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In this article, the microstructure and mechanical properties of the Fe–0.31C–6.86Mn–3.53Al steel and DP980 and 22MnB5 steel dissimilar/similar joints by fiber laser welding are studied. Based on experimental results, fusion zone (FZ) of transformation‐induced plasticity (TRIP)‐welded joint mainly consists of 77 vol% martensite and 23 vol% ferrite. The FZ of TRIP‐DP980 and TRIP‐22MnB5 welds mainly consist of martensite. The hardness profile of weld cross‐section exhibits significant asymmetry, and softening zones hardness of TRIP‐DP980 and TRIP‐22MnB5 accounts for 82% and 64% of DP980 and 22MnB5 base materials (BM), respectively. However, no softening zone is observed on TRIP steel side, primarily due to the lack of martensite in TRIP BM. The tensile results showed that welding efficiency of TRIP‐TRIP reached 99%, but elongation of welded specimen is only 50% of TRIP BM due to the high hardness and brittleness of FZ region. TRIP‐DP980 and TRIP‐22MnB5 joints did not fail in softening zone, because the constraint stress is generated on both sides of softening zone to inhibit the plastic deformation in softening zone during tensile process. The tensile stress is distributed on the surface of tensile specimens and concentrated in BM on the side with low yield strength (YS), resulting in the final fracture. [ABSTRACT FROM AUTHOR]

The flattening behavior of in-flight particles during plasma spraying is a highly intricate process affected by numerous factors. Therefore, in this work, in-flight particles (spherical NiCrBSi powder) were collected with the water quenching process, and the morphology and composition differences between the original powder particles and the melted in-flight particles were observed using scanning electron microscopy (SEM). The particle size in various states was recorded and calculated. The internal structure of the particles was analyzed to elucidate their morphology and compositions under different flow rates of primary gas (FRPG). A coating with 1.25% porosity and a hardness of 767 HV0.5 was achieved at the FRPG of 80 L/min. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to characterize the microstructures of the obtained coatings. It was found that the as-sprayed coating had a certain amount of the amorphous phase. A noteworthy correlation was also established, wherein a decreased distance from the substrate, augmented spraying passes, and reduced amorphous phase content were interrelated. Concurrently, a noticeable influence of the tamping effect exerted by the in-flight particles on the coating was observed. [ABSTRACT FROM AUTHOR]

Due to the large output of construction waste soils, it has become an enormous challenge for human society and the ecological environment. The purpose of this paper is to discuss the possibility of using a stabilized waste soil in road engineering. Cement and polymer stabilizers were added to the waste soil, and the effect of the stabilizer on the strength and water stability of the stabilized soil was studied. The structure and morphology of the specimens were analyzed using an X-ray diffractometer (XRD) and a scanning electron microscope (SEM). The results show that the unconfined compressive strength increases by 25.0% and the 28-day water stability coefficient, K increases by 59.6% after the addition of the stabilizer. The XRD curve shows that the addition of the new stabilizer does not produce a new characteristic peak, but the diffraction peak strength of some minerals can be improved. SEM shows that the surface of stabilized soil particles is covered by materials, and the particles show obvious agglomeration, forming a network structure, which improves the strength and water stability of the soil. [ABSTRACT FROM AUTHOR]

Direct attainment of the crystal state corresponding to desired performances in processing can improve the productivity of semi‐crystalline polymer products. This work tried to propose the idea to approach the target by exploring the effects of nucleating agent content on non‐isothermal crystallization kinetics, isothermally crystallization morphologies and macroscopic properties of polypropylene (PP). The nucleating agent content varied from 0 to 0.5 phr, and all samples were prepared by melting blending at 180°C as the antioxidant and lubricant ensured fine stability and processing. The differential scanning calorimetry results and non‐isothermal crystallization kinetics indicated that introducing 0.3 phr nucleating agent advanced both initial crystallization and melting about 10°C and improved crystallization rate and crystallinity. Besides, 145°C was determined as an isothermal crystallization condition by setting temperature gradient, and the crystallization kinetics were described by a power‐law equation well. The average crystal size was refined to 40 μm uniformly and crystallization time was reduced to 1.5 min as loading 0.5 phr nucleating agent, contributing to the significant improvements in tensile and physical properties. Thus, adding such a short‐time heat insulation procedure into the non‐isothermal cooling stage during processing can obtain desired crystal state directly with loading adequate nucleating agent. [ABSTRACT FROM AUTHOR]

The distribution of the dendrite arrays and the primary dendrite arm spacing (PDAS) in large-sized single-crystal superalloy blade was investigated by Voronoi tessellation. The dendrite arrays were hexagonal at the airfoil center and random at the trailing edge. The PDAS was gradually increased from the leading edge (about 370 μm) to the trailing edge (about 500 μm). With the solidification distance increasing, the PDAS in large-sized blade was decreased (about 380 μm) at the middle blade. [ABSTRACT FROM AUTHOR]

The accumulation of pollutants on the surface of a Concentrating Solar Power (CSP) station reduces the power generation efficiency of the whole power plant, affects electricity output, and decreases sales income; therefore, it is particularly important to develop a reasonable and effective cleaning process. Surface pollutants which have a strong interaction with the cleaning process of power stations can determine the quality of cleaning to a certain extent. In this paper, the pollutants on the surface of a trough CSP station with different usage times were collected and characterized using a scanning electron microscope (SEM), a particle size analyzer (PSA), and a transmission electron microscope (TEM). It was found that most of the surface pollutants were of a fine size and included amorphous particles which mainly resulted from the sedimentation of particles suspended for a short time or particles in the process of atmospheric circulation for a long time. Considering the service life of the mirror and the scarcity of water resources in the area where the trough CSP power station is located, a brush-based dry cleaning process with different cleaning times was developed. By comparing the changes in the reflectivity and micro-morphology of the mirror surface before and after cleaning, the feasibility and superiority of the brush-based dry cleaning process were fully confirmed. [ABSTRACT FROM AUTHOR]

Cermet coatings are post-treated by a new surface microcrystallization technology, namely high-temperature-assisted ultrasonic deep rolling (HT + UDR). The process parameters of ultrasonic deep rolling significantly affect the microstructure and tribological properties of the Ni-WC coatings. In this paper, the samples were treated with different preloading depths (0.20 mm, 0.25 mm, and 0.30 mm), and the microstructure and properties of the coatings were characterized by SEM, EDS, X-ray stress analysis, and micro-Vickers hardness testing. An MMW-1A-type friction and wear tester was used for the dry friction and wear test at room temperature, respectively. Compared with the untreated sample, plastic rheology occurred on the surface of the coatings after HT + UDR, showing a phenomenon of "cutting peaks and filling valleys". In the treated coatings, visible cracks were eliminated, and the inside of the coating was denser. The surface hard phase was increased as a "skeleton" and embedded with the soft phase, which played a role in strong and tough bonding. After HT + UDR + 0.25 mm treatment, the surface roughness increased by 68%, the microhardness of the surface layer reached a maximum of 726.3 HV0.1, and the residual tensile stress changed from 165.5 MPa to −337.9 MPa, which inhibited the germination and propagation of cracks. HT + UDR improved the wear resistance of the coating in many aspects. The coating after the 0.25 mm preloading depth treatment possessed the smallest friction coefficient and the lowest wear amount, which is 0.04 and 4.5 mg, respectively. The wear form was abrasive wear, and the comprehensive tribological performance is the best. [ABSTRACT FROM AUTHOR]

In this study, we investigate the effect of the exposure dose on the mechanical property of the photoresins generated with acrylate self-polymerization and thiol-ene polymerization. The results indicate that the mechanical performance of the thiol-ene photoresin is highly depended on the exposure dose during the solidification process. With 350-fold exposure dose change, the stiffness of the thiol-ene photoresin reached more that 700-fold change compare to 14-fold of the acrylate photoresin. We developed a TPL photoresist based on our results and show the capability to fabricate microstrucutres with high resolution and variable mechanical performances using this method. [ABSTRACT FROM AUTHOR]

Inertial microfluidics functions solely based on the fluid dynamics at relatively high flow speed. Thus, channel geometry is the critical design parameter that contributes to the performance of the device. Four basic channel geometries (i.e., straight, expansion-contraction, spiral and serpentine) have been proposed and extensively studied. To further enhance the performance, innovative channel design through combining two or more geometries is promising. This work explores embedding periodic concave and convex obstacle microstructures in sinusoidal channels and investigates their influence on particle inertial focusing and separation. The concave obstacles could significantly enhance the Dean flow and tune the flow range for particle inertial focusing and separation. Based on this finding, we propose a cascaded device by connecting two sinusoidal channels consecutively for rare cell separation. The concave obstacles are embedded in the second channel to adapt its operational flow rates and enable the functional operation of both channels. Polystyrene beads and breast cancer cells (T47D) spiking in the blood were respectively processed by the proposed device. The results indicate an outstanding separation performance, with 3 to 4 orders of magnitude enhancement in purity for samples with a primary cancer cells ratio of 0.01% and 0.001%, respectively. Embedding microstructures as obstacles brings more flexibility to the design of inertial microfluidic devices, offering a feasible new way to combine two or more serial processing units for high-performance separation. [ABSTRACT FROM AUTHOR]

To obtain the growth and age characteristics of Diaphus brachycephalus in the South China Sea (SCS), specimens of D. brachycephalus were collected by a mid-water trawl in January and June 2015. The relationship between standard length (L) and body weight (W) was W = 0.00002699L2.8789, with no significant differences between the two survey stations and the sexes. Microscopic observation of the sagittal otoliths revealed that the daily growth increments in each period were divided into the central zone, middle zone, and external zone. The age was determined by summing the daily growth increments of the three areas. The von Bertalanffy growth curve fitted to the relationship between age and L was shown as: L = 65.6[1 − exp{−0.0132(t − 6.94)}], r2 = 0.935. The growth rate decreased from juvenile to adult, with a maximum rate of 0.436 mm day−1. The back-calculated hatching dates of specimens were speculated to be from March to November, but predominantly occurred from April to May and from September to October. [ABSTRACT FROM AUTHOR]

A wire arc additive manufacturing system, based on cold metal transfer technology, was utilized to manufacture the Al-Mg alloy walls. ER5556 wire was used as the filler metal to deposit Al-Mg alloys layer by layer. Based on the orthogonal experiments, the process parameters of the welding current, welding speed and gas flow, as well as interlayer residence time, were adjusted to investigate the microstructure, phase composition and crystal orientation as well as material properties of Al-Mg alloyed additive. The results show that the grain size of Al-Mg alloyed additive becomes smaller with the decrease of welding current or increased welding speed. It is easier to obtain the additive parts with better grain uniformity with the increase of gas flow or interlayer residence time. The phase composition of Al-Mg alloyed additive consists of α-Al matrix and γ (Al12Mg17) phase. The eutectic reaction occurs during the additive manufacturing process, and the liquefying film is formed on the α-Al matrix and coated on the γ phase surface. The crystal grows preferentially along the <111> and <101> orientations. When the welding current is 90 A, the welding speed is 700 mm/min, the gas flow is 22.5 L/min and the interlayer residence time is 5 min, the Al-Mg alloy additive obtains the highest tensile strength. Under the optimal process parameters, the average grain size of Al-Mg alloyed additive is 25 μm, the transverse tensile strength reaches 382 MPa, the impact absorption energy is 26 J, and the corrosion current density is 3.485 × 10−6 A·cm−2. Both tensile and impact fracture modes of Al-Mg alloyed additive are ductile fractures. From the current view, the Al-Mg alloys manufactured by WAAM-CMT have a better performance than those produced by the traditional casting process. [ABSTRACT FROM AUTHOR]

A novel island-like MoO3-x film is directly fabricated on Mo foil by a simple preoxidation-hydrothermal process. The MoO3-x islands are firmly fixed on Mo substrate, while separated and surrounded by ditch-like cracks. The as-synthesized MoO3-x@Mo can be directly used as binder-free anode for a bendable Li ion battery. The uniform island-like structure provides MoO3-x both the excellent mechanical/electrical connection with Mo current collector and significantly improved Li ion diffusion ability, inducing the considerably low internal cell resistance and high rate performance. The MoO3-x@Mo electrode delivers a high areal capacity of 0.77 mAh/cm2 at 0.4 mA/cm2, and after cycling at 0.5 mA/cm2 for 125 cycles, the areal capacity can maintain at 0.47 mAh/cm2 with a retention ratio of 99.89%. Furthermore, the presence of network cracks in MoO3-x layer endues the MoO3-x@Mo electrode with excellent flexibility, the fabricated batteries could work normally in different bending state. This novel island-like microstructure suggests a new possibility to prepare flexible electrode with excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

Previous studies have shown that structure has a significant influence on the mechanical deformation of unsaturated loess, but there is little published information focused on the influence mechanism of microstructure and mesostructure on the mechanical properties of loess. In this paper, the unsaturated undisturbed loess and its remolded loess under the same physical condition were taken as the research objects. The unsaturated triaxial shear tests with constant suction and net confining pressure were carried out, and the microstructure differences between the two are compared by using SEM and CT scanning to reveal the influence of structure on strength characteristics. The test results show that the cohesion and internal friction angle of undisturbed loess are greater than those of remolded loess. The angle of undisturbed soil particles is obvious, and the particles are bracket contact with good cementation. The remolded loess particles are close to round shape, and the particles are inlaid contact with destroyed cementation. The average radius of undisturbed soil is higher than that of remolded soil, indicating that there are bracket pores in undisturbed soil, but the bracket structure and macropores are deformed during shear deformation, and good structural and cementation ensure the strength of loess specimens. [ABSTRACT FROM AUTHOR]

Age and growth of a dominant lanternfish Ceratoscopelus warmingii in the South China Sea were investigated based on sagittal otolith microstructure of juvenile and adult specimens collected in June 2015. The length–weight (L-W) relationship for C. warmingii was Wf= 0.00000814 L3.1170 (females) and Wm= 0.00001071 L3.3043 (males), revealing both positive allometric growth and non-significant difference between the sexes. Three distinct zones of the otolith microstructure were depicted, a central zone (CZ), middle zone (MZ) and external zone (EZ). Age was estimated by summing the daily growth increments in otolith sections on the assumption of daily deposition. The von Bertalanffy models of females and males were fitted as Lf = 75.9 [1−exp{−0.0074 (t−14.1)}] and Lm = 65.0[1−exp{−0.0097 (t−7.6)}], respectively. The maximum growth rates estimated were 0.319 mm day−1 for females and 0.345 mm day−1 for males, and thereafter the growth rate decreased with age. The back-calculated hatching date of specimens collected was determined as from August of last year to March of next year with a peak in winter. Theoretical maximum growth of C. warmingii appeared to occur near the metamorphic period. [ABSTRACT FROM AUTHOR]

The main hydration products of calcium sulfoaluminate (CSA) cement were analyzed by X-ray diffraction and thermogravimetry. The pore characteristics of CSA cement paste with the incorporation of different supplementary cementitious materials (SCMs) were studied by a mercury intrusion porosimeter. Water-to-binder ratios between 0.24 and 0.73 were used in the mixtures. The microstructure of the CSA cement concrete was observed by backscattering electron microscopy. The test results indicate that compared with ordinary Portland cement (OPC) paste, CSA cement paste has a coarser pore volume. Silica fume can substantially reduce the median pore diameter (MPD) of CSA cement paste. With the action of SCMs and the adjustment of the water to binder ratio, the pore structure of the CSA cement paste is significantly refined, harmful pores and air pores are greatly reduced. SCMs can play a substantial filling role in CSA cement concrete, which can optimize the pore structure and improve the related properties. [Display omitted] • Compared with OPC paste, CSA cement paste has a coarser pore volume. • Silica fume can significantly reduce the median pore diameter of CSA cement paste. • With the action of SCM, pore structure of CSA cement paste is remarkably refined. [ABSTRACT FROM AUTHOR]

Alloy design of Cr-Co-Ni-Ta eutectic medium entropy alloys (EMEAs) was performed through a CALPHAD method coupled with experimental study, with the aim to attain high phase stability as well as excellent mechanical properties. Based on calculated pseudo-binary diagram, CrCoNiTax (x = 0.1, 0.3, 0.4, 0.5, 0.7) medium entropy alloys were investigated. Two phases, FCC solid solution and Laves phase, were identified in the alloys. With increasing Ta content, the volume fraction of hard and brittle Laves phase increased, microstructure changed from hypoeutectic (Ta0.1, Ta0.3) to eutectic (Ta0.4) and then to hypereutectic (Ta0.5, Ta0.7). The stability of phases was assessed by considering the thermodynamic parameter Ω and valence electron concentration (VEC). The eutectic phases become stable when 1.42 < Ω < 0.74 and 7.5 < VEC < 8.25. In addition, based on nanoindentation, the results indicated that solid solution strengthening in γ phase was significantly enhanced, eutectic phase in CrCoNiTa0.4 EMEA was found to process the highest microhardness and elastic modulus. Finally, the hardness of alloys was positively correlated with the content of Ta and the plastic strain of alloys obviously decreased, while the compression strength firstly increased and then decreased. CrCoNiTa0.4 was the most promising alloy with the highest compression strength (2502 MPa) and high plastic strain (20.6%). [ABSTRACT FROM AUTHOR]

Mechanoluminescent (ML) materials featuring renewable mechanical‐to‐optical conversion have shown promising prospects in stress sensing, lighting, and display. However, the advancement in ML applications is being restrained by the obstacles in developing efficient ML materials and understanding the underlying ML mechanisms. Herein, a matrix evolution strategy to modulate the local microstructure and electronic environment around the luminescent activators is proposed, which not only supports the batch development of new ML materials but also provides a well‐connected platform for systematically revealing the mechanism of achieving efficient ML performance. The feasibility of the strategy is proved by constructing and evaluating a series of ML materials with matrix‐dependent luminescent properties in experimental‐theoretical collaboration. It is demonstrated that the construction of piezoluminescence is available in both non‐centrosymmetric and centrosymmetric matrices without being restricted by lattice symmetry. The inter‐electronic‐levels and shallow electron traps formed by activator doping enhance the electron recombination efficiency through tunneling and conduction band transfer pathways. The results are expected to accelerate the exploitation of ML material systems and to deepen the comprehensive apprehending of ML mechanisms, thereby guiding the rational design and widespread use of efficient ML materials. [ABSTRACT FROM AUTHOR]

This study is aimed at exploring the effects of multi-stage homogenization and trace amounts of Zr and Sc on the microstructures, mechanical properties, and recrystallization of Al–4.5Zn–1.5Mg alloys. The mechanical properties of the AA7005 aluminum alloys after the T6 heat treatment were evaluated through a hardness test and tensile test. The microstructures were analyzed by an optical microscope (OM), a differential scanning calorimeter (DSC), a transmission electron microscope (TEM), a scanning electron microscope (SEM), and electron backscattered diffraction (EBSD). The results show that the grain refinement effect of the as-cast, homogenized, and recrystallized Al–4.5Zn–1.5Mg alloy containing 0.05Sc (wt%) after the T6 heat treatment was more significant than that of the alloy containing 0.1Zr (wt%). In addition, compared with the aforementioned one-stage homogenization heat treatment, the two-stage homogenization made the dispersed grain phase (Al3Zr/Al3Sc) smaller. As a result, the T6 mechanical strength of the alloy after the two-stage homogenization heat treatment was better than that of the contrastive alloy after the one-stage homogenization heat treatment. However, the two different homogenization heat treatments caused a greater divergence between the sizes of the dispersed grain phases of the Al–4.5Zn–1.5Mg alloys containing Zr than between the sizes of the dispersed grain phases of the alloys containing Sc. Therefore, after the two-stage homogenization heat treatment, the alloy with 0.1Zr (wt%) promoted the mechanical properties better than the alloy with 0.05Sc (wt%). [ABSTRACT FROM AUTHOR]

Copper‐graphite composites prepared by spark plasma sintering (SPS) were used as raw material to synthesize copper‐graphite‐polytetrafluoroethylene (PTFE) composites via the hydrothermal impregnation of a PTFE emulsion. The microstructure, hydrophobic performance, friction property and interface behavior were systematically studied using scanning electron microscopy (SEM), a surface science comprehensive tester and a friction tester combined with various characterization methods, such as X‐ray diffraction (XRD), a laser particle size analyzer and metallographic microscopy. The results revealed that the copper‐coated graphite was consistent with the diffraction patterns of copper and graphite, and the coated‐copper had uniformly covered the graphite surface with good interface combination. The interface combination worsened with a decrease of the mass fraction of copper in the composites. Moreover, the water contact angle of the copper‐graphite‐PTFE composite of 50 wt. % Cu after PTFE impregnation reached 160°, and was hence superhydrophobic, while the copper‐graphite‐PTFE composite of 45 wt. % Cu exhibited the optimal performance with a friction coefficient, wear rate and resistivity of 0.112, 3.25×10−3 mm3/(N m), and 12×10−7 Ω m, respectively. PTFE impregnation improved the hydrophobicity and friction‐and‐wear properties of the copper‐graphite composites, and the resulting conductivity could meet the requirements of practical applications. Our results indicated that the content of copper played a crucial part in determining the comprehensive property of copper‐graphite‐PTFE composites. [ABSTRACT FROM AUTHOR]

Recently, various kinds of methods have been implemented to broaden the visible light response and fasten the carrier's separation of TiO2‐based photoanodes. As a promising hydrogen evolution reaction catalyst, MoSe2 is rarely investigated especially combined with TiO2 photoanode. In this study, we report a composite photoanode of MoSe2 nanosheets (with 1T and 2H phase)‐modified 3D TiO2 nanoflowers (NFs).The hybrid of 3D TiO2 NFs/2D MoSe2 holds great promise in boosting the PEC water splitting performance. TiO2 NFs/MoSe2‐15 showed the largest photocurrent density of 1.40 mA/cm2, which was five times higher than that of pure TiO2 NFs under AM1.5G illumination. Moreover 10 times improvement in current density was observed for the TiO2 NFs/MoSe2‐15 under visible light. This increase could be ascribed to synergistic effects of light absorption enhancement and more efficient carrier separation after MoSe2 modification. This study not only provides a reference to boost the photoelectrochemical performance of photoelectrodes but also renders a perspective on the potential applications of MoSe2 nanosheets. [ABSTRACT FROM AUTHOR]