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The DC voltage level of photovoltaic and PEDF applications have continuously advanced, reaching up to DC3000V. This presents new requirements for DC circuit breakers operating at higher voltages (>DC1500V) to ensure effective fault protection in the DC side. Based on this, a self-powered hybrid DC circuit breaker with synergistic effect of step-down and divided current is proposed. This innovative design utilizes the voltage of main branch to trigger IGBT conduction, eliminating the need for an additional trigger circuit. The interruption characteristics is analyzed by simulation. The reactor and shunt resistance effectively reduce the peak currents of both main and transfer branches. This approach significantly mitigates the voltage stress on the mechanical switch, reduces the risk of post-arc reignition, and shortens the interruption time. The circuit breaker topology proposed enables the DC arc interruption at larger current and higher voltage, serving as the valuable guide for the implementation of hybrid DC circuit breakers in renewable energy power systems.

In this paper, we propose a way to partition any constacyclic code over a finite field in its equivalence classes according to the algebraic structure of the code. Such a method gives the generalization of cyclically permutable codes (CPCs), which are called constacyclically permutable codes (CCPCs), and it is useful to derive a CCPC from a given constacyclic code. Moreover, we present an enumerative formula for the code size of such a CCPC, with all of the terms being positive integers, and we provide an algebraic method to produce such a CCPC.

In the present work, cast iron was used as the carbon source to fabricate WC particle gradient-reinforced W–Cu composites. The results revealed that the surface layer of W–Cu composites after carbonization can be divided into a complete carbonization zone and core-shell structure transition zone, the thickness of the carbonized layer increased gradually with the extension of treatment time. In addition to the W phase and Cu phase, WC and Fe3W3C phases are formed in the surface layer. The hardness and compressive strength of the surface layer show a trend of first increasing and then decreasing, and the arc erosion resistance of the surface layer gradually improves with the treatment time extending. The C atoms diffusion relationship between carbonization layer thickness (D), sintering temperature (T), and treatment time (t) of W–Cu composites with cast iron can be fitted as follows: D=1.9287×1013texp(‐929231RT).

With the rapid development of the power industry and the widespread adoption of smart meters, the occurrence of smart meter failures has also become more frequent. Consequently, the classification of smart meter faults has become a crucial task to ensure quality assurance in the power industry. Accurately determining the fault types of smart meters and improving maintenance efficiency are of utmost importance to ensure their safe and stable operation. Traditional methods for classifying smart meter faults primarily rely on manual inspection and testing, which suffer from issues such as low classification efficiency, high cost, susceptibility to missed detections, and false detections. In recent years, machine learning methods have demonstrated advantages in this field. This paper proposes an ensemble learning method for the multi-classification of smart meter faults to enhance the efficiency and accuracy of fault classification. Firstly, various data preprocessing techniques are employed to clean and extract features from a real-world dataset, thereby enhancing the data quality of the smart meter fault types. Secondly, a selection process is conducted to screen classical machine learning algorithms, resulting in the choice of three algorithms: K Nearest Neighbors (KNN), Random Forest (RF), and Xtreme Gradient Boosting (XGBoost). These algorithms are then utilized to classify the fault types of smart meters. Finally, a multi-classification ensemble learning method is introduced to combine the results from multiple classifiers, thereby improving the accuracy and robustness of smart meter fault classification. Experimental results demonstrate that the proposed method exhibits high accuracy and robustness in fault classification, offering promising applications and value for widespread adoption.

The TiB2p/Cu composites were prepared by current-assisted vacuum hot pressing (CAVHP) combined with rolling using in-situ spherical TiB2p/Cu composite powder as raw material. The effects of rolling deformation on the microstructure and properties of the sintered TiB2p/Cu composite were investigated. The results show that CAVHP leads to a rapid densification of the composite powder compact, and the subsequent rolling deformation is able to eliminate the unclosed pores and achieve a uniform distribution of TiB2p. The dynamic recrystallization during cold rolling refines the Cu matrix grains to ultrafine grains with an average grain size of 0.47 μm. The cold rolled TiB2p/Cu composite obtains a remarkable comprehensive performance with ultimate tensile strength, yield strength and electrical conductivity of 621 MPa, 567 MPa and 86.3% IACS, respectively. In addition, the strengthening and fracture mechanism of the cold rolled TiB2p/Cu composite are analyzed. This work will explore a new technological solution for the preparation of high-performance Cu matrix composites.

Background: Denglao Qingguan decoction (DLQGD) has been extensively utilized for the treatment of colds, demonstrating significant therapeutic efficacy. Human Coronavirus 229E (HCoV-229E) is considered a crucial etiological agent of influenza. However, the specific impact and underlying mechanisms of DLQGD on HCoV-229E remain poorly understood. Methods: Active ingredients and targets information of DLQGD were collected from Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP), literature search, and Swiss ADEM database. The Genecard database was used to collect HCoV-229E related targets. We built an “ingredient-target network” through Cytoscape. Protein - Protein interaction (PPI) networks were mapped using the String database. The Kyoto Encyclopedia of Genes and Genomes (KEGG) and Gene Ontology (GO) were enriched using the DAVID database. Then, we used molecular docking techniques to verify the binding activity between the core compounds and the core gene targets. Finally, in vitro experiments were conducted to validate DLQGD's antiviral activity against HCoV-229E and assess its anti-inflammatory effects. Results: In total, we identified 227 active components in DLQGD. 18 key targets involved in its activity against HCoV-229E. Notably, the core active ingredients including quercetin, luteolin, kaempferol, β-sitosterol, and apigenin, and the core therapeutic targets were CXCL8, RELA, MAPK14, NFKB1, and CXCL10, all associated with HCoV-229E. KEGG enrichment results included IL-17 signaling pathway, Toll-like receptor signaling pathway, RIG-I-like receptor signaling pathway and so on. The core active ingredients and the core therapeutic targets and Human Aminopeptidase N (ANPEP) all showed good binding activity by molecular docking verification. In vitro, DLQGD exhibited anti-HCoV-229E activity and anti-inflammatory effects. Conclusion: Our study suggests that DLQGD has both effects of anti-HCoV-229E and anti-inflammatory. The core active ingredients (quercetin, luteolin, kaempferol, β-sitosterol, apigenin) and the core therapeutic targets (CXCL8, RELA, MAPK14, NFKB1, CXCL10) may play key roles in the pharmacological action of DLQGD against HCoV-229E.

In order to reduce the sintering temperature of the Mo–Cu composites, solution combustion synthesis was used to fabricate ultrafine Mo–Cu composite powders, in which Mo and Cu mixed uniformly. Firstly, solution combustion synthesis was conducted to prepared molybdenum and copper oxides composite powders. However, the residual carbon in the as-synthesized precursors requires additional calcination in nitrogen atmosphere during the reduction process to obtain pure Mo–Cu composite powders. Then the Mo–Cu composites were fabricated by liquid phase sintering at low temperatures of 1050–1180 °C using the Mo–Cu composite powders. The Mo–20Cu and Mo–30Cu composites can reach a relative density of >95% after sintering at a low temperature of 1100 °C, which may be attributed to both the small particle size of Mo and the high uniformity of Mo and Cu distribution.

Oriented SiC whisker-reinforced Al2O3/Cu composites were fabricated by powder metallurgy and hot extrusion. The microstructure of the composites was characterized by scanning electron microscopy. The mechanical properties and electrical conductivity of the composites were measured. The results indicated that the SiC whiskers aligned along the extrusion direction, and the nano Al2O3 particles were uniformly dispersed in the Cu matrix with ideal interfacial bonding. Particle and whisker hybrid reinforcement significantly enhanced the mechanical properties. The yield strength and elongation of (1 vol.%SiCw + Al2O3)/Cu composites were 6% and 15.6% higher than those of the Al2O3/Cu composites, respectively. The experimental yield strength was consistent with the theoretical value associated with different strengthening mechanisms. The main strengthening mechanisms were fine grain strengthening, Orowan strengthening and load transfer strengthening. The electrical conductivity of all the composites was higher than 82.8% IACS; however, the SiC whiskers led to electrical conductivity anisotropy. In general, the electrical conductivity of composites is related to the volume fraction and type of reinforcement. Therefore, the influence of the hybrid composition on the electrical conductivity was studied, and an analytical model for the electrical conductivity of hybrid-reinforced copper matrix composites was established, including the characteristic parameters of the particles and whiskers. The model and presented findings can provide a design basis for hybrid-reinforced composites.

Clarifying the trade-offs/synergies of ecosystem services is crucial for achieving a win-win situation in economic development and ecological conservation. Past studies have lacked research on ecosystem service functional management zones that integrate socio-economic factors and ecological conservation, particularly based on predictive scenarios. Based on the above, this study innovatively established a multi scenario simulation model and framework (EST-EMZ) for the study of ecosystem service (ES) trade-off/synergy and ecological management zoning, combining remote sensing and socio-economic data from 2000 to 2020 in the Chang-Zhu-Tan Metropolitan Area (CZTMA). The model evaluates the dynamic trade-offs/synergies among different ecosystem services under various scenarios, aiming to seek the optimal management approach for enhancing the functionality and optimizing the structure of ESs in the future of the CZTMA. The results indicate the following: (1) From 2000 to 2020, the Ecosystem Service Value (ESV) of the CZTMA gradually declined from 601.57 billion yuan to 584.65 billion yuan. Under the three future scenarios, the ESV also decreased, with the Ecological Conservation Scenario (ECS) experiencing the most minor decline, and the Economic Priority Scenario (EPS) witnessing the most substantial decrease. (2) In the historical period and the 2030 predicted scenarios, there is a predominant synergy among paired ESs in the CZTMA. Throughout the study period, the region’s dominant ecosystem service bundle (ESB) is the high-service ecological regulation bundle, primarily located in the northeastern, western, and southern areas dominated by forests. (3) Based on ESV and urbanization intensity (UI), five different ecosystem management zones were identified: water balance zone (WBZ), coordinated improvement zone (CIZ), ecologically weak zone (EWZ), ecological conservation zone (ECZ), and ecological derivative zone (EDZ). Corresponding management and protection strategies for ecosystem services were proposed. The research findings offer potential solutions for optimizing land use and managing the trade-offs of ESs in metropolitan areas.

The present study investigates the diffusion bonding of leaded-tin bronze (CuSn10Pb10) and 45 steel via surface modification method, i.e., hot-dip tin coating (HDTC) treatment, so as to provide guidance for the application of copper/steel joints. The effect of HDTC treatment on the interfacial microstructure and mechanical performance of CuSn10Pb10/45 steel joint is established. The results show that the interfacial crack is formed during diffusion bonding of CuSn10Pb10 and 45 steel without HDTC treatment. However, HDTC treatment evidently promotes the mutual diffusion of elements between CuSn10Pb10 and 45 steel, and a metallurgical CuSn10Pb10/HDTC 45 steel joint with a transition layer consisting of Fe-enriched solid solution, Cu-enriched solid solution and Cu10Sn3 intermetallic compound is obtained. The CuSn10Pb10/HDTC 45 steel joint at a bonding temperature of 900 °C shows higher shear strength and better ductility than that of CuSn10Pb10/45 steel joint. With the increasing of bonding temperature, the promoted occurrence and aggregation of Cu10Sn3 intermetallic compound in the CuSn10Pb10/HDTC 45 steel bonding interface results in the increase in shear strength, but the decrease in ductility of joint.

To expand the selection range of materials for blades in gas turbines, new single crystal superalloys with different Re contents were developed and the microstructures, high temperature tensile properties and fracture behaviors were investigated. The dendrites and γ+γ′ eutectic are observed in the as-cast superalloys. After heat treatment, the γ+γ′ eutectic in the interdendritic regions is completely eliminated and cubic γ′ phase with regular morphology maintains a coherent relationship with γ matrix. The size of γ′ phase decreases with the increasing Re due to its inhibition effect on the growth of γ′ phase. The three alloys have little differences in strength below 850 °C and possess the maximum tensile strength at 760 °C. However, the strength of 3Re and 0Re alloys is obviously higher than that of 1.5Re alloy at 980 °C due to the higher content of refractory elements. In addition, all alloys have a very obvious work hardening peak below 760 °C before fracture. With the increasing temperature, the characteristics of plastic fracture become more obvious due to the changes of dislocation motion. At 650 °C, the alloys show quasi-cleavage fracture. At 980 °C, numerous dimples can be clearly seen while no slip deformation trace is found, showing obvious dimple aggregation fracture. The γ′ phase elongates along the direction of stress loading, and the γ channel perpendicular to the direction of the stress axis widens. The rafting phenomenon of γ′ phase in the all three single crystal superalloys does not appear, indicating the alloys have good microstructure stability.

In this paper, Ti-27Nb-17Ta-8Zr/HA series composite materials were prepared by spark plasma sintering (SPS) technology. The medical titanium alloy (Ti-27Nb-17Ta-8Zr) with good mechanical properties, wear resistance, and corrosion resistance was combined with the hydroxyapatite (HA) bioactive ceramic with high biological activity and bone-binding ability. Moreover, the density, microstructure evolution, metal/ceramic reaction, mechanical behavior, in vitro bioactivity, and influencing mechanisms of composite materials with different HA contents were studied. The research results indicate that all biological composite materials are composed of β-Ti solution, α-Ti, and ceramic phases (Ti2O, CaTiO3, CaO, TixPy). With the increase of HA content, the compressive strength and yield strength of the composite material show a trend of first increasing, then decreasing, and then slowly increasing. After soaking in SBF artificial simulated body fluid for 5 days, the deposition of elements such as Ca and P on the surface significantly increased, while elements such as Ti, Nb, Ta, and Zr were evenly distributed in the matrix, demonstrating good in vitro mineralization ability and facilitating the attachment and growth of osteoblasts.

In this study, the bonding of a CuW/Al composite with a Ni interlayer was designed and established by vacuum hot-pressing diffusion bonding. The interfacial microstructure was systematically discussed based on experimental characterization and first-principles calculations. The result indicated that the interface consisted of intermetallic compounds (IMCs) of Al3Ni2 and a few of Al3Ni. The interfacial microstructure significantly differed from the interface without the Ni interlayer. The growth kinetics of the Al3Ni2 layer followed a parabolic behavior, which was mainly affected by the volume diffusion mechanism. The interfacial thickness decreased significantly, and the average thickness was ~35 μm. The microstructural evolution revealed that Al3Ni2 was the phase that was formed first. By introducing a Ni interlayer, the interfacial strength was significantly enhanced due to the IMCs that were changed from Al–Cu and Al–W IMCs to Al–Ni IMCs. The maximum shear strength reached 90.9 MPa, which was increased by 76% compared to that of the sample without the Ni interlayer. An analysis of the fracture morphology analysis showed that the crack was prone to exist at the Al3Ni2/Ni interface and presented a cleavage fracture characteristic.

Simultaneously integrating mesocrystalline stacking superstructures, porous nanosheets and defective oxygen vacancies (OVs) into BiOCl crystals is an available strategy to enhance the visible-light-driven photocatalytic activity. Herein, we report a facile etching agent-assisted hydrothermal approach to achieve one-pot fabrication of mesocrystalline BiOCl porous nanosheet stacking superstructures with defective OVs, which show high catalytic activities towards to the visible-light-driven degradation of organic dyes. The formation of stacking superstructure in a mesocrystalline BiOCl is responsibility for increasing the transport of charge carriers. Experimental results and theoretical calculations suggest that the presence of OVs is beneficial to tuning the energy band structure for the improvement of visible light harvesting, prolonging the lifetime and enhancing the oxidation activity of photogenerated charge carriers. Additionally, the porous morphology and thin nanosheet building block could supply abundant active sites for photocatalysis. This research might arouse in-depth investigations on the development of novel precursor-modified strategy for the synthesis of high-active BiOX (X = Cl, Br and I)-based photocatalysts.

As an important mechanical property, tensile behavior has been regarded as an indicator for the creep and thermal mechanical fatigue properties of Ni-based superalloys. The tensile property of Ni-based superalloys is closely related to the amount, size, and distribution of γ′-phase and carbides. To further clarify the tensile deformation mechanism of the CM247LC alloy, this study investigated its solidification characteristics and directionally-solidified and heat-treated microstructure. The dependence of tensile properties on the varied temperature ranging between 650 and 950 °C is discussed in detail. It was found that the deformation mechanism at 650 °C is dominated by the shearing of dislocations into the γ′-precipitates to form the superlattice stacking faults. At 800 °C, the K-W lock leads to the anomalous yield effects. At 950 °C, the deformation mechanism is dominated by the dislocations bypassing the γ′-precipiates. The results provide a comprehensive understanding of the CM247LC alloy and are beneficial for the development of corrosion-resistant Ni-based superalloys.

To obtain higher comprehensive mechanical properties while avoid the adverse effects of Re element on the microstructure and economy of the alloy, a Re-free nickel-based single crystal superalloy is developed based on the Rene N5 single crystal superalloy. The microstructure evolution, compression properties, tensile properties, deformation mechanism and fracture behaviour of the self-designed alloy are investigated. The experimental results show that after the complete heat treatment, cuboidal γ′ precipitates with high degree of regular morphology are formed. The size of γ′ precipitates is about 0.49 μm, and the volume fraction is approximately 61%, which are better than those for a conventional second generation single crystal superalloy. The alloy reaches its maximum compressive and tensile strength at 760 °C and shows excellent microstructure thermal stability and improved mechanical properties. The alloy has an obvious strain hardening stage when the temperature is lower than 760 °C, while the softening stage is not obvious. When the temperature reaches 850 °C, the stress–strain curve of the sample mainly shows that the variable stress increases abruptly at the beginning and then decreases immediately. The tensile fracture of a single crystal at medium and low temperature is characterized by a slip fracture with a certain plastic deformation. A high temperature tensile fracture is characterized by typical plastic deformation, and its mechanism is a creep fracture with a uniform deformation.

Synergistic strengthening is increasingly explored for developing high-performance metal matrix composites. In the present work, copper matrix composites reinforced with carbon nanotubes (CNTs) and TiB2 microparticles were fabricated via electroless deposition, powder metallurgy, hot extrusion, and water quenching. The synergistic strengthening effect of the nano-and micro-reinforcements was elaborated and analyzed based on experimental investigation and theoretical calculation. (1CNT-4TiB2)/Cu composite exhibited a better combination of the tensile strength of 375 MPa with elongation of 32.4% than other composites, representing 86.3%, 71.5%, and 22.8% strength increment in comparison with pure Cu, 4TiB2/Cu composite, and 1CNT/Cu composite, respectively. The strengthening efficiency of CNTs in (1CNT-4TiB2)/Cu composite is markedly higher than that in 1CNT/Cu composite (126.7 and 82.3, respectively), confirming the synergistic strengthening effect in enhancing the mechanical properties. Quantitative analysis and experimental characterization indicated that the thermal mismatch and load transfer mechanism of CNTs were the main factors contributing to the tensile strength enhancement of the composite. The synergistic strengthening effect was attributed to that TiB2 microparticles improved the homogeneous dispersion of CNTs, promoting the proportion of thermal mismatch and load transfer mechanisms. The present work may provide a new sight into improving the synergistic strengthening effect in metal matrix composites.

Influenza A virus (IAV) is a major human pathogen associated with significant morbidity and mortality worldwide. Through serial passage in mice, we generated a recombinant pdmH1N1 2009 IAV, A/Guangdong/GLW/2018 (GLW/18-MA), which encodes an mCherry gene fused to the C-terminal of a polymerase acidic (PA) segment and demonstrated comparable growth kinetics to the wild-type. Nine mutations were identified in the GLW/18-MA genome: PA (I61M, E351G, and G631S), NP (E292G), HA1 (T164I), HA2 (N117S and P160S), NA (W61R), and NEP (K44R). The recombinant IAV reporter expresses mCherry, a red fluorescent protein, at a high level and maintains its genetic integrity after five generations of serial passages in Madin-Darby Canine Kidney cells (MDCK) cells. Moreover, the imaging is noninvasive and permits the monitoring of infection in living mice. Treatment with oseltamivir or baicalin followed by infection with the reporter IAV led to a decrease in fluorescent protein signal in living mice. This result demonstrates that the IAV reporter virus is a powerful tool to study viral pathogenicity and transmission and to develop and evaluate novel anti-viral drugs, inhibitors, and vaccines in the future.

In the present work, the ultrafine-grained W-25 wt.%Cu composites doped with multi-walled carbon nanotubes (CNTs) have been prepared through combined processes of high-energy ball-milling, liquid-phase sintering and infiltration. Furthermore, the microstructure, hardness and electrical conductivity of the ultrafine-grained W-Cu composites doped with different contents of CNTs were investigated. Meanwhile, the wear resistance, compressive performance at different temperatures and arc erosion resistance were evaluated in comparison with the W-Cu composite without CNTs. The results revealed that the hardness, wear resistance, compressive performance and arc erosion resistance of the W-Cu composites doped with CNTs were enhanced dramatically due to the introduction of tungsten carbide phases after sintering and infiltration. Keywords: W-Cu composite, CNTs, Tungsten carbide, Wear resistance, Compressive performance

In order to achieve a reasonable balance between the high electrical conductivity and high tensile strength of TiB2 particles (TiB2p) and TiB whiskers (TiBw) reinforced copper matrix composites prepared by in situ reaction casting, the effects of reaction temperature and heat treatment time on the electrical conductivity and tensile strength of composites were studied. The results show that the electrical conductivity increased while the tensile strength decreased with the increase in reaction temperature from 1300 °C to 1500 °C. With the increase in heat treatment time, the electrical conductivity increased, while the tensile strength of the composites increased first and then decreased. The electrical conductivity and tensile strength of composites are related to the degree of in situ reaction at liquid or solid state, and the reasons for the improved performance are also discussed. Finally, two optimized preparation processes are proposed by cooperative controlling the reaction temperature and heat treatment time, the comprehensive properties of (TiB2p+TiBw)/Cu composites are 79.6% IACS/603 MPa and 83.7% IACS/602 MPa, respectively.

In this study, the W (10–20%)–Cu composites were simultaneously fabricated using commercial, graded commercial, and graded jet-milled W powder. The results show that the W–Cu composites prepared with the graded jet-milled W powders have the highest density and best comprehensive performance due to the combined effect of the particle gradation and jet-milling treatment. Particle gradation is employed to increase the packing density of powders, thereby increasing the relative density of the compressed W skeleton, and the rounded powder with narrow particle size distribution after jet-milling treatment is used to reduce the enclosed pores formed during the process of compacting and infiltration. W–Cu composites with a high density of 16.25 g/cm3 can be directly obtained by conventional compacting at a low pressure of 300 MPa and following infiltration.

The continuous network structure induced by carbon nanotubes (CNTs) was introduced to TiB2/Cu composites by electroless deposition, slurry dispersion and powder metallurgy to enhance arc erosion resistance. The arc erosion characteristics of the TiB2/Cu-CNT composites at a current ranging from 10 A to 20 A were investigated. The mechanisms of enhanced arc erosion resistance by the CNT network structure were elaborated based on microstructure and physical characteristics as well. The results show that with the introduction of continuous CNT network structure, arc energy was reduced by more than 83%, there were almost no fluctuation of arc energy and the welding force was relatively low at current above 15 A for TiB2/Cu-1.2 vol% CNT composite in comparison with the CNT unreinforced TiB2/Cu composite. The continuous network structure facilitated the cathode arc motion and dispersed the cathode arc, mitigating the concentrated deterioration of arc erosion. Simultaneously, CNTs could float much easily at the surface of molten pool to weaken the Cu splashing. The CNT network structure delayed the formation of the deeper crater on the cathode and the protrusion with a sharper tip on the anode. Furthermore, it could prevent the formation of cracks and fracture of anode protrusion. Keywords: TiB2/Cu-CNT electrical contact materials, Designing and tailoring microstructure, The CNT network structure, Arc erosion characteristics, Arc erosion mechanism

Considering the advantages and disadvantages of CuW alloys with different single particle size of tungsten powder, CuW alloys with three kinds of tungsten powders: ultramicron (50 μ m), micron(6–8 μ m), submicron(0.4 μ m) were prepared by the infiltration method. Microstructure of the CuW alloy with different grading ration of tungsten powder were characterized via field-emission scanning electron microscope (SEM). The Vacuum electrical breakdown properties were studied by electrical breakdown test. The results shows that the grading tungsten powders can form a variety of W-W sintered necks, strengthen the tungsten skeleton. SEM results show that a suitable ratio of grading tungsten powders can make the infiltrated copper phase more dispersed and uniform. Compared with the tradition CuW alloy, the conductivity is greater than 53.5%IACS, with the lowest hardness of 203HB, the lowest CuW/CrCu bonding strength of 417 MPa and the highest of 495 MPa, the hardness and electrical conductivity increased by 20%–30%, the bonding strength of new CuW/CrCu monolithic materials increased by 20%, vacuum electrical breakdown properties performed good.

The Cu–Ni–Mn–Fe alloy is prepared to study its precipitation behavior and mechanical properties during aging under elevated compression stresses. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD), hardness and tensile tests are used for this investigation. The results indicate that the stress-aging treatment leads to the formation of fine, equiaxed grains and twins within the matrix of Cu–Ni–Mn–Fe alloy. During the stress-aging, the density of θ -MnNi precipitates initially decreases and then increases. The stress is further increased from 220 to 385 MPa, the vacancy concentration and dislocation density increase rapidly owing to creep deformation, while the strain-induced effect accelerates the precipitation of θ -MnNi. The results show that the tensile strength and hardness of Cu–Ni–Mn–Fe alloy initially decrease and then increase, and the tensile strength and hardness of the Cu–Ni–Mn–Fe alloy are 890 MPa and 274 HB under the compressive stress of 385 MPa, and the elongation remains at 8.72%. It is mainly attributed to the application of compression stresses during aging, which can enhance both the strength and ductility of the alloy.

This paper presents a systematic study of the precipitation strengthening mechanism in polybasic Cu–Ni–Mn–Fe alloy. The effect of aging treatment on the microstructure, morphologies and phase transition of the Cu–Ni–Mn–Fe alloy were analyzed and discussed using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and differential scanning calorimeter (DSC), respectively. The θ-MnNi precipitates with a size of 50–100 nm, mainly formed during aging, were considered as the source of the aging strengthening. In addition, there is a semi-coherent between the plane (111) of the θ-MnNi precipitates and the plane (200) of the α -Cu matrix. The density of θ-MnNi precipitates increases with the increase of the aging time. The hardness, yield strength and ultimate tensile strength of the aged alloy increase from 127 to 366HB, 217 to 788 MPa, and 433 to 842 MPa, respectively, which is attributed to precipitation strengthening.

The thermodynamics and kinetics methods had been applied to study the effects of the deposition temperature, the reaction gas ratio and the dilution gas on Si _3 N _4 formation in the SiCl _4 -NH _3 -H _2 system. The studies revealed that raising the deposition temperature would accelerate the chemical reaction and increase Si _3 N _4 yield below 1400 K, higher temperature prompted the side reactions. With the increase of NH _3 concentration, the content of Si _3 N _4 in the reaction products also increased. As the diluent gas, H _2 could accelerate the reaction and the deposition of Si _3 N _4 . However, the excess dilution gas would carry away the reaction gas and inhibit the reaction. The comprehensive effect of temperature and gas ratio on Si _3 N _4 deposition were also analyzed by the three-dimensional figures. Finally, the optimal conditions for Si _3 N _4 preparation were suggested.

Metal gallium was evaporated onto ZnS films by physical vapor deposition method and then the thermal oxidation in the air was subsequently performed for the growth of Ga-doped ZnO films. The microstructures, photoluminescence (PL) and optical absorption properties of the Ga-doped ZnO films prepared under different deposition and oxidation conditions were investigated. The results showed that certain Ga doping can decrease the defects level, improve the crystallinity of ZnO films, and it became more effective with the extension of oxidation time. As the oxidation time increased, the Ga-doped ZnO films became more compact and uniform, displaying higher crystallinity. In addition, the optical band gaps of the ZnO films increased, the PL intensity of the visible emission decreased, and the luminescent center of the visible emission changed. Among them, the 505 nm emission resulted from oxygen vacancy, while the 539 nm emission was associated with oxygen interstitial.

The ultraviolet photoluminescence of ZnO/ZnGa2O4 composite layer grown by the thermal oxidation of ZnS with gallium was investigated by the time-resolved photoluminescence as a function of measuring temperature and excitation power. With increase of excitation power, the D0X emission is easily saturated than the DAP emission from ZnO/ZnGa2O4 composite layer, and which is dramatically enhanced as compared with that from pure ZnO layer grown without gallium. The radiative recombination process with ultra-long lifetime controlled the carrier recombination of ZnO/ZnGa2O4 composite layer.