The study focused on TA1 pure titanium as the research object. The electron back scatter diffraction （EBSD） technology and tensile testing were used to characterize the microstructure，texture，and mechanical properties of TA1 pure titanium plates rolled under different deformation regimes. The microstructure evolution process of TA1 pure titanium plates during hot rolling and the influence of deformation degree on mechanical properties were analyzed. In terms of microstructural evolution during hot rolling，at the initial stage of deformation，plastic deformation mainly occurred through twinning and slip. Most grains exhibited plastic deformation，with a large number of low-angle grain boundaries （LAGBs） and twins generated inside the grains. Meanwhile，fine recrystallized grains emerged at the grain boundaries. As the deformation degree increased，the equiaxed structure was flattened，and the dynamically recrystallized grains gradually increased. With small deformation，both slip and twinning participated in plastic deformation，and the proportion of twin boundaries was relatively high. However，with the increase in deformation，the proportion of twin boundaries decreased，and dislocation slip became the main mode of coordinating plastic deformation. Additionally，internal stress promoted the transformation of LAGBs into high-angle grain boundaries （HAGBs），leading to the formation of recrystallized grains. Mainly because at small deformations，the dislocation density was low，and there were relatively few slip systems that could be activated，so twinning was required to coordinate the deformation. As the deformation increased，the initially formed twin boundaries underwent torsion and tilting，and transformed into ordinary HAGBs，which destroyed the specific orientation relationship between the twins and the matrix. At the same time，the increase in dislocation density promoted the activation of more slip systems，leading to the formation of a large number of LAGBs. At this time，the main way to coordinate plastic deformation was dislocation slip. Additionally，as the deformation increased，the internal stress increased，which promoted a large number of LAGBs to grow into HAGBs，resulting in the formation of fine recrystallized grains. Regarding texture evolution，significant changes were observed in the {0001} pole-figure texture during hot rolling. In the small deformation stage，the initial three-peak texture disappeared，and part of the {0001}∥transverse direction （TD） texture transformed into {0001}∥ rolling direction （RD） texture，forming a two-peak texture. With further deformation，the {0001}∥RD texture vanished，and a strong single-peak {0001}∥TD texture was formed，with the texture strength increasing. The inverse pole figures showed that the main texture types during hot-rolling deformation were <01$\overline{1}$0> ∥RD texture and <0001> deviated by 30° parallel to normal direction （ND） texture. The main difference laid in the change of strength. At small deformations，the <01$\overline{1}$0> ∥RD texture developed into the main texture，and then the strength of this texture and the ∥ND texture alternated. For the mechanical properties at room temperature，as the hot-rolling deformation degree increased，the tensile and yield strengths of the plates increased，while the elongation after fracture decreased. This was mainly due to grain refinement，an increase in dislocation density，and work hardening during deformation，which led to an increase in strength and a decrease in plasticity. This was mainly because as the degree of deformation increased，the original recrystallized equiaxed structure was fully fragmented，and the grains were fully refined，thus increasing the strength of the plate. At the same time，with the increase of cumulative deformation，the dislocation density increased，which promoted the distortion of the crystal lattice，leading to an increase in the internal energy of the material and an increase in internal stress. As a result，the plasticity of the plate decreased，and work hardening also increased the strength of the plate. During the process of plastic deformation，the stress concentration formed by the dislocation pile-up would promote the initiation of cracks，while the grain boundaries would hinder the propagation of cracks. Therefore，cracks were likely to propagate on the coarse grains. In addition，the coarser structure was conducive to the continuous occurrence of slip，which in turn led to uneven deformation. The deformation twins generated in the initial stage would cause the crystal to rotate，enabling the slip to continue，thereby releasing stress，weakening the initiation of cracks，and exhibiting better plasticity. The plates hot-rolled at 750 ℃ had the same texture type，which was mainly the cylindrical texture parallel to RD. Moreover，during the room-temperature tensile test along the TD，the {10$\overline{1}$0}<11$\overline{2}$0> prism plane slip system was relatively easy to activate. Therefore，for the plates obtained at the same deformation temperature，the influence of the texture on the mechanical properties was basically the same. The mechanical properties of the plates obtained at the same deformation temperature were mainly affected by the grain size. This research provided crucial theoretical support for the optimization of the processing technology of TA1 pure titanium，which was of great significance for improving the performance and quality of TA1 pure titanium products in practical applications.

With the rapid development of the global economy，various kinds of energy sources have been developed one after another. In the existing energy structure，people still rely more on traditional energy sources. The excessive use of traditional energy sources such as oil and coal has led to serious environmental problems and energy crises. The search for non-polluting and renewable clean energy is not only a major challenge in the field of energy and environmental sciences，but also a problem that must be solved by human society to achieve sustainable development. Biomass is a rich renewable resource，originating from photosynthesis in nature，and is regarded as a very promising class of energy materials due to its non-pollution，large reserves，and degradable characteristics. Among many biomasses 5-hydroxymethylfurfural （HMF） and furfural （FF） show excellent development potential，they can be extracted from lignocellulosic treatment of biomass and can be regenerated quickly，so the reserves are very abundant. When co-electrolyzed with water，the anodic furfural species are oxidized to additional products，HMF to 2，5-furandicarboxylic acid （FDCA） and FF to furfuryl acid （FAC），while hydrogen is produced at the cathode. The system of electrocatalytic furfural/water co-point decomposition is conducive to the generation of renewable hydrogen energy with no pollution and low energy consumption，and an ultra-efficient hydrogen production system with bipolar hydrogen production can also be achieved by rational design of the catalyst. Among the products of electrocatalytic oxidation FDCA is recognized as a monomer that can be synthesized into plastics due to its unique conjugated rigid ring and dicarboxylic acid structure of benzene dicarboxylic acid，which can not only alleviate the problem of plastics pollution，but also reduce the dependence on fossil resources. Electrocatalytic oxidation is capable of operating at ambient temperature and pressure，making it an environmentally friendly and economically viable method of energy production compared to conventional thermal catalysis. Both precious and non-precious metals are used to catalyze such reactions. Among them，non-precious metals have received widespread attention due to their cost-effectiveness and availability compared to precious metal catalysts. Among the non-precious transition metals，the low cost of copper-based catalysts shows a significant advantage，and also copper is currently the most effective catalytic substance for the electrocatalytic oxidation of FF at low potentials. However，the stability and selectivity of copper-based catalysts in the catalytic process are still a great challenge，hindering their wide industrial application in this reaction system. Many research teams have worked to break through the shortcomings of copper-based catalysts in electrocatalytic furfural oxidation. Although the application of copper-based catalysts is still in its infancy，they still show great potential in reducing the production cost and improving the catalytic efficiency. This paper reviewed the recent progress in the application of copper-based catalysts in the co-electrolysis of low-energy water and furfural for hydrogen production，and in-depth studies of optimistic strategies such as doping engineering，multi-component synergism，vacancy engineering，interfacial engineering，and structural control have been carried out. These approaches aimed to address the existing limitations and improve the overall performance of copper-based catalysts. Doping engineering improved the catalytic performance of catalysts by introducing a small number of dissimilar atoms into the catalyst matrix，which significantly altered the electronic structure，geometry and surface properties of the catalysts. Multi-component synergy utilized the advantages of combining different elements or compounds to achieve synergistic effects beyond those of individual components. Vacancy engineering created defects in the catalyst material that could act as catalytic activity centers，thereby improving performance. Interfacial engineering focused on optimizing the interaction between the catalyst and electrolyte，which was essential for efficient charge transfer and reaction kinetics. Finally，structural modulation involved the precise manipulation of the physical structure of the catalyst to optimize the catalytic active surface area and reaction sites. In addition，this paper looked at future research directions，with particular emphasis on the use of advanced technologies such as in-situ characterization techniques and artificial intelligence. In-situ characterization techniques were able to monitor the behavior of catalysts under operating conditions in real time，thus reflecting the catalytic mechanism and active sites during the reaction process，which was of great significance in guiding the further development of this system. Artificial intelligence，an indispensable tool in the future development of materials science，provided the ability to predict catalyst performance based on large data sets through machine learning algorithms to guide the design of more efficient and stable catalyst systems. In conclusion，although challenges remained in the stability and selectivity of copper-based catalysts，ongoing research efforts were expected to overcome these obstacles. It was becoming increasingly feasible to develop efficient and stable catalyst systems by employing innovative optimistic strategies and utilizing cutting-edge technologies. It was expected that these advances would greatly facilitate the practical application of these technologies，promote sustainable energy solutions and address the urgent need for clean energy alternatives in the context of the escalating environmental crisis.

Oil-water emulsion is a stable colloidal dispersion made of microscopic droplets dispersed in an immiscible continuous phase，which is widely used in the fields of petrochemicals，food processing，clinical pharmaceuticals，and cosmetics production. Generally，oil-water emulsion is obtained from wastewater，and if it is discharged without proper treatment，it will cause great harm to life and the environment. Compared with traditional separation technology，membrane separation technology has several advantages，such as high separation efficiency，no phase change，low energy consumption，low cost，and simple device，thus becoming the researchers' first choice to treat oily wastewater. Common two-dimensional demulsification separation membrane materials have the unique advantages of uniform pore size，high demulsification efficiency，and controllable wettability，which can realize efficient demulsification and separation of oil-water emulsion through the synergistic effect of nanopores and surface properties. This review firstly classified and introduced the demulsification mechanism of the demulsification materials. Demulsification mechanisms could be divided into four main categories：sieving demulsification，physical demulsification，chemical demulsification，and electrostatic demulsification. Sieving demulsification used the pore size of the material to screen the droplets，and then intercepted them into a narrow space to contact each other and combine，which ultimately separated the droplets of emulsion，with a smaller pore size，wettability with numerous different advantages. Physical demulsification used a particular form of the material （various micro and nanostructures） or irregular pores on the emulsion droplets to physically destroy the droplets，leading to the deformation and destabilization of the emulsion. Chemical demulsification was the use of chemical components on the substrate or chemical demulsifiers and oil droplets or surfactants to react，reducing the stability of the oil/water boundary membrane，to break the emulsion. Electrostatic demulsification was based on the electrostatic interactions between charged substances and charged droplets to destabilize droplets for demulsification，which was usually defined as the charge shielding effect，and had the advantages of simplicity，rapidity，and non-introduction of external contaminants. Secondly，the design principles and critical parameters of two-dimensional demulsification separation membrane materials were described in detail. The design principles mainly included：（1） selection of a suitable demulsification mechanism，when designing membrane materials，the characteristics of specific emulsions should be considered comprehensively，and the appropriate demulsification mechanism should be selected according to the desired demulsification effect；（2） good hydrophilic and hydrophobic properties，so that the membrane material could be adsorbed at the oil/water interface，reduced the interfacial tension，and promoted the aggregation，fragmentation and separation of oil droplets in the emulsion；（3） good biodegradability and environmental friendliness，could be biodegraded in the natural environment，and would not cause pollution or harm to the environment. Important design parameters included，but were not limited to：pore size，porosity，surface properties，material morphology，particle size，and chemical composition. Finally，four types of two-dimensional demulsification separation membrane materials and the corresponding typical cases were comprehensively reviewed. Two-dimensional demulsification membrane materials could be classified into metal-based membranes，inorganic oxide membranes，electrostatically spun polymer membranes，and biomass-based fiber membranes according to the different membrane-forming materials. Through in-depth analysis and discussion of the cutting-edge research in this field，it aimed to provide references and help for the related research，promote the development of oil-water emulsion wastewater treatment technology，and realize efficient and environmentally friendly wastewater treatment and resource recovery.

Titanium alloy offers high specific strength，fatigue resistance，and corrosion resistance，making it widely applicable in aviation，aerospace，weaponry，petroleum，and the chemical industry. TA19 titanium alloy，also known as Ti-6242S，features medium strength，good thermal stability，and creep resistance，is widely used in advanced engines and aircraft. As we all know，titanium alloy forgings mainly adjust the proportion and size of α phase and β phase through hot deformation and heat treatment to meet application needs. Currently，the relationship between the heat treatment process，structure，and properties of TA19 titanium alloy is relatively well understood. It is generally believed that as the solid solution temperature increases，the content of the primary α phase decreases，while the strength and high-temperature creep properties increase. For the thermal deformation process of TA19 titanium alloy，the influence of individual deformation process parameters such as deformation temperature and strain rate on the evolution of structure and orientation is primarily studied through thermal simulation experiments. Therefore，there is a lack of intuitive observation and analytical research on the structure and texture during multi-fire forging. This article used a TA19 titanium alloy ingot with a diameter of 600 mm and a weight of 3 ton on a 20 MN fast forging machine to prepare a finished bar with a diameter of 260 mm through a total of 16 forging passes，with an up setting amount of 45% for each pass. Among them，in the 1st to 3rd passes，the bar blank was upset and stretched at 1150，1100，and 1050 ℃，respectively，and was air cooled after forging；in the 4th and 5th passes，it was upset and stretched at T_β-35~40 ℃ （T_β is transformation temperature of β→α），while the T_β is 1004 ℃，and was air cooled after forging；in the 6th pass，it was upset and stretched at T_β+50 ℃，and water cooled after forging；In the 7th to 15th passes，it was upset and stretched at T_β-35 ℃，and air cooled after forging；in the 16th pass，it was upset and rounded at T_β-40 ℃，and air cooled after forging. Samples were taken from the center，mid-radius，and surface positions on the cross section of the bar blank after the 5th，6th，9th，12th，and 15th pass forging. Scanning electron microscopy （SEM） and electron backscattered diffraction （EBSD） techniques were used to systematically analyze the microstructure and orientation characteristics of the α phase and β phase. The texture and orientation characterization were performed using an Ultra 55 field emission scanning electron microscope （FE-SEM） equipped with an EBSD probe. The texture analysis was conducted using Channel 5 orientation analysis software. The research results showed that although varying degrees of variant selection occurred after the β→α transformation，resulting in transformation textures，the repeated upsetting and stretching during the forging of TA19 titanium alloy bar prevented the formation of strong α phase transformation and deformation textures. After forging in β region，multiple clusters of α phase clusters were formed within the original β phase，with the orientation of α phase clusters predominantly in the <0001> direction，perpendicular to the length of the bar blank. When the actual temperature at the end of forging was higher than T_β，the lamellar α phases in the cluster did not participates in deformation. When the actual temperature at the end of forging was lower than the T_β，lamellar α phases would undergo a certain degree of fragmentation and deviate from the original orientation of the cluster，causing <0001> texture to weaken. When forging in the α+β region，both the α phases and residual β phases participated in deformation. As the number of forging passed in the α+βregion increases，lamellar α phases continued to become equiaxed，and the number of new equiaxed α phases transformed from the deformed residual β phases increases. The <0001> texture gradually weakened and shifted to <10$\overline{1}$0> and < 11$\overline{2}$0> texture. The weakening of the macrotexture of α phases mainly relied on the increase in newly formed equiaxed α phases. This was because the orientation shift of lamellar α phases caused by deformation was limited，while the orientations of equiaxed α phases formed by the transformation of deformed residual β phases were more varied. In addition，during the entire forging process，the equiaxation of lamellar α phases on the surface of the bar blank occurred more quickly，followed by the mid-radius position，and was the slowest in the center. This showed that the lower forging temperature and the more complex the stress state were more beneficial to the equiaxation of α phases. The purpose of this article was to systematically and in-depth analyze the structure and texture evolution rules of the α phase and β phase during the forging process of TA19 titanium alloy，and to provide theoretical support for the optimization of bar preparation process.

With the development of industrialization，the extensive use of fossil fuels has resulted in the accumulation of increasing amounts of carbon dioxide （CO₂） in the atmosphere. This has caused significant environmental problems （e.g.，global warming and rising sea levels，as well as an energy crisis）. The technology of CO₂ capture，transportation，and reuse or safe storage is helpful to realize the coordination and integration of energy conservation，waste utilization，and carbon reduction and establishing a new CO₂ circular economy industrial chain. The traditional methods of utilizing carbon dioxide include photocatalysis，thermal catalysis，biocatalysis，and electrocatalysis. Among these approaches，using renewable electricity to convert carbon dioxide into high-value hydrocarbons and oxygen-containing compounds is one of the important methods for realizing the resource utilization of carbon dioxide. Copper is a catalyst that can efficiently reduce CO₂ to produce multi-carbon products. Due to the complex thermodynamic and kinetic processes involved in electrocatalytic carbon dioxide reduction （CO₂RR），numerous reaction pathways，intermediates，and products are caused. Single-component copper catalysts cannot efficiently achieve C–C coupling. The deep reduction of CO₂ still faces challenges such as high overpotential，low Faraday efficiency，and current density of C₂₊ products，and industrial applications are limited. It is generally believed that the primary reason for the low Faraday efficiency and current density of C₂₊ products on Cu-based catalysts is that Cu is difficult to activate CO₂ to generate *CO. The introduction of a second catalyst improves the conversion efficiency of converting CO₂ to CO，enhances the local concentration of *CO at the interface （increased Faraday efficiency and current density），reduces the energy barrier of C−C coupling （reduce overpotential），and enhances the overall efficiency of the deep reduction of CO₂. CO is an important intermediate in the production of methane，methanol，ethylene，ethanol and other products. After the formation of a CO intermediate （*CO），the CO₂ reduction follows a similar path to the electrocatalytic CO reduction reaction （CORR）. Tandem catalysis can eliminate the need for purifying and separating intermediates at each step，and can effectively addressing the problem of complex CO₂RR reaction pathway and numerous intermediates. The entire catalytic process is divided into several stages，with each stage being carried out at different catalytic sites. This arrangement is beneficial for achieving the optimal binding energy at each stage of the reaction，reducing the thermodynamic reaction energy barrier，accelerating the reaction kinetics and achieving high selectivity，high current and fast rate to produce C₂₊ products. A variety of catalysts are capable of converting CO₂ to CO. However，further reduction of CO occurs almost exclusively on copper. Combining the catalyst that can efficiently produce CO with the Cu catalyst that effectively catalyzes the C−C coupling to form a tandem catalyst is an emerging design strategy. This strategy aims to break the linear proportional relationship and enhance the selectivity and formation rate of C₂₊ products. Due to the ligand effect，electronic effect，and geometric effect between different metal elements，the CO₂RR performance of Cu-based catalysts in CO₂ reduction reaction can be greatly improved by incorporating other metal elements （Au，Ag） in conjunction with Cu. However，precious metals have drawbacks such as high cost，poor long-term stability，and low natural reserves，which impede the commercialization process. Non-metallic materials，such as carbon-based materials，single atoms，and polymers，offer the advantages of excellent chemical stability，electrical conductivity，wide source of raw materials，and controllable structure. making them potential candidates for series connection with copper. Based on this design strategy，many series catalysts have been developed，and a series of research results have been achieved，which greatly promoted the development of CO₂RR. In this review，we first introduced the basic principles of electrocatalytic carbon dioxide reduction，explained its fundamental reaction mechanism and potential pathways to generate C₂₊ products，and elucidated the design principles and precautions of copper-based tandem catalysts. Secondly，the research progress of copper and metal components in series （alloy nanostructures，heterostructures，core-shell structures） and copper and non-metal components in series （copper-carbon，copper−M-N-C，copper-polymer） in the field of CO₂RR was systematically summarized and discussed，based on the different series components. The problems that should be paid attention in the design of copper-based series catalysts （such as low series current density，single series mode，easy desorption of CO，difficult further coupling） and the problems still existing in industrial applications （such as difficult separation of reduction products，low energy conversion efficiency，limited reaction device，and slow anode half reaction） were pointed out. Finally，future research challenges and opportunities were discussed.

Heterojunction （HJT） solar cells have advantages such as high conversion efficiency，short process，and low temperature process （below 200 ℃）. However，Sn60-Pb40 alloy currently used in the HJT manufacture process has a soldering temperature of up to 230~240 ℃. Such high connection temperatures will not only damage the low temperature made silver surface finish，but also increase the solar cell breakage rate. Therefore，the assembly of heterojunction solar cells in the photovoltaic industry has put forward a low-temperature joining demand. This has once again attracted attention to the cost-effective Sn-Bi low-temperature solder. Based on reducing Bi to 57%，this study added 0.1% and 0.9% Sb/Ag/Ni trace elements respectively to observe the effects of different elements on the melting characteristics，microstructure，and mechanical properties of eutectic （nearby） alloys. Among them，trace elements Sb，Ag，and Ni were all prepared by vacuum sealing and muffle furnace melting during alloy melting. The thermal effects of physical or chemical changes in the sample during heating were characterized using differential scanning calorimetry （DSC，Pyris Diamond） analysis. By observing the changes in the endothermic and exothermic peaks of the alloy on the differential thermal curve，it was possible to determine whether there were new phases generated within the microstructure after microalloying and their effects on melting point and undercooling. Subsequently，scanning electron microscope （SEM，JSM-6480） equipped with energy dispersive spectroscope （EDS） was used for microstructure and composition characterization. And the phase analysis was conducted on an X-ray diffraction analyzer （XRD-6000） . Tensile tests of Sn-57Bi-x（0.1，0.9）Sb/Ag/Ni were implemented at a strain rate of 0.01 s⁻¹ at room temperature to investigate the influence of microelements on the mechanical behavior. The results showed that a small amount of Sb （Sn-57Bi-0.1Sb） mostly existed in solid solution form. When the Sb content reached 0.9% Sb，SbSn phase was found in XRD peak，no SbSn phase was observed under SEM though，indicating that Sb mainly existed as SbSn phase. In order to better understand the formation of SbSn phase，a vertical cross-sectional phase diagram of Sn-57Bi-（0~1）Sb was drawn. From the phase diagram，it was observed that when the Sb content was greater than 0.79%，the primary phase of SbSn would be formed. When the content was lower than this，it should be the precipitated phase of SbSn. Due to the low solid solubility of Ag element in Sn and Bi phases，adding 0.1% Ag to Sn-57Bi alloy revealed Ag₃Sn intermetallic compounds in the microstructure of the alloy. This compound was between the two phases of Sn and Bi，and was in the form of granules and short rods，small in size，generally not exceeding 5 μm. Diffuse distribution in β-Sn phase was quite moderate between the Sn and Bi. When the Ag content was 0.9%，the alloy β-Sn，the size of Sn dendrites significantly decreased，and at this time，Ag₃Sn compounds，as nucleation particles，were mainly distributed inside the Sn matrix in a long strip like aggregation，with a significant increase in size. Like Ag element，Ni added to Sn-57Bi alloy formed Ni₃Sn₄ intermetallic compound phase. When the content of Ni was 0.9%，the size of Ni₃Sn₄ intermetallic compound phase was coarse，even reaching above 200 μm. Generally，these three elements doping reduced the eutectic interlayer spacing and refined the structure，with Ag having the most significant refining effect. And the three elements doping all had strong strengthening effects，and their UTS was higher than that of Sn-58Bi alloy. The maximum tensile strength of Sn-57Bi-0.9Ag alloy was 75.08 MPa，which was 24.0% higher than that of Sn-58Bi eutectic. The minimum elongation of Sn-57Bi-0.9Ni alloy was 13.2%，which was 54% lower than that of Sn-58Bi eutectic. So both Ni and Ag elements strengthened the alloy while damaging the elongation. Although Sb element had a relatively small effect on the tensile strength and elongation of the alloy，it could balance the strength and plasticity indicators. While improving the tensile strength，it also enhanced the elongation of the alloy，Sn-57Bi-0.1Sb alloy had more advantages as a photovoltaic solder alloy.

Aluminum and its alloys find extensive applications in the aerospace，electronic information，and automobile industries owing to their advantages of lightweight，high specific strength，good ductility，excellent corrosion resistance，favorable machinability，and moderate price. However，aluminum and its alloys are highly susceptible to contamination by reacting with water vapor in the air during the melting and casting process. This reaction leads to the production of hydrogen and oxide inclusions. To enhance the metallurgical quality of aluminum alloy melts，flux-based purification treatment technology is commonly employed for removing hydrogen and oxide inclusions from them. Currently there is limited research on the strategy of designing flux compositions for purifying aluminum alloy melts，hence further exploration is required. This study investigated the influence of rare earth composite flux on melt purification treatment，as-cast microstructure，and mechanical properties of 6111 aluminum alloy. Firstly，four types of rare earth composite fluxes （YH-1~YH-4） were developed based on a comprehensive investigation of the thermophysical parameters of molten salt using differential scanning calorimetry （DSC） and molten property measurement instrument. The melting points and viscosities of the fluxes were determined. Secondly，the purification effect，as-cast microstructure，and mechanical properties of 6111 aluminum alloy were comprehensively evaluated through optical microscope （OM），scanning electron microscope （SEM），and mechanical performance testing. Finally，the correlation between the purification effect achieved by rare earth composite fluxes during melt purification treatment and the resulting microstructure and properties of 6111 aluminum alloy was discussed. The DSC results indicated that the melting points of four rare earth composite fluxes （YH-1~YH-4） were approximately 570 ℃，whereas the commercially available flux （ST#） exhibited a melting point around 630 ℃. All four types of rare earth composite fluxes demonstrated lower melting points compared to their commercially available counterparts. Furthermore，measurements of molten properties revealed that the viscosities of all four types of rare earth composite fluxes were also lower than that of the commercially available flux. Metallographic microstructure analysis showed more pores and inclusions in untreated as-cast aluminum alloy samples，treated ones had fewer and smaller ones. Furthermore，statistical analysis of the area fraction of inclusion indicated that the aluminum alloy samples without flux purification treatment had the highest recorded value at 2.96%. Meanwhile，the area fraction of inclusions in the aluminum alloy samples purified by YH-1~YH-4 rare earth composite fluxes and ST# series fluxes are 1.14%，1.45%，0.75%，0.77%，and 1.13%，respectively. The results of metallographic microstructure analysis and inclusion area fraction measurement demonstrated that all four types of rare earth composite fluxes significantly enhanced the metallurgical quality of the aluminum alloy samples. This improvement can be attributed to the ability of fluoride compounds present in rare earth composite flux compositions （such as Na₃AlF₆ and CaF₂） to dissolve and eliminate oxide impurities，or it may be due to a reaction between rare earth compounds LaF₃ and CeF₃ in the composite fluxes with the molten aluminum alloy，effectively removing hydrogen and oxide impurities from the melt. Furthermore，examination of average grain size revealed that untreated 0# aluminum alloy exhibited the largest average grain size at approximately 120 μm，while treatment with YH-3 rare earth composite flux resulted in a significant reduction in average grain size for the treated 3# aluminum alloy sample to about 65 μm. In summary，grain size，pores，and inclusions had a significant impact on the mechanical properties of aluminum alloy. After undergoing purification treatment with rare earth composite fluxes，there was a reduction in grain size as well as pores and inclusions，consequently improving the hardness，tensile strength，and elongation of the aluminum alloy. Notably，YH-3 rare earth composite flux exhibited an optimal purification effect on aluminum melt by reducing inclusion area fraction from 2.96% to 0.75%，increasing Vickers hardness from HV 61.9 to HV 69.3，lifting elongation rate from 4.3% to 13.5%，and boosting tensile strength from 95.4 to141.5 MPa.

Niobium （Nb） has been widely used in aerospace，medical，and superconducting fields in recent years due to its advantages of high melting point，excellent high temperature strength，good biocompatibility，and high critical temperature of superconductivity. The molten salt electrodeposition method can efficiently，controllably，and economically prepare Nb coatings，which have high purity，compactness，and good adhesion to the substrate. In the selection of molten salt system，fluoride system is toxic and corrosive to equipment，which is not conducive to engineering application. The coatings prepared by traditional binary chloride systems have poor compactness and poor adhesion with the substrate. By adding CsCl to the NaCl-KCl molten salt，a continuous and dense Nb coating can be prepared，while the introduction of Cs ions helps to stabilize the Nb complex ions in the active salt，K₂NbF₇，and at the same time reduces the tendency of the co-deposition of oxygen-containing impurities in the molten salt. However，this system is susceptible to deterioration of the quality of the coating，such as nodules，due to concentration polarization when direct current （DC） is used for long-time electrodeposition. To improve the surface quality and mechanical properties of Nb coatings prepared by the traditional DC electrodeposition process，this paper investigated the influence of the pulsed electrodeposition process on the organization and properties of Nb coatings，revealed the mechanism of the influence of the pulsed electrodeposition process parameters on the organization and properties of Nb coatings，and realized the optimization of the preparation process of Nb coatings. The used support salt composition in this study was 17.6% NaCl-22.4% KCl-60% CsCl，and the active salt composition in the mixed molten salt was K₂NbF₇ with a Nb ion concentration of 2.4%. The cathode used for electrodeposition was a Mo plate and the anode was a Nb crucible. The effects of pulse electrodeposition process parameters such as average current density，frequency，and duty ratio on the organization and microhardness of Nb coatings were investigated separately. The results showed that with the increase of average current density，the cathodic polarization was enhanced，then the surface morphology of the coating changed as "hexagonal star-rock sugar-globular clusters" . The coating consisted of a fine equiaxed crystal nucleation layer and a continuous columnar crystal growth layer，and the thickness of the continuous layer decreased due to nodulation. The pulse frequency affected the ion mass transfer and subsequently the coating surface quality by regulating the pulse loading/termination time and the bilayer charging/discharging time. Too small pulse frequency led to concentration polarization，too high frequency would lead to the actual current close to DC，either of which led to the deterioration of the surface quality of the coating. A moderate pulse frequency allowed the active ions to be replenished timely and avoided concentration polarization，thus optimizing the surface quality of the coating. At a constant average current density，the peak current density during pulse loading could be influenced by adjusting the duty ratio，leading to different cathodic polarizations and ultimately affecting the coating surface quality. When the duty ratio was low，the peak current density was much higher than the cathodic limit current density which would rapidly trigger the concentration polarization，and when the duty ratio was high，the single pulse deposition time became longer，and the active ions were difficult to recover in time，which also caused the concentration polarization and led to the deterioration of the coating surface quality. When the duty ratio was moderate，the appropriate peak current density and deposition time could make the cathodic polarization moderate，and the active ions were replenished in time to optimize the coating surface quality. The microstructure of the coating was related to cathodic polarization. When electrochemical polarization or concentration polarization was not strong，the pulsed electrodeposited Nb coating grew in an upward growth mode with a typical columnar crystal structure，and the optimal growth crystal surface was （211）. When the deposition conditions corresponded to a significant increase in cathodic polarization，the optimal growth crystallographic of Nb coatings transitioned to （110） or （200）. The microhardness of the coating was little affected by the change of process parameters and was positively correlated with the content of oxygen impurities in the coating. When the cathodic polarization corresponding to the pulse electrodeposition condition was weak，no oxide was formed in the Nb coating，and the microhardness of the coating was between 260 and 300 kg·mm^-2. When the cathodic polarization corresponding to the pulse electrodeposition condition was strong，oxide impurities were formed in the Nb coating，which led to a significant increase in the microhardness of the coating，up to 927 kg·mm^-2. In all，the pulsed electrodeposition process affected the coating surface quality mainly by influencing the degree of cathodic polarization. Electrodeposition processes that resulted in higher cathodic current densities （higher average current densities or lower duty ratios） or longer continuous deposition times （higher/lower frequencies or higher duty ratios） all increased cathodic polarization and led to coating surface nodules. Using the optimized pulsed electrodeposition process （average current density of 10~50 mA·cm^-2，frequency of 0.5~25 Hz，and duty ratio of 50%），Nb coatings that were smooth，dense，with a typical columnar structure，with a preferred growth plane of （211），and with microhardness in the range of 260~300 kg·mm^-2，could be obtained.

High-strength and excellent-conductivity copper alloys are widely used in the field of rocket engine combustion chamber materials due to their excellent physical and mechanical properties. Among them，the Cu-Cr-Nb alloy is a kind of precipitation-strengthened copper alloy，such the strengthening effect attributes to the intermetallic compound Cr₂Nb. The alloy not only has good high-temperature stability，but also has advantages such as high temperature oxidation resistance，high strength at room temperature and high temperature，at the same time，it has the ability to resist creep and thermal corrosion，and has become a fourth-generation rocket engine combustion chamber wall material. Since Cr and Nb have infinite solubility in liquid copper but low solubility in solid copper，when Cu-Cr-Nb alloys are prepared by conventional casting metallurgical process，the incipient Cr₂Nb phase is preferentially generated during solidification，and the Cr₂Nb phase in the alloys prepared by conventional casting is coarse and cannot be removed by subsequent processing. In this paper，Cu-Cr-Nb alloys with different Cr and Nb contents （Cu-8Cr-4Nb，Cu-4Cr-2Nb，Cu-2Cr-1Nb，Cu-1Cr-0.5Nb，and Cu-0.8Cr-0.4Nb） were prepared by vacuum induction melting and water-cooled copper mold casting，and the effects of alloy composition on the as-cast microstructure and mechanical properties under sub-rapid solidification conditions was investigated. The principle of designing the composition of Cu-Cr-Nb alloy was that the atomic ratio of Cr to Nb was 2∶1. The ratio of 2∶1 fits the molecular composition of Cr₂Nb，too much Cr，Nb elements would cause elemental segregation，the formation of large-size Cr₂Nb，had formed hard inclusions，resulting in fracture. Sub-rapid solidification was a solidification process between near-equilibrium low-rate growth and away-from-equilibrium rapid growth with a cooling rate in the range of 10~1×10³ K·s⁻¹，which was a method of solidification that allows the alloy to grow at a faster growth rate at a larger supercooling degree. At higher cooling rates，the alloy solidified rapidly from the liquid state to form a supersaturated solid solution. This supersaturated solid solution was aged to obtain finer，more dispersed particles of the precipitated phase. The results showed that the microstructure of the cast Cu-Cr-Nb system alloy consisted mainly of α-Cu matrix，high melting point intermetallic compound Cr₂Nb and nonequilibrium Cu-Cr eutectic phase. As Cr and Nb content decreased，the primary Cr₂Nb phase in the alloy showed a uniform diffuse distribution，the morphology evolved from coarse rod-like to granular，the average size decreased from 13.3 to 3.9 μm，the area fraction decreased from 15.8% to 1.3%，and the eutectic phase gradually disappeared. Cu-8Cr-4Nb alloy contained a large amount of the large-size intermetallic compound Cr₂Nb. Its pinning on the grain boundaries played a hindering role to the dislocation motion during the deformation process，effectively hindering the dislocation motion within the crystal and pinning effect on the grain boundaries，leading to brittle fracture of the material，and the strength of its alloys was enhanced while the electrical conductivity and plasticity are minimized. As the number and size of primary Cr₂Nb phases decreased，the strength of the alloy tended to decrease，while plasticity and electrical conductivity gradually increased，and the fracture mechanism changed from brittle fracture to plastic fracture. Cr₂Nb strengthening phase was the main load-bearing phase of Cu-Cr-Nb system alloys，and the improvement of mechanical properties such as tensile strength and yield strength of the alloys mainly relied on the diffuse reinforcing effect of Cr₂Nb phase. In a comprehensive analysis，the best composition of Cu-Cr-Nb alloy prepared by sub-rapid solidification was Cu-1Cr-0.5Nb，when the tensile strength，yield strength and elongation reached the optimum of 225 MPa，110 MPa and 37.5%，respectively，and the electrical conductivity was 48.16%IACS.

With the continuous increase of freight volume in heavy railway，the demand for the corrosion resistance of railway freight car body materials has increased. Q450NQR1 and Q345NQR2 are the primary materials used in railway freight car bodies，however，through our investigations，it has been found that the amount of corrosion-induced damage in the actual use of these two materials remains unacceptably high. Therefore，in this paper，the corrosion behavior of Q450NQR1 and Q345NQR2 weathering steels was studied，using electrochemical workstation，cyclic immersion corrosion testing machine，scanning electron microscopy （SEM），X-ray diffraction （XRD），and electron probe microanalysis （EPMA），aiming to explore the reasons for the interaction between alloying elements that affect corrosion resistance and play a crucial role in enhancing the corrosion resistance of weathering steels. The electrochemical corrosion tests of the two weathering steels showed that Q345NQR2 had better electrochemical corrosion performance compared to Q450NQR1，due to the content of Cu，P，Cr and Ni in Q345NQR2 was higher than that in Q450NQR1. The corrosion behavior of Q450NQR1 and Q345NQR2 was also investigated after 72 h of accelerated corrosion in an industrial atmospheric environment，and the results showed that the weight loss rate of Q345NQR2 was 1.264 g·m⁻²·h⁻¹，higher than that of 1.139 g·m⁻²·h⁻¹ for Q450NQR1，indicating a poorer corrosion resistance，contrary to the results of electrochemical corrosion. The macroscopic morphology of the sample surface revealed a rougher rust layer for Q345NQR2 compared to Q450NQR1. SEM images of the surface morphology further revealed the presence of corrosion pits on the surface of Q345NQR2，while the rust layer surface of Q450NQR1 was smoother and denser. The corrosion products of both weathering steels were found to be γ-Fe₂O₃/Fe₃O₄，α-FeOOH and γ-FeOOH，and the protective corrosion product α-FeOOH accounting for a higher proportion （38%） on the surface of Q450NQR1 compared to Q345NQR2 （36.7%）. The integrity and continuity of the rust layer structure played an important role in resisting external corrosion，and improving the corrosion resistance of weathering steel. During the formation process of the rust layer，the structure of the rust layer was closely related to the distribution of alloy elements. Therefore，EPMA was then employed to observe the distribution of alloying elements at the interface of the rust layers for Q450NQR1 and Q345NQR2. In the rust layer of Q345NQR2，Cu，P，and Cr were found to be enriched to varying degrees，while the Ni was evenly distributed in both the matrix and rust layer，and with a higher content in the matrix. In the rust layer of Q450NQR1，Cu was clearly aggregated on the outer side of the outer rust layer，P showed a weak aggregation on the outer side of the outer rust layer，while Cr and Ni were evenly distributed in the matrix and the rust layer. The interaction of alloying elements Cu，P，Cr，and Ni played a crucial role in the structure of the generated rust layer. In the initial stage of corrosion，the surface of weathering steel would generate an outer rust layer with significant differences in morphology and density，due to the different enrichment states of Cu，P，Cr，and Ni elements. The effect of Cu-Ni on the densification of rust layer was stronger than that of P and Cr elements. If the generated outer rust layer developed into a porous and porous structure，the corrosion process entered the second stage，where the inner rust layer was generated by P-Cr interaction. The lower the density of the outer rust layer，the more intense the second stage of corrosion would be，and the thicker the generated inner rust layer would be. In addition to promoting the formation of a dense rust layer on weathering steel，P could also accelerate the corrosion of the steel substrate. Therefore，in the actual production process，appropriately reducing the content of P and increasing the content of Cu，Ni could effectively reduce the pores in the surface rust layer，thereby improving the corrosion resistance of weathering steel. To sum up，the actual corrosion resistance depended on the composition and structure of the rust layer. The greater the amount of α-FeOOH，the denser the rust layer on the surface of the material，leading to better corrosion resistance. Under the influence of Cu-P-Ni interactions，the outer rust layer of Q345NQR2 was loose and porous，whereas the outer rust layer of Q450NQR1 was continuous and dense. Meanwhile，the refinement effect of NiFe₂O₄ and FePO₄ on the rust layer effectively resisted the invasion of external corrosive agents. Under Cr-P interactions，the outer rust layer was continuously transformed into the inner rust layer，simultaneously，the uniform dissolution of the matrix was accelerated to form a dense inner rust layer. Consequently，the inner rust layer of Q345NQR2 was thicker than that of Q450NQR1. The dense inner rust layer formed by weathering steel played a significant role in resisting further invasion of corrosive agents. Under Cu-P-Cr-Ni interactions，Q450NQR1 exhibited worse electrochemical corrosion performance compared to Q345NQR2，yet displayed better performance in cyclic immersion corrosion than Q345NQR2.