrate elements affect the microstructure of the coating interdiffusion layer. [Copyright &y& Elsevier]

Abstract: An investigation was conducted to synthesize simple β-CoAl or β-(Co,Ni)Al coatings and platinum (Pt)-modified aluminide coatings on cobalt-base superalloys via an industrial vapor phase aluminizing process. Surface morphology and cross-section microstructure of the developed coatings were studied and compared by using optical microscope, scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). Experimental results showed that Al increase in Al–Cr nuggets increases the coating thickness; substrate elements influence the formation of coatings; the increase of the electrodeposited Pt thickness increases the amount of ξ-PtAl2 phase after aluminizing process; and the transformation of ξ-PtAl2 phase into β-(Co,Ni,Pt)Al phase can be obtained via a heat treatment process. [Copyright &y& Elsevier]

Si nanocrystals were formed by implantation of Si+ into SiO2 film on (1 0 0) Si, followed by high-temperature annealing. Transmission electron microscopy (TEM) was used to examine the effect of hydrogen passivation on the microstructure of the Si nanocrystals (nc) in SiO2 film. The size and spatial distribution of the Si nc in both non-passivated and passivated samples were investigated using dark-field imaging technique. It is shown that the size and spatial distribution of the Si nc are much similar for both samples. The concentration of Si nc in SiO2 film was determined from the dark field images taken under different diffraction conditions. Selected area electron diffraction pattern shows that there is no preferential orientation for the Si nc in the SiO2 film. For the passivated sample, the increase of photoluminescence intensity is attributed to the elimination of the optically inactive defects in SiO2 matrix and around the Si nc/SiO2 interface. [Copyright &y& Elsevier]

In this paper, we report microstructural characterization of InAs/GaAs quantum dots grown by molecular beam epitaxy. The InAs islands were annealed in a range of temperatures under Pa flux. Prior to annealing, it is shown that the InAs islands are mainly lens-shaped, mostly vertically self-aligned and coherent to GaAs (1 0 0) substrate. Relaxation by misfit dislocations is occasionally found. Abnormal relaxation is observed in larger islands. Stacking faults in a V-shape are frequently formed in the lateral sides of these regions. No obvious change in island density and self-alignment occurred when the dots are annealed under Pa flux at 300°C. In contrast, remarkable changes took place upon annealing at 350°C. The vertically self-aligned islands disappear, and smooth interfaces were obtained. This morphological transition is argued to result from the replacement of arsenic by phosphorus in the InAs dots. The damage to the crystalinity of the abnormally relaxed regions cannot be removed by the post-growth annealing. The remarkable morphological transition by post-growth annealing under dissimilar anion atmosphere offers another possibility for tuning the dot morphology and hence their electronic properties. [Copyright &y& Elsevier]

Ti alloy clad plate is of great interest for marine and petrochemical industry applications. However, high interfacial bonding is hardly obtained in the Ti alloy clad plate due to the brittle intermetallic compounds (IMCs) forming at the interface. In this study, a Ti-6Al-4V alloy/EH690 steel clad plate was fabricated by vacuum rolling and subsequently tempered to control the mechanical property of the steel substrate. The tempered sorbite appeared in the EH690 steel after quenching and tempering (QT). A decarburized zone, Fe 2 Ti + TiC mixed phases layer, and β-Ti layer were formed at the interface between steel and Ti. The brittle IMCs with high lattice mismatch resulted in a low interfacial strength of 108 MPa. To improve bonding strength, Nb was inserted between Ti and steel as an interlayer, which effectively inhibited the inter-diffusion of Ti, Fe, and C without brittle TiC or Fe-Ti IMCs. A (Ti, Nb) solid solution layer with high plasticity was present at the Nb/Ti interface. Fe 2 Nb and Fe 7 Nb 6 phases were detected at the steel/Nb interface, exhibiting less brittleness and hardness compared to Fe-Ti IMCs. The interfacial shear strength was up to 265 MPa after adding the Nb interlayer, showing a mixed fracture mode of brittleness and ductility. [ABSTRACT FROM AUTHOR]

SiC f /C/Mo/Ti 2 AlNb composites were prepared by foil-fiber-foil (FFF) method and are used as model system to study the effect of solution-ageing treatments on the interface and mechanical properties of SiC fiber-reinforced TiAl-matrix composites. By contrast, SiC f /C/Ti 2 AlNb composites were prepared and heat treated under the same process parameters. The interfacial microstructures of the as-prepared and heat treated composites were investigated by means of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Tensile strength tests of the composites were carried out at room temperature. So the effect of C/Mo duplex coated SiC fibers on the microstructure and tensile behavior of the composites was studied. The results reveal that the interfacial thermal stability and integrity of the SiC f /C/Mo/Ti 2 AlNb composites are much better than those of the SiC f /C/Ti 2 AlNb composites, as the C/Mo duplex coating can reduce the formation of brittle α 2 -phase and relieve the interfacial thermal residual stresses in SiC f /Ti 2 AlNb composites compared with C single coating. After the 1080 °C/1 h/850 °C/20 h heat treatment, the matrix of the SiC f /C/Mo/Ti 2 AlNb composite transformed into mainly B2+O homogenous mixture and a small amount of α 2 phase, and the tensile strength of the composite was tested, which shows that the tensile properties of the composite was maintained after the solution-ageing treatment. [ABSTRACT FROM AUTHOR]

• Fine uniformly dispersed broken precipitates were obtained by ECAP. • The dislocation and broken precipitated phase enhanced the uniform corrosion. • The corrosion rate of AA8176 was reduced at 0 °C with ECAP technology. Electrochemical tests and immersion experiments were employed to investigate the corrosion behaviors of the Al-Fe alloy (AA8176) processed by equal channel angular pressing (ECAP) in 3.5 wt% NaCl solution at different temperature (25 °C and 0 °C). It was worked out that after ECAP, with the reduction of grain size, the fragmentation and uniform distribution of precipitated phases increased the number of pitting corrosion but reduced its size, the increase of grain boundary density and the reduction of precipitated phase aggregation decreased the degree of intergranular corrosion. AA8176 changed from local corrosion to uniform corrosion, which provides a new idea to improve the corrosion resistance of Al-Fe alloys. [ABSTRACT FROM AUTHOR]

Abstract: The (1− x) La0.67Ca0.33MnO3/xCuFe2O4 (x =0, 0.04, 0.07, 0.10 and 0.15) composites have been prepared and investigated systematically for their microstructure, electrical and magnetic properties. The X-ray diffraction and scanning electronic microscopy analysis reveal that both La0.67Ca0.33MnO3 (LCMO) and CuFe2O4 phases are distributed in the composites. Compared with pure LCMO, an obvious enhancement of magnetoresistance is observed over a wide temperature range for the composites. Under 3T field, the magnetoresistance rises from a base value 44.5% for pure LCMO, to a maximum value of 66.7% for x =0.1 composite. Meanwhile, a weak temperature-dependent MR platform is observed in the temperature range from 210K to 240K. The MR enhancement is discussed in terms of spin-polarized intergrain tunneling due to enhanced magnetic disorder and magnetic coupling near boundaries between LCMO and CuFe2O4 grains. [Copyright &y& Elsevier]

Abstract: Bi0.4Ca0.6MnO3 (BCMO) film with a thickness of 110nm was epitaxially grown on a (110) SrTiO3 (STO) substrate using pulsed laser ablation technique. The microstructure of the epitaxial films was investigated by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) in details. Two different kinds of dislocations, one being perpendicular to the BCMO/STO interface, the other being parallel to the interface, have been commonly observed. The formation mechanism for these dislocations has been discussed. All the dislocations are thought to relieve the local strain in the epitaxial film. [Copyright &y& Elsevier]

High-entropy FeCoNiAl 0.5 alloy was produced and subjected to heat treatment at different temperatures (400, 600, and 800 °C). The microstructure evolution, magnetic properties and mechanical properties of the alloy were found to be highly dependent on the annealing temperature. The as-cast alloy was composed of FeCoNi-riched matrix (face-centered cubic structure) and the Al-riched region (body-centered cubic structure). After annealed at 400 °C, Al–Ni-based ferromagnetic rod-like precipitates with body-centered cubic structure were abundantly produced within the matrix, improving saturation magnetization (M s), coercivity (H c) and hardness. Increasing the annealing temperature to 600 °C, not only gave rise to a higher number density of the rod-like precipitates, but also to the formation of some nanosized spherical precipitates. This microstructure feature is more effective in strengthening the material (achieving a peak hardness of ~304 HV) but at the same time results in slight declination of M s and H c. When the annealing temperature was up to 800 °C, the most strengthening nanoscale precipitates dissolved, and the hardness of the alloy was reduced accordingly. The main strengthening mechanisms are discussed, and a good combination of mechanical and magnetic properties under optimized heat treatment may be available. [ABSTRACT FROM AUTHOR]

Abstract It is rather difficult for Ti alloy welds to be superplastic formed due to their low superplasticity and high flow stress. In this study, the Ti-6Al-4V alloy after hydrogenation with 0.2 wt% hydrogen was subjected to friction stir welding (FSW). The superplastic behavior of the FSW joint was investigated. The stir zone with a fine lamellar microstructure exhibited a largest elongation of 660% at 825 °C and 3 × 10−3 s−1. Besides, the stir zone showed a similar superplasticity of close to 600% to the base material at 825 °C, 3 × 10−4−1 × 10−3 s−1. It is the first report on the superplasticity of FSW Ti alloy joints with hydrogenation. Compared to the FSW Ti-6Al-4V alloy joint without hydrogenation, the hydrogenated FSW joint showed superior superplastic properties, including a high elongation, less than a half flow stress and lower superplastic temperature. These superior superplastic properties were mainly attributed to the globularization of the lamellar microstructure and the high fraction of β phase induced by the hydrogen element. This study provides an effective way to reduce the difficulty of practical superplastic forming for Ti alloy welds, although a dehydrogenation process is still needed to avoid hydrogen embrittlement. Graphical abstract Image 1 Highlights • It is the first time to report the superplastic behavior of hydrogenated friction stir welded Ti alloy joints. • A largest elongation of 660% was achieved at 825 °C, 3 × 10−3 s−1. • The similar superplasticity of ∼600% was achieved for the stir zone and base material at 825 °C, 3 × 10−4-1 × 10−3 s−1. • Hydrogenation largely reduced the flow stress and the optimum superplastic temperature of the joint. • The superior superplastic properties were attributed to the globularization of the lamellae and a large fraction of β phase. [ABSTRACT FROM AUTHOR]

Grain boundary (GB) engineering via alloying opens a pathway to design the interfaces in alloys for tuning their mechanical properties, thus it is quite critical to determine the optimum addition of alloying element. Here, we prepared immiscible Cu-Cr alloyed thin films by non-equilibrium magnetron sputtering deposition to study Cr alloying effects on the microstructure and mechanical properties of Cu thin films. It is found that Cr doping can notably refine the grains and promote the formation of fully nanotwinned columnar grains at low Cr volume concentrations (≤∼3.7 at.%) associated with the average GB Cr concentrations ≤ ∼15 at.%, beyond which the formation of nanotwins is significantly suppressed. The role of Cr atoms/clusters played in the twinning process is rationalized in terms of dislocation rebound-promotion mechanism. Importantly, a maximum hardness is discovered at the optimum Cr addition of ∼2.0 at.%. The Cr concentration-dependent hardness of Cu-Cr alloyed films was quantified by a combined strengthening model. The achievement of the maximum hardness was related to the greatest GB solute segregation-induced strength contribution. It is further uncovered that the Cu-Cr system exhibits strain rate sensitivity (SRS, m ) monotonically reduced with increasing the Cr concentration, ranging from a positive m of 0.0314 (for pure Cu) to a negative m of −0.0245, which is attributed to a competition between the dislocation-boundary interactions (increasing m ) and the dislocation-solute atoms interactions (decreasing m ). These findings provide valuable insights into tuning the composition of alloyed thin films to achieve optimized mechanical performance. [ABSTRACT FROM AUTHOR]

Tuning the microstructure to optimize the mechanical performance of nanocrystalline Cu thin films via the alloying strategy is quite important for their application in microdevices. In this work, we prepared nanocrystalline miscible Cu-Ti and immiscible Cu-Mo alloyed thin films to investigate alloying effects on the microstructure and mechanical properties of Cu thin films in terms of mixing enthalpies. It is found that the dopants of both Ti and Mo can notably refine the grains, and in particular promote the formation of nanotwins below a critical content of solute, beyond which the formation of nanotwins is notably suppressed. The nonmonotonic solute concentration-dependent twinning behavior observed in Cu-Ti and Cu-Mo alloyed thin films is explained by the coupling effects between grain size and grain boundary segregated dopants that affects the stimulated slip process of partials. The increased hardness of both Cu-Ti and Cu-Mo systems with increasing the solute contents are quantitatively explained by combining several strengthening mechanisms, including solid solution strengthening, grain/twin boundary (GB/TB) strengthening, solute segregation-induced strengthening. It unexpectedly appears that with increasing the solute contents, the Cu-Ti system exhibits monotonically reduced positive strain rate sensitivity (SRS, m ), whereas the Cu-Mo system manifests almost constant negative SRS. The fundamental difference in SRS m between Cu-Ti and Cu-Mo is rationalized in terms of the interactions between solute atomic clusters and dislocations based on the cross-core diffusion mechanism. [ABSTRACT FROM AUTHOR]

The magnetron sputtering technique was employed to prepare Zr-alloyed Cu thin films with Zr addition ranging from 0 to 7.0 at.%. Microstructure evolution with Zr doping was characterized by using the transmission electron microscope and atom probe tomography. Plastic deformation characteristics (hardness, strain rate sensitivity and activation volume) of the Cu-Zr alloyed films were examined by using nanoindentation testing. Significant Zr doping effects on the microstructure were clearly uncovered that (i) the Zr segregated at grain boundaries and tuned the grain boundary structure. With increasing the Zr addition, CuZr amorphous particles at grain boundaries (3.0 at.% Zr) and even three dimensional CuZr amorphous grain boundary network (7.0 at.% Zr) were formed; (ii) the grains (size and morphology) and nanotwins were notably influenced by the Zr doping. In particular, the nanotwin thickness was reduced from ∼25 nm in the pure Cu film down to ∼5 nm in the Cu-Zr alloyed films. Accompanied with the microstructure evolution, the Cu-Zr thin films displayed hardness and strain rate sensitivity highly sensitive to the Zr doping, i.e. , hardness increasing while strain rate sensitivity decreasing with raising the Zr addition. The strengthening and deformation mechanisms were discussed in terms of the microstructure-property relationship. Three regimes were divided within the studied Zr doping range: grain/nanotwin boundary-dominated strengthening mechanism in the regime I of pure Cu film, dislocation nucleation-controlled nanotwin softening mechanism in the regime II of Zr addition ≤3.0 at.%, and intergranular amorphous layer-mediated strengthening mechanism in the regime III of Zr addition up to 7.0 at.%. In addition, the reduction in strain rate sensitivity with Zr doping was quantitatively described by adopting a model that involves the thermally activated partials depinning mechanism based on the effective dislocation segment length. [ABSTRACT FROM AUTHOR]

Nanoindentation methodology was used to investigate the plastic deformation characteristics, including the hardness ( H ), strain rate sensitivity (SRS, m ) and activation volume ( V * ), of Cu/Mo nanostructured metallic multilayers (NMMs) with equal layer thickness ( h ) spanning from 10 to 200 nm before and after He-implantation at room temperature. Compared with the as-deposited Cu/Mo NMMs, the irradiated Cu/Mo samples exhibited the enhanced hardness particularly at great h , which is caused by the bubble-hardening effect. Unlike the as-deposited Cu/Mo NMMs displayed a monotonic increase in SRS (or a monotonic decrease in activation volume) with reducing h , the irradiated Cu/Mo samples manifested an unexpected non-monotonic variation in SRS as well as in activation volume. It was clearly unveiled that the SRS of irradiated Cu/Mo firstly decreased with reducing h down to a critical size of ~50 nm and subsequently increased with further reducing h , leaving a minimum value at the critical h . These phenomena are rationalized by considering a competition between dislocation-boundary and dislocation-bubble interactions. A thermally activated model based on the depinning process of bowed-out partial dislocations was employed to quantitatively account for the size-dependent SRS of Cu/Mo NMMs before and after irradiation. Our findings not only provide fundamental understanding of the effects of radiation-induced defects on plastic characteristics of NMMs, but also offer guidance for their microstructure sensitive design for performance optimization at extremes. [ABSTRACT FROM AUTHOR]

Er-stuffed pyrochlore series Er 2 (Ti 2− x Er x )O 7− x /2 ( x = 0, 0.162, 0.286, 0.424 and 0.667) were synthesized using conventional ceramic processing procedures. The structure of Er 2 (Ti 2− x Er x )O 7− x /2 is effectively tailored by the Er stuffing level ( x ). In order to study the radiation effect of Er-stuffed pyrochlores, irradiation experiments were performed with 400 keV Ne 2+ ions to fluences ranging from 5 × 10 14 to 3.0 × 10 15 ions/cm 2 at cryogenic condition. Irradiation induced microstructural evolution was examined using a grazing incidence X-ray diffraction technique. It is found that the irradiated layer of Er 2 (Ti 2− x Er x )O 7− x /2 undergoes significant lattice disordering and swelling at fluences of ⩽1.5 × 10 15 ions/cm 2 and amorphization at fluences of ⩾1.5 × 10 15 ions/cm 2 . The radiation effect depends strongly on the chemical compositions of the samples. Both the lattice swelling percentage and the amorphous fraction decrease with increasing x . The experimental results are discussed in the context of cation antisite defect. The defect formation energy which varies as a function of x is responsible for the difference in the structural behaviors of Er 2 (Ti 2− x Er x )O 7− x /2 under 400 keV Ne 2+ ion irradiation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Poly(St-AA)/Fe3O4 microspheres were prepared via miniemulsion copolymerization. [•] The effect of crosslinker on the final particle morphology was studied. [•] The adsorbed weight of BSA at different adsorption time and pH were investigated. [•] The adsorbed weight of BSA was increased with the content of AA. [Copyright &y& Elsevier]

Abstract: Interface effects on ion-irradiation tolerance properties are investigated in nanolayered TiN/AlN films with individual layer thickness varied from 5nm to 50nm, prepared by pulsed laser deposition. Evolution of the microstructure and hardness of the multilayer films are examined on the specimens before and after He ion-implantation to a fluence of 4×1020 m−2 at 50keV. The suppression of amorphization in AlN layers and the reduction of radiation-induced softening are observed in all nanolayer films. A clear size-dependent radiation tolerance characteristic is observed in the nanolayer films, i.e., the samples with the optimum layer thickness from 10nm to 20nm show the best ion irradiation tolerance properties, and a critical layer thickness of more than 5nm is necessary to prevent severe intermixing. This study suggests that both the interface characteristics and the critical length scale (layer thickness) contribute to the reduction of the radiation-induced damages in nitride-based ceramic materials. [Copyright &y& Elsevier]

Abstract: We compare the evolution of microstructure and mechanical properties of Ag/Ni multilayers of varying layer thickness (1–200nm) subjected to helium ion and proton irradiation at room temperature to similar dose, ∼2 displacements-per-atom on average. Layer structure remained intact after both types of irradiation although defects accumulated in the layers are different. Helium bubbles were the major defects in helium ion irradiated films, while dislocation loops were ubiquitous in proton irradiated multilayers. In He ion irradiated multilayers, radiation hardening was greater than that in proton irradiated specimens, and the magnitude of hardening decreased with decreasing individual layer thickness. In comparison no size dependent hardening was observed in proton irradiated films. Mechanisms of irradiation induced hardening were discussed. [Copyright &y& Elsevier]

Abstract: Manufacturing of microstructured mold surfaces was realized by the micromachining of thick sol–gel silica hybrid coatings. The films were deposited onto pre-machined steel molds by spin coating using NaOH-catalyzed sols from organosilicate precursors. The effect of the sol synthesis and the heat treatment on the mechanical and chemical properties of these films was studied in order to develop thick and crack-free films with appropriate properties for micromachining with diamond cutting tools. The hardness was measured by nanoindentation as a function of the heat treatment temperature. The transition from soft organic gel films to hard glass-like films due to the thermal treatment was characterized by X-ray photoelectron spectroscopy, elastic recoil detection, and Raman and infrared spectroscopies. The films from NaOH catalyzed sols showed a complex transition from aliphatic carbon originating from hydrocarbon groups to carbonates, carboxylates and disordered carbon clusters. [Copyright &y& Elsevier]

Abstract: SiCp/Mg–Zn–Ca composite fabricated by stir casting was extruded at three different temperatures. Firstly, hot extrusion significantly improved particle distribution and refined the grains of the matrix. Even, nano-grains were observed in the composite extruded at 250°C. Secondly, extrusion evidently refined the size of the second phases, but also changed the distribution of the second phases. Extrusion temperatures obviously affected the size and distribution of the second phases. Thirdly, the interface between SiCp and matrix was also modified by hot extrusion. Finally, all as-extruded composites possessed good mechanical properties. Below 150°C, the UTS was very high in the extruded composites, but their strengths decreased sharply above 150°C. [Copyright &y& Elsevier]

Abstract: Bi0.4Ca0.6MnO3 (BCMO) film was epitaxially grown on a (110) SrTiO3 substrate using the pulsed laser ablation technique. The morphologies of the epitaxial films with different thicknesses were considerably different. For the Bi0.4Ca0.6MnO3 epitaxial film with a thickness of 10nm, the morphology was more like islands. As the film thickness increased to 40nm, the island became smaller, and disappeared when the film thickness reached 110nm. The growth mechanism of the epitaxial films depends on film thickness, which has been discussed. The results will shed light on the formation mechanism of BCMO epitaxial films. [Copyright &y& Elsevier]

Abstract: We have systematically studied Ar-ion-milling-induced microstructural evolution in Cu50Zr45Ti5 metallic glass (MG) during specimen preparation for transmission electron microscopy (TEM). We have observed the formation of a Cu10Zr7 intermetallic phase in samples prepared using low energy ion milling (2keV) but without evident crystallization. We also observed the formation of nanocrystalline Cu10Zr7 phase (with a possibility of being mixed with other minor phases) in samples prepared using high energy ion milling (⩾3keV). In contrast, the MG samples remained in the glassy state without any microstructural changes when prepared by either electropolishing or low energy ion milling with liquid nitrogen cooling (2keV). Further, our study suggests that chemical decomposition might be a necessary intermediate stage for crystallization. In situ TEM electron irradiation shows ion-milling-induced phase segregation and preferred nanocrystallization in the precipitated regions. [Copyright &y& Elsevier]

Microstructural evolution of Zr55Cu30Al10Ni5 and Cu50Zr45Ti5 metallic glasses under 200keV electron irradiation has been studied in situ by transmission electron microscopy. Zr55Cu30Al10Ni5, which has a wider supercooled liquid region, is found to be stable under electron irradiation and no crystallization is observed up to an irradiation fluence of 8.7×1026 electronsm−2. In contrast, nanometer size crystalline Cu10Zr7 phases are formed in Cu50Zr45Ti5 under electron irradiation. The partial crystallization is attributed to irradiation enhanced atomic mobility. [Copyright &y& Elsevier]

Abstract: The microstructure and magnetic properties have been investigated systematically for Sn1−x Mn x O2 (0≤ x ≤7%) nanoparticles synthesized by chemical co-precipitation method. The X-ray diffraction reveals that all samples are pure rutile-type tetragonal phase and the cell parameters a and c decrease monotonously with the increase of Mn content, indicated that Mn ions substitute into the lattice of SnO2. X-ray photoelectron suggests that Mn ions behave as the mixture state of Mn3+ and Mn4+ in samples. Magnetic investigations demonstrate that magnetic properties strongly depend on both the sintering temperature and doping content. No ferromagnetism is observed for samples sintered at high temperature (T S =800°C), irrespective of the doping content. In contrast, the samples sintered at low temperature (T S =450°C) possess room temperature ferromagnetism when the doping content is below 5%. A plausible explanation of the magnetic properties is presented in terms of bound magnetic polaron model. [Copyright &y& Elsevier]

High entropy alloys (HEAs) have attracted extensive attention due to their excellent properties in harsh environments. In this work, we prepare HEA/Cu (HEA = FeCoCrNi) nanotwinned nanolaminates (NTNLs) with equal individual layer thickness (h) and study the He-ion irradiation effects on their deformation behavior and mechanical properties. With decreasing h the microstructure of HEA/Cu NTNLs transits from the nanolayered structure with nanotwins confined in the isolated layers at large h ≥ 25 nm to the columnar grained single crystal-like structure with nanotwins penetrated across the coherent layer interface(s) at small h < 25 nm. Compared with the as-deposited HEA/Cu NTNLs showing notable detwinning behavior, in particular at small h , the nanotwins in irradiated samples are difficult to detwin owing to the He defects pinning effect on twin boundaries. It appears that both as-deposited and irradiated HEA/Cu NTNLs manifest the trend of "smaller is stronger". Unlike the reported monotonically increased/reduced irradiation hardening with h in conventional bimetal nanolaminates, a minimum irradiation hardening occurs in the present HEA/Cu NTNLs. Unexpectedly, the as-deposited HEA/Cu NTNLs manifest positive reduced strain rate sensitivity (SRS) m with decreasing h , while their irradiated siblings exhibit the transition from positive to negative SRS m. The size-dependent mechanical properties of HEA/Cu NTNLs are rationalized by the partial-based mechanism in combination with the stability of nanotwins. • Nanotwins disappear in deformed Cu/HEA NTNLs but are stabilized by He+ irradiation. • Irradiated Cu/HEA NTNLs manifest a unusually non-monotonic irradiation hardening. • As-deposited Cu/HEA NTNLs show unusually reduced SRS as decreasing layer thickness h. • Irradiated Cu/HEA NTNLs show the positive-to-negative SRS transition as decreasing h. [ABSTRACT FROM AUTHOR]