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Recently, magnetic metal-semiconductor nanocomposite films with a uniform superparamagnetic structure have attracted increasing interest in negative magnetoresistance (MR) properties at room temperature (RT). In this work, we have designed and prepared an original nonuniform structure with coexistence of size-distributed ferromagnetic Co clusters and superparamagnetic Co particles in Co–ZnO nanocomposite films, with Co content between 41 and 65 at.%. The film with 49 at.% Co shows a large RT negative MR with a maximum value of over 9.5%. As Co content increasing, the ferromagnetic Co clusters grow both in quantity and size. Meanwhile, the curves of normalized MR become broader, and the peaks of the normalized MR field sensitivity (FS) shift to higher fields. It is noteworthy that the increase in ferromagnetic Co clusters can effectively modulate the MR FS, which is reasonably explained by establishing a mechanism model with the localized magnetization flux effect and inhomogeneous current paths based on size-distributed ferromagnetic Co clusters. This nonuniform structure can be extended to other nanocomposite materials for the modulation of MR FS by microstructure control in various application scenarios. [ABSTRACT FROM AUTHOR]

Laser surface quenching technology was used to modify the surface microstructure of as-cast Ni-Al bronze (NAB). The modified microstructure was studied by scanning electron microscopy (SEM), and the effect of laser process parameters on microstructure evolution was investigated. It was found that a fine-grained zone with fully β phase microstructure formed on the surface of NAB. The depth of the fine-grained zone increased with the increase of laser power, and surface melting occurred when the power reached a threshold value. Laser scanning at a low rate caused the coarsening of grain boundary, while too high rate led to incomplete quenching. Spot overlap ratio determined the microstructure of the superimposed area, and unsuitable ratio would cause bulky κ precipitation at the grain boundary or incomplete transformation from α phase to β phase. [ABSTRACT FROM AUTHOR]

The cross-sectional depth microstructure profiles for a multilayer AA4045/AA3003*/AA4045 brazed sheet were observed and determined by focused ion beam-transmission electron microscopy (FIB-TEM) and energy dispersive spectrometer (EDS). The corrosion propagation of the multilayer brazed sheet in the sea water acidified accelerated test (SWAAT) was investigated by electrochemical impedance spectroscopy (EIS). The measured corrosion potentials of different layers of the multilayer aluminum sheet have been carried out according to ASTM G69-97 standard test method. To reveal the effect of the alloying elements on corrosion behavior, the theoretical corrosion potential of the band of dense precipitates (BDP) zone and core materials was also calculated according to the theoretical corrosion potential model. The electrochemical results showed that there were potential differences between the precipitates free zone (PFZ) and BDP zone as well as BDP zone and the core materials. The EIS test and equivalent circuits (EC) suggested that the capacitive time constant at low frequencies correspond to the corrosion of the BDP zone in the form of exfoliation corrosion. The corrosion propagation process could be identified into four stages: the dissolution of the eutectic α -Al in the re-solidified cladding in the form of pitting corrosion; the corrosion of the primary α -Al grain boundaries in the form of inter-granular corrosion (IGC); the corrosion of the BDP zone in the form of exfoliation corrosion; and the corrosion of the core material in the form of IGC. [ABSTRACT FROM AUTHOR]

The microstructures of AA4045/AA3003Mod./AA4045 aluminum-brazed sheet were observed and determined by stereoscopic digital microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectrometer (EDS). The corrosion process of the brazed sheet in the exfoliation corrosion (EXCO) solution was investigated by electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) techniques. The results showed that the brazed sheet was composed of the Al-Si eutectic zone, the precipitates-free zone (PFZ), the band of dense precipitates zone (BDP) and the core material. With the immersion time increased, the capacitive time constant in EIS plot changed from one time constant through two unclear time constants to two clear time constants, and then went back to two unclear time constants again. The maximum relative energy in energy distribution plot (EDP) changed from small scales through middle scales to large scales, and then went back to middle scales. The corrosion process could be divided into four stages: the dissolution of the eutectic α -Al in the resolidified clad in the form of pitting corrosion; the corrosion of the primary α -Al grain boundaries in the form of intergranular corrosion (IGC); the corrosion of the BDP zone in the form of exfoliation corrosion; and the corrosion of the core material in the form of IGC. [ABSTRACT FROM AUTHOR]

Microarc oxidized coatings on Ti6Al4V alloy are produced in a basic Na2SiO3-(NaPO3)6-NaAlO2 electrolyte with different concentrations of sodium tungstate. The effects of sodium tungstate on the characteristics of the coating are investigated through current-time response, microstructure, composition, hardness, bonding strength and antifriction measurements. The coating is mainly composed of Al2TiO5, TiO2, Al2O3 and amorphous substances regardless of the concentration of sodium tungstate. The sodium tungstate is transformed into trace amounts of WO3, which significantly promotes the growth of the coatings. The bonding strength and antifriction performance of the coatings are enhanced with the concentration of sodium tungstate less than 4 g/L, whereas excessive sodium tungstate results in a coarse outer layer with more microdefects, which deteriorates the wear resistance of the coating. Based on the results of scratch and wear test with energy-dispersive x-ray spectroscopy of the worn surface and debris, the optimal concentration of sodium tungstate doped into the electrolyte is identified, and this concentration yields superior tribological property. Excellent wear resistance is achieved by combining a high bonding strength and hardness with a less defective outer layer. [ABSTRACT FROM AUTHOR]

K4Fe(CN)6 was used to improve the microstructure and properties of copper deposits obtained from hypophosphite baths. In electroless copper plating solutions using hypophosphite as the reducing agent, nickel ions (0.0038 M with Ni2+/Cu2+ mole ratio 0.12) was used to catalyze hypophosphite oxidation. However, the color of the copper deposits was dark or brown and its resistivity was much higher than that obtained in formaldehyde baths. The effects of K4Fe(CN)6 on the deposit composition, resistivity, structure, morphology and the electrochemical reactions of hypophosphite (oxidation) and cupric ion (reduction) have been investigated. The deposition rate and the resistivity of the copper deposits decreased significantly with the addition of K4Fe(CN)6 to the plating solution and the color of the deposits changed from dark-brown to copper-bright with improved uniformity. The nickel and phosphorus content in the deposits also decreased slightly with the use of K4Fe(CN)6. Smaller crystallite size and higher (111) plane orientation were obtained by addition of K4Fe(CN)6. The electrochemical current–voltage results show that K4Fe(CN)6 inhibited the catalytic oxidation of hypophosphite at active nickel sites and reduced the reduction reaction of cupric ions on the deposit surface by adsorption on the electrode. This results in lower deposition rate and a decrease in the mole ratio of NaH2PO2/CuSO4 consumed during plating. [ABSTRACT FROM AUTHOR]

• Co-ZnO non-uniform film structure is realized by adjusting sputtering pressure. • Suppression of Co clusters is obtained at high sputtering pressure. • High magnetoresistance and low-field sensitivity are simultaneously achieved. Co-ZnO metal–semiconductor nanocomposite films have become the focus of attention in recent years since their magnetoresistance (MR) effect at room temperature (RT). In this study, non-uniform Co-ZnO nanocomposite films were prepared by magnetron co-sputtering method. With sputtering pressure increasing, the formation of ferromagnetic Co clusters is suppressed effectively, and the metallic-state superparamagnetic Co particles are dispersed, which form the tunneling transport paths in the Co-ZnO films at high Co content. As the sputtering pressure increases from 0.3 Pa to 1.2 Pa, the RT -MR value of the films increases from 0.41 % to 11.85 %, and the saturation magnetization of the films rises from 6.3 kGs to 7.3 kGs and then decreases to 6.7 kGs. It is noteworthy that the low-field MR field sensitivity at 1000 Oe is enhanced by about 10 times from 0.5 Pa to 1.2 Pa. This provides a reference for the application of low-magnetic field detectors. [ABSTRACT FROM AUTHOR]

Abstract: In electroless copper plating baths using hypophosphite as the reducing agent, nickel ions was used to catalyze hypophosphite oxidation. However, the color of the copper deposits was dark or brown and the electrical resistivity was much higher than that obtained from formaldehyde baths. Polyethylene glycol (PEG) and K4Fe(CN)6 were used to improve the microstructure and properties of copper deposits obtained from electroless copper plating bath using hypophosphite as the reducing agent. The effects of PEG concentration on the deposition rate, the microstructure, morphology and electrical resistivity of the copper deposits, and the electrochemical reactions of hypophosphite (oxidation) and cupric ion (reduction) were investigated. The traces of hydrogen escaping from the deposits surface disappeared and the color of the copper deposits changed from dark-brown to dark red when the PEG concentration was 1.67×10−5 M or more. The deposition rate increased and the electrical resistivity of the copper deposits decreased slightly with the addition of PEG to the plating solution. The electrical resistivity of copper deposits decreased to 2.85μΩ cm with 1.67×10−5 M PEG and 4.70×10−6 M K4Fe(CN)6 in the bath. Larger grain size and higher (220) plane orientation were obtained with the increase of PEG concentration in the bath. The electrochemical current–voltage results showed that PEG accelerated the catalytic oxidation of hypophosphite at active nickel sites and had little effect on the reduction reaction of cupric ions on the deposit surface by adsorption on the electrode. [Copyright &y& Elsevier]

Abstract: Ni–SiC metal matrix composites with two kinds of SiC content were prepared by electroforming in a nickel sulphamate bath. Tensile strength and microstructure of the composites before and after heat treatment were investigated. The maximum of tensile strength was obtained after heat treatment at 300 °C×24 h. The values were 641 N/mm2 and 701 N/mm2 respectively. The complete reaction between nickel and SiC particles can produce shrinkage pores in the interface. The volume of shrinkage pores was equal to 8% of the volume of SiC particles in the composites. The interfacial reaction products were composed of Ni3Si and a little amount of Ni31Si12 after heat treatment at 600 °C×24 h. The fracture evolution went though microcracks initiation, growth and coalescence. Cracking of the matrix, debonding of Ni–SiC interfaces and cracking of particles were three types of cracking modes for Ni–SiC composites. [Copyright &y& Elsevier]

Graphical abstract Abstract Surfacing layers on H13 hot-working die steel for the repair and manufacture of structural components using submerged arc welding (SAW) have been tempered at 350 ℃, 450 ℃, 550 ℃ and 650 ℃ for 2 h. The impact toughness of specimens tempered at 350 ℃ were increased significantly, with their microhardness and wear resistance improved due to a decrease in welding defects and secondary hardening caused by the precipitation of carbide. Tempering at 450 ℃ resulted in refinement of microstructure, with a large amount of tempered martensite being formed that significantly improved the microhardness, wear resistance and impact toughness. However, it was found that these mechanical properties were decreased at 550 ℃ due to grain growth. Formation of large numbers of carbide particles resulted in hard abrasive specimens that were difficult to cut, resulted in an overall increase in wear resistance when the specimens were tempered at 650 ℃. [ABSTRACT FROM AUTHOR]

Abstract To extend the applications of 316L stainless steel in corrosive environments and correlate the corrosion resistance with composition and microstructure, homogeneous Cr-rich layer with the thickness of 75 μm was fabricated on 316L stainless steel by pack chromizing and post heat treatment. The chromizing layer was mainly composed of Fe Cr solid solution. Post heat treatment eliminated the precipitates and Cr-depletion in the chromizing layer. The corrosion behaviors were studied by electrochemical measurements and corrosion morphology observation. The pitting corrosion in Cl− containing solutions was avoided after chromizing treatment, which was ascribed to the reduced sensitivity of Cr-rich surface to Cl− ions. The higher Cr concentration in the modified layer also improved the long-term stability of corrosion resistance. After immersion in NaCl solution for 24 days, the charge transfer resistance of chromizing sample was higher than that of 316L by a factor of 8.19. In addition, the free corrosion potential shifted to the positive direction after post heat treatment, and the corrosion current density was also reduced to 0.066 μA/cm2. The further improvement on anticorrosion performance was attributed to the homogeneous microstructure. Graphical abstract Unlabelled Image Highlights • The Cr-rich layer was fabricated by high-temperature pack chromizing treatment. • The chromizing layer provided enhanced pitting corrosion resistance for 316L SS. • The correlation between corrosion resistance and composition/microstructure was studied. • Post heat treatment homogenized the microstructure and further improved the performance. [ABSTRACT FROM AUTHOR]

Microstructure evolution of the nickel-aluminum bronze alloy was studied by heat treatment, including annealing, normalizing, quenching and aging. The microstructure was refined and homogenized after quenching or quenching/aging at 450 ℃, which can eliminate selective phase corrosion effectively. Compared with the current production process, static corrosion rate reduced about 50%, due to the rapid formation of a protective film. In addition, cavitation corrosion rate reduced by a factor of 4.9 and 7.9 for the quenched and quenched/aged at 450 ℃ samples, respectively. This can be attributed to the improved hardness and weakened synergy between corrosion and mechanical attack. [ABSTRACT FROM AUTHOR]

As-cast nickel-aluminum bronze is prone to suffering selective phase corrosion in marine environments. To solve this problem, chromium was introduced via ion implantation to modify its surface microstructure, which was characterized by high-resolution transmission electron microscopy and auger electron spectroscopy. The corrosion behavior was studied by electrochemical measurements and salt spray test. It was found that the inherent selective phase corrosion in as-cast NAB was inhibited effectively when the implantation fluence was 5 × 10 17 ions/cm 2 . The improved corrosion resistance after ion implantation was believed to stem from the rapid formation of a more protective film containing chromium oxides and hydroxides. [ABSTRACT FROM AUTHOR]

Co–ZnO metal-semiconductor nanocomposite films have drawn a growing number of attention due to their significant room temperature (RT) magnetoresistance (MR) effect. In this paper, Co–ZnO non-uniform nanocomposite films with high crystallinity of ZnO matrix have been prepared by controlling substrate temperature. With the increase of substrate temperature, the Co particles grow and gradually aggregated into ferromagnetic clusters, which leads to an increase in saturation magnetization (M s) from 5.8 to 6.7 kGs. Moreover, the growth of ferromagnetic clusters results in the formation of cluster-particle current paths and isolated magnetic particles, which have less contribution to the MR, causing the separation between MR curve and -(M/M s)2 curve. This phenomenon induces a broadening of the MR curve, which modulates the shift of the MR field sensitivity (FS) peak toward higher fields. When the substrate temperature is 250 °C, high ZnO matrix crystallinity, -MR value (2.6%) and effective modulation of MR FS in Co–ZnO non-uniform nanocomposite films can be achieved simultaneously. It provides a reference for the application and modification of Co–ZnO MR devices. • The highlights of this work are: • Co–ZnO non-uniform film structure is obtained by adjusting substrate temperature. • The crystallinity of ZnO matrix is improved by increasing substrate temperature. • High MR values and tunable MR field sensitivity can be achieved simultaneously. [ABSTRACT FROM AUTHOR]

• Constraint tensile stress increased the α-Fe transformation start temperature of HAZs. • Constraint tensile stress increased the volume fraction and average size of Cu-rich particles in HAZs. • The increment of α-Fe transformation start temperature promoted the precipitation of Cu-rich particles in α-Fe matrix. • The tensile strength of FGHAZ increased from 970 MPa to 1032 MPa due to the nanoscale Cu-rich precipitation strengthening. The effect of welding constraint on nanoscale Cu-rich precipitation in welding heat affected zones (HAZs) of Cu-bearing steel was studied in this work. Due to the constraint tensile stress of 150 MPa, α-Fe transformation start temperature (T s) of CGHAZ and FGHAZ increased by 55 °C and 42 °C, respectively. The volume fraction and average size of 9R-structural Cu-rich particles in FGHAZ increased from 0.3 % to 0.8 % and from 5 nm to 8 nm, respectively. Three-dimensional phase field simulation shows that the increment of T s promoted the precipitation of Cu-rich particles in α-Fe matrix. However, the T s of restrained CGHAZ was too low to favor the precipitation of Cu-rich particles. The tensile strength of FGHAZ increased from 970 MPa to 1032 MPa due to the nanoscale Cu-rich precipitation strengthening. [ABSTRACT FROM AUTHOR]

Co-Diamond Like Carbon (Co-DLC) nanocomposite film is considered as a potential biosensor material owing to its various properties such as corrosion resistance and superparamagnetic property. In this work, by adjusting the substrate temperature from 298 to 673 K, the microstructure of Co-DLC nanocomposite film is modulated. With the rising of the substrate temperature, Co particle size increases from 3.8 to 6.4 nm and the crystallinity is improved; the sp2/sp3 ratio of the film is increased, which reduces micropores for penetration of corrosive entities. As a result, the saturation magnetization of superparamagnetic property is enhanced by 2.4 times from 0.11 to 0.26 T, and the total corrosion resistance of the film is enhanced by more than 300 times from 3.5 × 104 to 1.1 × 107 Ω·cm2. By establishing the mechanism model, the improvement of magnetic properties and corrosion resistance caused by microstructure controlling in Co-DLC nanocomposite film is reasonably explained. [Display omitted] • Large Co particle size and high crystallinity induced by high substrate temperature • Reduced micropores for corrosive entities penetration by increased sp2 clusters • 2.4-time superparamagnetic magnetization and 300-time corrosion resistance realized • High magnetic properties and corrosion resistance achieved simultaneously [ABSTRACT FROM AUTHOR]

The correlation between microstructure evolution, texture development and hot deformation behavior of high manganese steel for LNG were investigated through uniaxial hot tensile tests at different temperatures (800, 850, 900 and 980 °C). Hot tensile tests were carried out on a Gleeble 3800 thermomechanical simulator with a strain rate of 10 /s. Texture analysis was conducted by the orientation distribution functions acquired from the electron backscatter diffraction (EBSD). Detailed microstructure and dynamic recrystallization (DRX) were indicated by the grain orientation spread of EBSD and transmission electron microscopy (TEM). The results show that there are only two stages in the work hardening rate when the deformed microstructure is non-recrystallized or mostly recrystallized. The work hardening rate exhibits a wave-like fluctuation when the tensile temperature is near the critical DRX temperature, due to the continuous competition between the dislocation packing caused by deformation and the softening intrigued by DRX. The deformed microstructure contains the highly dense dislocation wall (HDDW) structure and the cell block structure, and the HDDW structure mostly occurs in the 〈001〉//td fiber while the latter corresponds to the 〈111〉//td fiber. What's more, <001>//td fiber has stronger orientation gradient and work hardening rate than <111>//td fiber. DRX preferentially nucleated on the <001>//td fiber through two nucleation methods: strain-induced grain boundary migration and twining nucleation. DRX grains only retain the weak {111} 〈112〉 F and {110} <112> A textures, and the overall texture was weakened and randomized. • The highly dense dislocation wall occurs in the <001>//td fiber while the cell block corresponds to the <111>//td fiber • <001>//td fiber has stronger orientation gradient and work hardening rate than <111>//td fiber • DRX preferentially nucleated on the <001>//td fiber through strain-induced grain boundary migration and twining nucleation • The work hardening curve has a fluctuating characteristic near the critical recrystallization temperature [ABSTRACT FROM AUTHOR]

Nickel alloy 690 (Ni690) were fabricated by wire arc additive manufacturing (WAAM) with three kinds of TiC particles adding contents (no TiC addition, 0.5 wt% TiC, 1.0 wt% TiC) based on cold metal transfer (CMT) technology. The effects of TiC particles adding content on the microstructure, mechanical properties and corrosion resistance were investigated. After adding 1.0 wt% TiC particles, the average length of the γ grains decreased from 301 ± 61 µm to 114 ± 15 µm and the structure of grains changed from columnar dendrite into equiaxed dendritic at the top of each layer, which is results of the heterogeneous nucleation and increase of constitutional supercooling caused by TiC particles. The difference between horizontal and vertical mechanical properties of WAAM Ni690 component disappeared because the heterogeneous nucleation caused by TiC particles prevented the epitaxial growth. The ultimate tensile strength of the WAAM 1.0TiC-Ni690 component reached 590 MPa in both directions, which increased 10 % compared with no TiC addition. The improvement of mechanical properties was owing to the grain refinement and the formation of reinforcing TiC/(Ti, Nb)C second-phase particles. The potentiodynamic polarization tests showed that the improved corrosion resistance with the increased content of TiC particles. The electrochemical impedance spectroscopy (EIS) tests results showed that due to the refined γ columnar grains providing more nucleation sites, a denser and thicker passive film was formed, which improved the corrosion resistance. The composition of the passive film was analyzed by X-ray photoelectron spectroscopy (XPS). The results reflected the more content of oxides and hydroxides of Cr in the passive film of WAAM 1.0TiC-Ni690 sample represented the denser passive film and better corrosion resistance. • Nickel alloy 690 (Ni690) were fabricated by wire arc additive manufacturing (WAAM) with different kinds of TiC particles adding contents. The TiC particles improved the mechanical properties and corrosion resistance • With the addition of TiC particles, the anisotropy in strength of WAAM Ni690 component disappeared for heterogeneous nucleation and the reinforcing TiC/(Ti, Nb)C particles improved the strength of WAAM 1.0TiC-Ni690 component in both directions reaching 590 MPa. • The refiner columnar γ grains offered more nucleation sites on the grain boundaries for the formation of thicker passive film. The more content of oxides and hydroxides of Cr in the passive film of WAAM 1.0TiC-Ni690 component represented the denser passive film and better corrosion resistance. [ABSTRACT FROM AUTHOR]

In this work, the effect of heat treatment on microstructure and mechanical properties, as well as corrosion and erosion–corrosion behavior of a nickel–aluminum bronze (NAB) alloy in sodium chloride solution was studied. The heat treatment affects remarkably the microstructure of the NAB alloy and its mechanical properties. The strength and hardness increase with the increasing content of hard phases in the alloy. There is no obvious effect of the microstructure on electrochemical corrosion behavior of the alloy under various heat treatments. However, its erosion–corrosion resistance can be improved by generation of hard phases such as β ′ and κ phases by heat treatments. [ABSTRACT FROM AUTHOR]

Co–MgO metal-insulator nanocomposite films have attracted increasing interest for their high resistivity and negative magnetoresistance at room temperature. In this study, nonuniform-microstructure Co–MgO nanocomposite films were produced, in which superparamagnetic particles and ferromagnetic clusters coexist. At the Co content of 36 at.%, the film exhibits a high room-temperature negative magnetoresistance value of over 2.2%, and a high resistivity of 7.0 × 104 μΩ m. When Co content increases, the size and quantity of Co clusters gradually increase, which causes the peaks shifting of magnetoresistance field sensitivity to higher field. Moreover, we have established a mechanism mode to explain this phenomenon, by inducing the localized magnetization flux effect and inhomogeneous current paths effect. The high-resistivity nonuniform-microstructure Co–MgO nanocomposites are realized, which can be used in different application scenarios by modulating magnetoresistance field sensitivity. • Nonuniform Co–MgO nanocomposite films show the coexistence of ferromagnetic clusters and superparamagnetic particles. • The film with 36 at.% Co content shows a large RT negative MR of 2.2% and a high resistivity of 7 × 104 μΩ m. • Significant modulation of MR field sensitivity is obtained by microstructure controlling. [ABSTRACT FROM AUTHOR]

Highlights: [•] Effect of heating rates on ferrite recrystallization was investigated. [•] Effect of heating rates on austenite formation was demonstrated. [•] Interaction between the two stages was analysed. [•] Various microstructures were obtained by different heating rates. [ABSTRACT FROM AUTHOR]

Highlights: [•] SiC particles were coated with α-Al2O3 by sol–gel technology. [•] The Ni/CSp composite was fabricated by electrodeposition. [•] The yield strength of Ni/CSp was increased by more than six times of pure Ni at 600°C. [•] SiC enhanced strength by inhibiting grain growth and interacting with dislocations. [•] Cracking of coated particles demonstrated the result of load transfer strengthening. [ABSTRACT FROM AUTHOR]

Abstract: Graphene/nickel composites were prepared by electrodeposition in a nickel sulfamate solution with graphene oxide (GO) sheets in suspension. Raman spectra demonstrated that the GO sheets had been reduced during the electrodeposition process and the graphene content was 0.12wt%. X-ray diffraction patterns showed the preferred orientation of nickel growth changing from (200) to (111) in the composites. Transmission and scanning electron microscopy images were used to help explain how the introduction of graphene substrates leads to the change of preferred orientation. Measurements showed the thermal conductivity of the composites to be about 15% more than that of pure nickel electrodeposits. Significant improvement was also demonstrated in the hardness measured by nanoindentation. [Copyright &y& Elsevier]

Abstract: A multilayer Mg–Al intermetallic coating was fabricated on the Mg alloy in molten salts at 400°C with treatment time range from 2 to 8h. The coating consists of a single Al12Mg17 intermetallic layer or Al12Mg17, Al0.58Mg0.42 and Al3Mg2 intermetallic layers. The corrosion resistance of the coating which is obtained at 400°C for 2h is the best. When the treatment time is higher than 2h, some cracks developed in the layers. The cracks were resulted from the thermal stress due to the different thermal expansion coefficient of the substrate and the intermetallic layer during the rapid cooling process. [Copyright &y& Elsevier]

Abstract: Ti-based brazing alloys were prepared by the non-consumable arc-melting technology. The wettability behavior of the brazing alloys on silicon carbide (SiC) was investigated by means of sessile drop method in vacuum at 1400°C for 10min. The brazing alloys of 91.5Ti–8.5Si (wt.%), 87.1Ti–8.1Si–4.8Cu (wt.%) and 83.2Ti–7.7Si–9.1Cu (wt.%) exhibit good wettability on SiC plate, but bad cohesion with SiC after cooling. However, the brazing alloys of 22Ti–78Si (wt.%) and 21Ti–74.2Si–4.8Cu (wt.%) exhibit both good wettability and cohesion with SiC after cooling. Microstructure, phase composition of the brazing alloys and the interface between the brazing alloys and SiC were investigated by using SEM coupled with EDS and XRD, respectively. [Copyright &y& Elsevier]

Various strategies have been developed to fabricate mechanical robust superhydrophobic membranes on the original substrates. However, for superhydrophobic coatings that have to be homologous to the inherently fragile substrate, their mechanical stability problems have not been satisfactorily solved. Herein, we prepared three hierarchical superhydrophobic Cu coating via facile pulse electrodeposition with microstructure size of 10–15, 30–40, and 60–70 µm, respectively. The resulting superhydrophobic coatings simultaneously exhibit excellent self-cleaning, mechanical robustness, and corrosion resistance. A hydrophobic mechanism suitable for worn superhydrophobic surfaces was proposed, which can well analyze the influence of microstructure changes on wettability. Moreover, these three coatings can withstand 15, 50, and 100 cycles of sandpaper abrasion, respectively, as the size of the microstructure increases. The results demonstrate a size effect of microstructure, which means surfaces with larger-sized microstructures can better maintain their superhydrophobicity under mechanical damage. Our findings offer a reference for improving the mechanical robustness of other superhydrophobic coatings that are homologous to the substrate. [Display omitted] • Three superhydrophobic Cu coatings with mechanical robustness, self-cleaning, and corrosion resistance were fabricated. • A hydrophobic mechanism suitable for worn superhydrophobic surfaces was proposed. • The size effect of microstructure on resisting mechanical damage was investigated. • A strategy in improving the mechanical stability of fragile coatings homologous to the substrate was found. [ABSTRACT FROM AUTHOR]

Abstract: 22Ti–78Si(wt.%) eutectic braze was prepared through the non-consumable arc-melting technology. Wetting behavior of the braze on silicon carbide (SiC) was investigated by means of sessile drop method in vacuum at 1400 °C for 10 min. The result indicates that the braze exhibits good wettability (contact angle 25°) and adhesion with SiC. Main reasons are that TiC which owns higher surface energy is formed on SiC surface and the braze has an appropriate coefficient of thermal expansion (CTE) to that of SiC. [Copyright &y& Elsevier]

Abstract: In this paper, a new method to prepare Al–8.5Fe–1.3V–1.7Si (FVS0812) alloy by spray co-deposition with added its over-sprayed powders was studied. Two kinds of powders which are different in particle size (≤43, 43–74μm) were used in the new process. Under the same experimental conditions, the alloys were produced by spray deposition without powders and the spray co-deposition. The deposited alloys were subsequently hot extruded with an extrusion ratio of 16:1 at 450°C. The results showed that the addition of over-sprayed powders refined the microstructure and improved the mechanical properties, and the effect of the fine over-sprayed powders was more evident than that of the coarse powders. The ultimate tensile strength was enhanced from 360.5MPa (without powders) to 433.3MPa (≤43μm) and 392.4MPa (43–74μm). The mechanical properties increase is mainly due to the over-sprayed powders pulverizing melt effectively, absorbing heat greatly and increasing the number of heterogeneous nuclei in matrix, which result in the enhancement of cooling rate and the refinement of microstructure. [Copyright &y& Elsevier]

Abstract: The composite electroforming technology was propounded to fabricate nano-sized carbide silicon particles (nano-SiC) reinforced copper composite. The surface morphology, microstructure, microhardness, wear resistance and electrical resistivity (E r) were examined. The results showed that nano-SiC were embedded in copper matrix uniformly and tightly. Comparing with the pure copper deposit, the surface of the composite was more fine, more compact and smooth, and the composite exhibited higher microhardness and better wear resistance. Besides, the change range of E r was small. [Copyright &y& Elsevier]

Abstract: The silicon carbide particles (SiCp) dispersion-strengthened copper matrix composites (Cu/SiCp) were fabricated by composite electroforming technology. The microstructure, tensile property and wear behavior of Cu/SiCp composites were investigated. The results showed that composites with different SiCp contents were obtained. The microstructure of the composite presented a uniform distribution of SiCp in the matrix and good interfacial integrity. The hardness, yield strength and rigidity of the composites increased with increasing SiCp content, but at the cost of ductility. Increasing SiCp content in the composite was not always beneficial to the ultimate tensile strength and wear resistance. The ultimate tensile strength increased with SiCp content increasing up to 16 vol.% and decreased as exceeding 16 vol.%, and the wear mass loss decreased with SiCp content increasing up to 21 vol.% and increased again as exceeding 21 vol.%. [Copyright &y& Elsevier]

Abstract: Electrodeposited nickel was prepared from a sulphamate bath at different current densities ranging from 0.01 A cm−2 to 0.1 A cm−2. Based on the analysis of the microstructure, the corrosion behavior of the electrodeposited nickel in 3.5%NaCl solution was studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). All the electrodeposits display active–passive–transpassive behavior in potentiodynamic polarization process. The electrodeposits with the best corrosion resistance are obtained at 0.05 A cm−2. As for other electrodeposits, the corrosion potential and breakdown potential decrease with increasing current density used to prepare electrodeposits. However, the variation of both corrosion current density and passive current density is opposite to that of the corrosion potential. The changes in the charge-transfer resistance determined from the impedance spectra are consistent with the results determined from potentiodynamic measurements. [Copyright &y& Elsevier]

To realize the potential application of the Co-DLC magnetic nanocomposite film in biosensor, it is necessary to obtain superparamagnetic property with high magnetization and good corrosion resistance in Co-DLC film. However, the cobalt carbide produced in the traditional preparation process will deteriorate the superparamagnetic property of Co-DLC film. To suppress the formation of cobalt carbide, strong magnetic target co-sputtering has been induced to prepare the Co-DLC nanocomposite films in this work. The results show that the cobalt particles are distributed in the amorphous DLC matrix. Most of cobalt exists in the form of metallic cobalt, and no cobalt carbide is formed during the film deposition process. The films maintain superparamagnetic property, which fits well with the Langevin equation. The saturation magnetization of the Co-DLC films increases with the increase of cobalt content, which reaches 0.068 T at cobalt content of 36 at. %. Meanwhile, when the cobalt content increases, the degree of graphitization of the film increases, which leads to a decrease in corrosion resistance of the film. Whereas, the polarization resistance of Co-DLC nanocomposite film is still higher than 1.03 × 105 Ω·cm2. The Co-DLC nanocomposite films with cobalt content between 29 and 36 at. % exhibit superparamagnetic property with high saturation magnetization and corrosion resistance. [Display omitted] • The method of strong magnetic target co-sputtering inhibits the formation of cobalt carbides in Co-DLC films successfully. • These films maintain superparamagnetic property, which is fitted well with Langevin equation. • The corrosion resistance of the Co-DLC film is above 10 times higher than that of the cobalt film. • The films with cobalt content between 29 and 36 at. % exhibit both high saturation magnetization and corrosion resistance. [ABSTRACT FROM AUTHOR]

A supersaturated solid solution layer with a fine-grained size of 30–50 μm was formed on a nickel–aluminum bronze via laser surface quenching technology, and its corrosion resistance was improved by 42.6%, which was attributed to the homogenized element distribution and the formation of a more protective film during corrosion process. • The microstructure of as-cast NiAl bronze was refined by laser surface quenching. • Selective phase corrosion was eliminated for the uniform element redistribution. • Corrosion rate decreased 42.6% after laser surface quenching. • Enhanced corrosion resistance was ascribed to formation of a more protective film. Laser surface quenching technology was utilized to modify the surface microstructure of as-cast nickel-aluminum bronze. A supersaturated solid solution layer with a fine-grained size of 30–50 μm was formed, and its corrosion behavior was studied by electrochemical measurements and long-term immersion corrosion test. It was found that laser surface quenching homogenized the distribution of elements in the constituent phases and eliminated the selective phase corrosion. Due to the formation of a more protective film on laser quenched NAB alloy, the corrosion rate reduced about 42.6% compared with that of as-cast NAB alloy. [ABSTRACT FROM AUTHOR]