CoCrFeNi high entropy alloy has become one of the most popular systems in the pursuit of high toughness parts research because of its excellent plastic deformation ability and high yield strength of a single stable facecentric cubic solid-solute structure. At the same time, selective laser melting technology has unparalleled advantages over traditional preparation methods due to its flexible forming size and ultra-fast heating and cooling rates. In this paper, the CoCrFeNi-X high-entropy alloy systems successfully created by the selective laser melting technology in recent years and the effects of tissue structure on mechanical properties for eight different alloy systems in terms of phase structure and tissue morphology were analyzed；the effects of the preparation process on forming density and mechanical properties for three CoCrFeNi-X high entropy alloys formed parts were examined；Finally, a detailed analysis of the current status of the two mainstream alloy systems, CoCrFeNi-Alx and CoCrFeNi-Mn, was done on the alloy composition design. The research and analysis are expected to provide some theoretical guidance for the experimental research and industrial application of preparing CoCrFeNi-X system high entropy alloys by selective laser melting technology.

The heat treatment process is important to improve the forming quality of laser cladding coatings. In this paper WC@Ni / Ni60A and rare earth mixed powder were used to investigate the influence of different heat treatment processes on the microhardness, microstructure, phase composition, and residual stress of the cladding layer and to explore the optimal annealing temperature. The results show that increasing heat treatment temperature decreases the coating microhardness. Higher microhardness of the coating can be obtained at 700 ℃. Samples with 1% La 2O3 and with 0.5% Y2O3 have a hardness of 64.9HRC and 65.3HRC, respectively. With the increase of heat treatment temperature, the wear volume becomes larger. At an annealing temperature of 700 ℃, the friction coeffi‐ cient of the sample is lower than that of the untreated one. The increase in heat treatment temperature helps to re‐ duce the residual stress. Considering the performance indexes, the optimal heat treatment scheme includes the fol‐ lowing parameters: the heating temperature is 700 ℃, the heating speed is 10 ℃/min, the insulation time is 60 min, and cooling mode is furnace cooling. The results provide a theoretical basis for improving coating quality through heat treatment.

Aluminum alloys, which have the advantages of low density, high specific strength, and good corrosion resistance, are widely used in aviation, shipbuilding, automobiles, and other fields. Selective laser melting forming (SLM) is a promising technology that can fabricate complex parts at one time. In this study, the friction and wear properties of Al-Cu-Mg alloy fabricated by selective laser melting (SLM) were studied and compared with those of a cast ZL205A alloy with a similar composition. The results show that the SLM process can refine the alloy grains, change the size and distribution of Al2Cu, and make the grains smaller and more uniform. Compared with the cast ZL205A alloy, the wear rate and friction coefficient of the SLM-fabricated Al-Cu-Mg alloy decreased in varying degrees. SLM-fabricated Al-Cu-Mg alloy has the best wear resistance in cross section, followed by longitudinal section, and cast ZL205A has the worst wear resistance. The wear mechanisms of SLM-fabricated Al-Cu-Mg alloy are different under varying loads: the wear mechanisms at low load are mainly abrasive, and a little adhesive and plastic extrusion wear; the wear mechanisms under medium load are abrasive, adhesive and oxidation wear; the wear mechanisms under high load are mainly a combination of delamination, adhesive and oxidation wear.

Preparation of composite stainless steel wick, as well as its maximum pore size, air permeability, permeability and liquid absorption performance were studied. The preparation process shows that the surface state of the inner wall of the stainless steel pipe is changed by lathe processing, and the composite stainless steel wick with good interface combination between stainless steel pipe and pore layer is obtained. The material performance test results show that the maximum pore size of the powder sintered porous layer in the composite stainless steel wick is concentrated between 9.5~10.2 μm, the air permeability is between 101~109 m³/（m²·kPa·h）, and the permeability is 1.14×10^-13~11.4×10^-13 m². The aspiration behavior of the composite stainless steel wick test results show that the composite stainless steel wick can lift the ethanol working fluid to a height of 11.0 cm within 15 minutes.

Aiming at the problem of WC sinking in preparing Ni/WC composite coating, the coating was fabricated by plasma transfer arc welding technology under the applied external magnetic field. The distribution of Ni/WC coating plus WC particles under the applied magnetic field was investigated, and the microstructure and properties of the coating were characterized by vickers durometer, SEM, OM and EDS. The results showed that WC was deposited near the coating fusion line when no magnetic field was applied, while WC particles were concentrated in the middle area of the coating when the magnetic field was applied, with a distance of 420 μm from the bottom of the area to the coating fusion line. The hardness of the coating fluctuated with the applied magnetic field. The maximum value of the hardness was 1400HV without external magnetic field, and it was 1450HV with external magnetic field. In the experiment, WC particles almost did not melt and the particle morphology remained intact. The magnetic field refines the coating structure, promotes the generation of hard phase and improves the hardness of the coating. The external magnetic field solves the problem of WC subsidence and could be adjusted according to the engineering requirements.

The low oxygen MHC alloy plates were prepared by powder metallurgy and hot rolling method. The microstructure, and mechanical properties of low oxygen MHC alloy rolled plates were studied by chemical analysis, metallographic analysis, hardness test, and tensile mechanical property test. The results show that molybdenum powder reduction, and vacuum sintering, the oxygen content in the alloy can be effectively reduced by adjusting C/Hf atomic ratio. The comparison of microstructure analysis and mechanical property test results of samples annealed at different temperatures, the recovery stage of the alloy is below 1 300 ℃. With the increase of annealing temperature, recrystallization begins at 1 300 ℃, the strength and hardness gradually decrease, and the plasticity increases. The recrystallization is completed at 1 600 ℃. The low oxygen MHC alloy with complete recrystallization has excellent plasticity.

In recent years, the demand for high-strength-high-plasticity metal materials in the fields of automobiles and ships has been increasing. In order to obtain high-strength-high-plasticity metal materials, powder metallurgy technology plays an increasingly important role. In this study, the mixed metal powders of martensitic steel and austenitic steel with a mass ratio of 2:1 were sintered by spark plasma sintering (SPS), and the austenite phase was uniformly distributed in the martensite phase. The density of the sample is as high as 95.5%, and through the subsequent hot rolling treatment, the sintering quality of the composite steel is improved, and the density is increased to 98.9%.The yield strength, tensile strength, uniform elongation and total elongation of the clad steel after hot rolling are 960 MPa, 1 529 MPa, 6.7% and 6.7%, respectively. On the basis of hot rolling, cold rolling + short-time high temperature tempering treatment is introduced, and the performance of powder metallurgy composite steel is further improved. Among them, the clad steel cold-rolled at 30%-500℃ and tempered for 5 min has yield strength, tensile strength, uniform elongation and total elongation of 1 899 MPa, 1 964 MPa, 9.2% and 10.0%, respectively.

Metal powder injection molding technology is an advanced processing method of titanium alloy. The quality of injection molding products is closely related to the properties of feedstock, uniformity and rheological properties are important indexes to feedstock. In this paper, the effect of spherical powder size distribution on the properties of TC4 titanium alloy feedstock was studied by microscopic morphology analysis, uniformity and rheological properties analysis. The results show that the loading of feedstock can be effectively enhanced by increasing the distribution width of spherical powder size. Reducing distribution width of powder size is condu‐ cive to improving the uniformity of feedstock. Increasing the spherical particle size and reducing distribution width of powder size are two approaches to enhance the fluidity of feedstock.

Compared with laser and e-beam based additive manufacturing technologies, the combined 3D printing and sintering process is cheaper, but the exploration of the process parameters in the sintering stage is not comprehensive and in-depth enough. Therefore, the experiment uses screw-based 3D printing technology to prepare 17-4PH stainless steel samples, to explore the influence law of sintering process parameters (sintering temperature, heating rate and holding time) on the properties of 17-4PH stainless steel, including porosity and tensile property measurements, and to investigate the influence law of the sintering process parameters on the pore structure, microstructure and fracture morphology. The changes in the mechanical properties of the sintered samples were elaborated through the changes in the pore structure, microstructure and fracture morphology. The results show that the mechanical properties of the sintered samples are best when the sintered samples are heated up to 1 360 ℃ for 1 h at a rate of 4 ℃/min, with a yield strength of 518 MPa and a tensile strength of 693 MPa.

The influence of sample thickness, heating temperature, and carbon spray layer on the thermal diffusion coefficient of beryllium material was studied. The results indicate that the thermal diffusion coefficient on the side of the sample with a thickness ranging from 2 mm to 6 mm tends to be consistent. The standard deviation of multiple tests with a thickness of about 2 mm is the smallest, and the test results are more accurate. It is recommended to use this thickness as the sample thickness for measuring the thermal diffusion coefficient of beryllium materials. The beryllium coefficient gradually decreased with the heating temperature by 77.9% when the temperature increased from 25 ℃ to 900 ℃. Under different cases of carbon spray layer, the thermal diffusivity tested is significantly different, and the thermal diffusive coefficient measured on the test sample surface is coated with thin and uniform graphite.

Platinum rhodium alloy (PtRh20) powder was prepared in pure aqueous medium by spark plasma. The impurity content, surface morphology, composition and particle size distribution of the powder were analyzed by ICP, SEM and laser particle size analyzer. The results show that the efficiency of PtRh20 alloy powder prepared by electrospark plasma erosion method is up to 1 000 g/h, and the purity of the powder is high. It is composed of high spherical particles and floccules with the same composition. The particle size of the powder is basically between 5-60 μm, and the average particle size is 25 μm.

In high-voltage power transmission systems, W-Cu electrical contact alloys are subjected to complex environments involving high-temperature arc ablation, SF6 gas erosion, and mechanical wear, necessitating a combination of high conductivity, strength-toughness, and corrosion resistance. This paper systematically reviews the microstructure regulation mechanisms of preparation technologies such as electroless plating, melt infiltration, spark plasma sintering (SPS), mechanical alloying, and microwave sintering, and discusses the influence of different processes on the interfacial bonding characteristics of W/Cu. The study comprehensively analyzes The effects of metal particles, ceramic phases, and fiber reinforcements in enhancing arc erosion resistance through mechanisms such as grain refinement strengthening and second-phase strengthening, while summarizing the synergistic regulation mechanisms of reinforcement phase morphology distribution and interfacial reactions on the material's overall performance. Current research demonstrates that multicomponent composite reinforcement systems effectively mitigate the conductivity-mechanical property trade-off. For instance, microwave-sintered materials with nano dual-phase reinforcement maintain high electrical conductivity even under significant hardness improvement. Future efforts should focus on developing core-shell structured nano-reinforcements, external field-assisted sintering technologies, machine learning design platforms, and full-lifecycle performance evaluation systems to address the challenge of conductivity-strength synergy. With the integration of multidisciplinary approaches, W-Cu alloys are expected to deliver next-generation high-performance contact material solutions for smart grids and extreme-environment electrical devices.

Magnesium alloys are the lightest metal structural materials, characterized by low density, high specific strength and stiffness, excellent damping，shock absorption properties, and good biodegradability. Traditional manufacturing methods of magnesium alloys, such as casting and extrusion, find it challenging to produce complex geometries in a single step. Cast magnesium alloys often suffer from coarse grains and poor mechanical properties due to low cooling rates, while extruded magnesium alloys are prone to defects like oxidation inclusions during forming. In contrast, additive manufacturing (AM) technology offers the advantage of rapid integrated forming and has gradually been applied to the production of magnesium alloys. Currently, the main AM technologies for magnesium alloys include Laser Powder Bed Fusion (LPBF), Wire Arc Additive Manufacturing (WAAM), Additive Friction Stir Deposition (AFSD), and Binder Jetting (BJ). The current status of additive manufacturing of magnesium alloys, analyzing of the forming principles, characteristics, and specific alloy properties of these four AM technologies were reviewed. The research status and existing problems of these four additive manufacturing techniques for magnesium alloys were discussed, their advantages and disadvantages were summarized, and aims to promote the research progress of magnesium alloy additive manufacturing technology.

The development and application of hot extrusion process for P/M superalloys in Europe and US were summarized. The research progress of hot extrusion process for P/M superalloys in China was described. The selection principles of extrusion process parameters for René 95, René 88DT and FGH4096 alloys were introduced. The influence of extrusion process parameters (extrusion ratio, extrusion speed, extrusion temperature, etc.) on the extrusion forming, microstructure and properties of P/M superalloys was emphatically expounded. The evolution behavior of non-metallic inclusions in P/M superalloys during hot extrusion was clarified.

In this paper，micro-nano Fe-Co-Cu prealloyed powder was prepared by mechanical-chemical alloying method. The effect of ball milling time，reduction time and temperature on the particle size and reduction rate of the reduced powder were investigated. The results show that the precursor powder has a narrow particle size distribution and uniform composition under the condition of ball milling time of 2 h and grinding aid content of 100 mL by mechanical- chemical alloying method. When the precursor is reduced at 650 ℃×60 min under hydrogen atmosphere，a micro-nano Fe-Co-Cu prealloyed powder with uniform particle size and low oxygen content can be obtained.

Laser Powder Bed Fusion (LPBF) technology has significant advantages in rapid prototyping of complex structures and is widely used in many fields. However, the complex process characteristics of LPBF make its formed parts prone to pore defects such as porosity and lack of fusion. Laser powder bed melting experiments and numerical simulations were conducted on Inconel 718 alloy, which is widely used in aerospace, shipbuilding, and energy fields. This article combined experimental forming and numerical simulation methods to conduct research. The discrete element method was used to establish a random powder bed model, and the dynamic flow evolution process of the LPBF melt pool was simulated through computational fluid dynamics methods. This article analyzed the influence of key process parameters such as laser power, scanning spacing, and scanning speed on forming defects. Combining experimental detection and discrete element simulation, the mechanism of pore defects such as porosity and lack of fusion was discussed, and the optimal process parameter data was obtained through analysis.When the laser scanning spacing decreases, the porosity of the longitudinal section of the sample decreases; When the laser scanning speed increases, the number of non fusion defects at the edges of the sample increases; When the laser power increases, the number of pores inside the sample significantly decreases, and irregular non fusion defects appear at the edge of the melt. At a laser scanning interval of 80 μm. When th e laser scanning speed is 500 mm/s and the laser power is 200 W, a sample with appropriate melt width, fewer forming defects, and lower porosity can be obtained.

Titanium and its alloys are widely used in aerospace, automobile and ship, petrochemical industry, biological medicine and other fields because of their low density, high strength, good corrosion resistance and good biocompatibility. The article mainly aims at the preparation technology of powder metallurgy of titanium and titanium alloys, current situation are introduced. Powder manufacturing and densification at home and abroad are introduced. It is pointed out that the key for the future development of powder metallurgy titanium alloys is the preparation of low clearance element fine titanium powder, large size green and high performance sintered preform.

In this paper，93W-5Ni-2Fe tungsten heavy alloy prepared by powder metallurgy method were tested at 1 000，1 100，1 200，1 300 and 1 400 ℃，the high temperature mechanical properties were investigated respectively. The fracture analysis and the developing principles of fracture mechanism were studied. The results show when the elevating temperature is 1 000- 1 400 ℃ ，mechanical properties of 93W- 5Ni- 2Fe alloy，such as tensile strength，elongation，reduction of area and Young's module get worsedramatically. Material becomes brittle，transgranular fracturecan be hardly found，binder phase tear and inter-facial fracture between tungsten grain and binder phases are domestic fracture mode.

The effect of deformation on the depth of the surface densification layer of powder metallurgical Fe-CuMn-Mo-C materials was investigated using plastic densification techniques. By increasing the amount of deforma‐ tion, the pores on the surface of the parts were reduced and the surface densification depth and hardness were im‐ proved. The experimental results show that the surface of the powder metallurgy parts prepared by extrusion densi‐ fication technique can form a uniform densification layer and the surface hardness of the parts can be improved. When the finished deformation is increased to 0.4 mm and 0.6 mm, a dense layer of about 0.25-0.4 mm is formed on the surface of the powder metallurgical parts with a specimen density of 6.8 and 7.0 g/cm3. The depth and hard‐ ness of the surface dense layer increase with the amount of deformation, indicating that the amount of deformation is one of the most important factors influencing the surface densification effect of the parts.

Titanium alloy has the characteristics of high strength, lightweight, and high temperature resistance, making it a promising aerospace structural material. The traditional mechanical manufacturing process is difficult and costly, which limits the application of titanium alloys. Additive Manufacturing (AM), as an emerging advanced manufacturing technology, can produce metal components with high three-dimensional accuracy through layer by layer machining, providing near net shape machining for titanium alloys. This article first introduces the preparation technology of spherical titanium alloy powder, including Plasma Rotating Electrode Atomization Process (PREP), Electrode Induction Gas Atomization (EIGA), Plasma Atomization (PA), and Plasma Spheroidization (PS). The preparation technology and advantages and disadvantages of four spherical titanium alloy powders are compared, as well as their applications in aviation additive manufacturing, including Laser Selective Melting (SLM). The application characteristics and development trends of different titanium alloy powder preparation technologies in aviation additive manufacturing are summarized, such as Electron Beam Selective Melting (EBSM) and Laser Melting Deposition (LMD). It is pointed out that the key to the future development of spherical titanium alloy additive manufacturing is the preparation of low gap titanium powder. High precision, high efficiency and large scale of additive manufacturing equipment will be the future development trend.

The effects of 1% TiB₂ particles as reinforcing phase on the microstructure and properties of Al-Zn-Mg-Cu alloy were studied. Al-6Zn-3Mg-Cu aluminum alloy and TiB₂/Al-6Zn-3Mg-Cu composite material were prepared using Spark Plasma Sintering (SPS) technology. The desired samples were obtained after hot forging, hot extrusion, and T6 heat treatment, followed by the study and analysis of the samples' microstructure and mechanical properties. The results indicate that there is no macroscopic segregation of alloy elements, and TiB₂ particles are uniformly distributed in the aluminum alloy matrix. The grain size of the aluminum-based composite material modified with TiB₂ is refined, the defects and pore aggregation in the structure are reduced, and the TiB₂ promotes the uniform distribution of MgZn₂ precipitation phase in the matrix. Due to the combined effects of grain refinement, improvement of microstructure, age-hardening precipitation of MgZn₂, and reinforcement from TiB₂ particles, the TiB₂/Al-6Zn-3Mg-Cu composite material achieves ultimate tensile strength, yield strength, and elongation of 539 MPa, 495 MPa, and 10.3%, respectively, showing improvements over the Al-6Zn-3Mg-Cu alloy in all three aspects.

Inconel738 powder for laser cladding was prepared using plasma rotating electrode method. Three factor and four level orthogonal experiments were conducted on the powder preparation process, and powder detection, morphology, and microstructure observation were carried out on the obtained process.The results show that the Inconel738 powder prepared by plasma rotating electrode method at a speed of 22 000 r/min, a current intensity of 650 A, and a feed rate of 1.3 mm/s could achieve a powder yield of 91.0%, The powder has a flowability of 10.7 s/50 g and a loose density of 4.78 g/cm³ the oxygen content of 0.68×10^-4,the sphericity of 92%. The powder has good sphericity, smooth surface, almost no hollow powder, and a dendritic structure inside and outside, which can be used for laser cladding.

The experiment selected water atomization, gas atomization and centrifugal atomization to prepare 316L stainless steel powder, the magnetic conductivity of different kinds of powder grading was tested, the microstructure was characterized by SEM, EDS and XRD, and the effect of the preparation method on the magnetic conductivity of 316L stainless steel powder and the causes were investigated. The study shows that the 316L stainless steel powders prepared by atomization have magnetic conductivity, and the reason for magnetic conductivity is the existence of high temperature δ ferrite phase in the powder. The finer the particle size of the powder, the faster the cooling speed, the more cytocrystalline content, the higher the δ ferrite content, and the stronger the corresponding magnetic conductivity. The magnetic permeability of the powder prepared by water atomization is the highest, of the centrifugal atomization is centered, and of the powder prepared by gas atomization is slightly lower. The cooling capacity of centrifugal atomization is higher than gas atomization.

HSS and tool steels perform specially with their high mechanical and thermal properties such as high strength and toughness, high hardness, high wear resistance, and good heat resistance, which are widely used in in‐ dustries such as metalworking, plastic injection molding, and automotive manufacturing, etc. Conventionally, they are prepared by traditional casting and forging process, which always introduce compositional segregation and coarse carbides in their microstructure. These micro defects are difficult to eliminate through conventional process‐ ing methods such as forging, leading to the deterioration in material properties. The powder metallurgy process pro‐ vides an uniform microstructure, fine dispersive carbides, and high alloy composition, which allows for the manu‐ facturing of complex shapes and structures of the final products. Through this approach, the tool and die products have the advantages of higher performance, higher precision, and longer life, and have important applications pros‐ pects in the high-end manufacturing industry. In this work, a comprehensive review of the production technologies and applications of powder metallurgy HSS and tool steels are provided. Besides, the technological innovations in the industrial production, the manufacture methods, and the microstructural properties of powder metallurgy HSS and tool steels are discussed in details. Furthermore, the classifications and applications of these materials, offering an outlook on the future development trends in powder metallurgy HSS and tool steels are summarized.

Cu/Al laminated composites are more and more widely used because of their high cost-effective synergistic effect. However, the interface structure, microstructure of copper layer and aluminum layer of Cu/Al composites prepared by different process methods are different, and the mechanical properties are different. The difference in interface bonding characteristics leads to macroscopic quality problems such as dislocation, delamination, and copper layer surface tearing during deep processing, which seriously restricts its application in high-end fields. In this paper, the research status of atomic scale of copper-aluminum laminated composites is introduced. The research progress of molecular dynamics simulation on the interface layer structure, diffusion and solidification, the correlation between heterogeneous interface characteristics and mechanical properties of copper-aluminum laminated composites is reviewed. The advantages and disadvantages of different potential functions in molecular dynamics simulation of copper-aluminum laminated composites are analyzed. It is proposed that accurate model, reasonable force field and accurate parameters are the three basic criteria for material atomic scale simulation, which provides a reference for the study of atomic scale of metal laminated composites.

Copper and its alloys are renowned for their excellent thermal and electrical conductivity, and various other beneficial properties. Integrating these materials with the design flexibility offered by 3D printing technology can significantly improve the efficiency of heat exchange and current transmission. A comprehensive overview of recent advancements in 3D-printed copper and copper alloys was presented. It also provides a detailed comparison of the advantages and disadvantages of different forming methods, along with an analysis of existing challenges. Numerous studies indicate that achieving controlled shape and performance in 3D-printed components necessitates the integrated control and optimization of materials, structures, processes, and overall performance. However, the application of 3D printing technology to produce copper and its alloys still faces several hurdles. The low absorption and high reflectivity of copper towards laser energy complicate achieving desired structures through the selective laser melting and laser melting deposition processes. Additionally, the surface quality of components produced via the electron beam selective melting method is often suboptimal for precision manufacturing. Moreover, the binder jetting technology necessitates post-forming heat treatment, which can result in shrinkage and deformation issues. The potential applications for 3D-printed copper and copper alloys were explored, highlighting their contributions to the ongoing evolution and innovation within the advanced manufacturing sector.

Mass production of high grade stainless steel powder for MIM (metal injection molding) was produced by combined atomization technology of water and gas. The design of nozzle, optimization of refractories, control of powder oxygen content and research on powder treatment technology were discussed in the present work. In comparison with the common stainless steel powder 316L and 17-4PH, the properties of produced powder have reached the advanced level of international similar products. Industrial scale production of 500 Kg is realized, and the production capacity of special alloy powder can reach 10 thousand tons per year.

Using metallographic microscope, scanning electron microscope, oxygen-nitrogen analyzer, laser particle size analyzer, and X-ray diffraction analyzer, the characteristics of M50NiL powder prepared by plasma rotating electrode process （PREP), including the microstructure and phase composite, nitrogen-oxygen content, particle size distribution, and flowability were characterized. The results indicate that the powder has a relatively narrow particle size range, primarily distributed between 30-53 μm, with a unimodal distribution and a Gaussian distribution curve. The average particle size is 45.21 μm. The chemical composition of the powder is uniform, with high purity and no other impurities. Metal powder has low nitrogen-oxygen content with the below 0.024% of the oxygen and the below 0.025% of the nitrogen. The M50NiL powder with different particle sizes are primarily composed of α phase. The solidification structure varies with the change of the particle size: 15-53 μm consists of fine cellular and dendritic structures, whereas 53-150 μm is dendritic, and >150 μm is characterized by coarse equiaxed crystal structures. M50NiL powder has excellent physical properties and meets the technical requirements of powder bed fusion additive manufacturing.

Metal injection molding (MIM) technology was adopted to prepare tungsten-copper alloy. Particle size and particle shape of the selected copper powders was quantitatively characterized by image analysis technology. The influence of the copper powders on the microstructure and properties of MIM tungsten-copper alloy was investigated in detail. By comparing，the characteristic parameters such as particle size, particle size distribution width, aspect ratio, roughness, outgrow and bluntness of the copper powders, the particle sizes of the crushed copper (CCu) powders and the water atomized copper (WCu) powders were much smaller than that of the reduced copper (RCu) powders, however the CCu powders exhibited wider particle size distribution and better regularity, surface smoothness and dispersion microstructure than the WCu powders and RCu powders. With tungsten powder blended with the CCu powders as raw materials, the tungsten-copper green parts were prepared by MIM showed high density and few defects. After sintering, the tungsten-copper alloy has the best microstructure and properties, with a density of 96.2%, a hardness of 235 HV, a bending strength of 1 200 MPa, a thermal conductivity of 128 W/(m·K) and an electrical conductivity of 30%IACS.

Cu-Sn powders were prepared by pre-mix and pre-alloy process, the microstructure and phase changes of Cu-Sn alloy were studied after sintering, and the sintering properties of Cu-Sn powders prepared by these two methods were tested and compared. The experimental results show that the microstructure of pre-mixing CuSn10 and CuSn20 is composed of α phase and α + δ eutectic tissue after sintering, while that of pre-alloy CuSn10 is α phase. After sintering, the pre-mixed Cu-Sn green compacts expand, on the contrary the pre-alloyed green com‐ pacts shrinkage. In addition, the strength, oil content and effective oil content of the pre-alloyed Cu-Sn parts are higher than those prepared by the pre-mixing method.

The surface of sintered Ti80 alloy was strengthened by surface ultrasonic rolling (USRP) technology, and the microstructure and properties of Ti80 alloy before and after rolling were analyzed by optical microscope (OM) and scanning electron microscope (SEM). The results show that the surface strengthening effect of the sample is the best when the rolling amplitude is 10 μm. The densification effect of the sample after rolling is remarkable. The surface hardness is increased by 18.5% and the surface roughness is reduced by 86%. The tensile strength and yield strength of rolled Ti80 alloy are 992 MPa and 815 MPa, respectively, which are 15.2% and 1.3% higher than those of sintered samples, and the elongation is increased from 1.7% to 2.6%. After soaking in 4 mol/L hydrochloric acid solution for eight days, the weight loss rates of sintered and rolled titanium alloys were 20.6 mg/cm² and 10.6 mg/cm², respectively, and the weight loss rate was reduced by 48.5%, which effectively improved the corrosion resistance of Ti80 alloy.

Modifications of zero-valent iron (ZVI) and its composites are presented, including cladding, loading, bimetallic, and vulcanisation. The mechanism of zero-valent iron treatment of wastewater, and the modification and application of its composites are discussed, and the problems existing in the application are analysed. The ZVI composites prepared by various modification methods can not only slow down the agglomeration of ZVI, increase the surface active area, but also can improve the treatment effect and stability of target pollutants. The stability of ZVI-modified materials and the synergistic solution of water pollution problems with microorganisms are proposed to be one of the key contents of future research.

Because of its high hardness, high strength, good plasticity and excellent heat shock resistance and creep resistance, rhenium metal has been widely used in aerospace nuclear industry, catalysis field, electronics field, biomedicine and other high-tech fields. In this paper, the preparation methods of rhenium powder and rhenium products are reviewed, among which the hydrogen reduction method is the most popular. The preparation of rhenium powder is developing in the direction of increasing the purity of rhenium powder. The mature preparation methods of rhenium products include powder metallurgy, electron beam melting and chemical vapor deposition. The production cost of powder metallurgy is low, but the production of complex components is difficult. The purity of the product prepared by electron beam melting is high, but the cost is high and the production of complex components is difficult. Chemical vapor deposition method has high purity and can prepare complex components. It is often used for the preparation of thin film materials, but the cost is high. The three methods are relatively mature, and all have certain industrial production capacity. On this basis, the mechanical properties and creep properties of rhenium prepared by different methods are compared. It is concluded that rhenium prepared by hot isostatic pressing and chemical vapor deposition has better properties. However, hot isostatic pressing method has not been industrialized because of its high cost. Domestic research institutions also need to further explore advanced preparation technology, in-depth study of rhenium deformation mechanism, and explore new application fields.

Aluminum powder is the most commonly used metal fuel in the explosives and propellants industry. How to make aluminum powder react as completely as possible in explosives and propellants has always been a difficult problem to solve. The combustion-assisted materials and technologies for aluminum powder are systematically reviewed and the different mechanism of promoting the combustion of aluminum powder is analyzed in this paper. Ammonium perchlorate(AP), fluorine-containing materials, nitro-containing compounds, azide-based materials, etc. have significant auxiliary effects on the oxidation of aluminum powder, and the aluminum-containing composites prepared by self-assembly process can help aluminum powder react completely more effectively.

In this study, the Fe-Al2O3 composite was prepared by carbothermal reduction method with Bayan Obo iron concentrate as main raw materials, meanwhile, the activated carbon was added as reducing agent. The effects of different amounts of reductants on the reduction process, microstructure and properties of composites were stud‐ ied. The results of XRD show that sample C1 is mainly composed of Al2O3, Fe, spinel and a small amount of iron oxide due to low reducing agent content. The diffraction peaks of spinel and iron oxide disappear with the increase of reducing agent dosage. Furthermore, there is a small amount of anorthite contained in the samples C1-C4, which gradually decreased with the increase of reducing agent dosage. SEM analysis shows that the metal phases are uni‐ formly distributed in the alumina matrix in granular form, and a small amount of glass phases exist at the grain boundary of alumina. Fracture mechanism analysis shows that the metal phase absorbs energy through plastic de‐ formation to improve the mechanical properties of the composites. The optimal properties of the sample are as follows: density of 4.12 g/cm3, porosity of 0.62%, linear shrinkage of 17.55%, bending strength of 308 MPa, hardness of 13.02 GPa, acid resistance of 93.55%, alkali resistance of 98.85%. This study provides a low-cost and cleaning process for the preparation of high performance composite materials from natural minerals.

With the rapid development of science and technology,the demand for high temperature solid self-lubricating composite materials in aerospace,metal forming,electric power and other industrial fields is increasing year by year.High temperature solid self-lubricating composite materials have become a research hotspot in the field of lubrication. In this paper, the research status of high temperature solid lubricants,high temperature solid self-lubricanting composite materials and its preparation technology in recent years were mainly reviewed, and the design concepts for new high temperature solid self-lubricating composite materials were summarized.

W-Cu composites is a structural and functional integrated material composed of W and Cu, exhibiting exceptional properties such as high hardness, strength, thermal stability, wear resistance, low coefficient of thermal expansion, good ablative resistance and conductivity. It finds extensive applications in electronic, electrical, aerospace and military industries. However, commercial W-Cu composites prepared through high temperature infiltration or liquid phase sintering often possess coarse structures with inferior mechanical properties. As China's industrial modernization progresses rapidly, higher requirements are also put forward for the comprehensive properties of W-Cu composites. As a result, the preparation technology of W-Cu powder and blocks has greatly accelerated the development of W-Cu composites in recent years. This review summarizes the mechanisms and characteristics of different forming technologies and powder preparation techniques for W-Cu composites, along with an analysis of their microstructure and properties. Finally, future trends for the development of W-Cu composites are discussed.

Powder metallurgy technology is a scientific technology manufacturing metal powders, alloy powders, non-metallic powders, compound powders, or materials or products made from these powders through forming and sintering. As the metal powder in the preparation process is easy to adsorb oxygen and oxidation, in the sintering process is not easy to fully deoxidise, and with the development and use of alloying elements, chemically active alloying elements are easy to combine with oxygen elements, increasing the difficulty of deoxidisation, so that powder metallurgy materials are prone to oxygen content exceeding the standard, which seriously affects the performance of powder metallurgy materials. This paper discusses the influence of oxygen content on the preparation process and mechanical properties of various metals and alloys, and introduces the methods of controlling the oxygen content of some metals in the powder metallurgy process. It focuses on the research progress of oxygen content control of iron-based powder metallurgical materials, titanium and titanium alloy powder metallurgical materials, copper alloys, refractory metal tungsten and molybdenum powder metallurgical materials, and summarises the current status of the research and looks forward to the development trend of its future.

A TiC high manganese steel-bonded carbide with 0.1% boron addition was fabricated by powder metallurgy techiniques using TiC as hard phase and Fe, Ni, Mo, Mn, graphite C raw powders as the binder, and effects of sintering temperature on the microstructure and properties of the alloys were carried out. Microstructure observation shows that the structure of the alloy consists of black core-gray rim ceramic particles and white metallic binder, while, the ceramic particles grow gradually and its distribution become evenly with the temperature increase. The relative density of the alloy increases firstly and then decreases with the temperature increase, subsequently, the relative density of the alloy increases monotonously with the temperature increase and reaches the maximum value 98.29%. Mechanical properties results show that the hardness, transverse rupture strength (TRS) (in the as-sintered state and heat treatment state) and impact energy (IE) of the alloy increased monotonously with the temperature increase, also, reach the maximum value 63.8HRC, 1 993 MPa/1 425 MPa and 9.3 J/cm². The alloy densifies singnificantly when sintered from 1 320 ℃to 1 340 ℃, then, the hardness, TRS and IE of the alloy increases obviously. Subsequently, the increase rate of the hardness, TRS and IE of the alloy slow down which indicates the distinct role of B element in promoting densification. Boron element begins to volatilize and is exhausted completely at 1 420 ℃.The experimental alloy with B addition and the high manganese steel matrix are cast into a whole part, no obvious defects as cracks, impurities and pores are observed between the interfaces showing excellent interface bonding state and prospective long service life.

Using injection molding technology to produce near-net shaped Al₂O₃ ceramics can overcome the cutting difficulties caused by the high hardness of the ceramics. However, the commonly used paraffin based binders for injection molding have some deficiencies such as volatile paraffin components and easy phase separation during the injection process. Al₂O₃ powder with D₅₀ of 1.345 µm was injection molded using a new microcrystalline wax based binder. Effects of the injection parameters on the green density, the debinding ways and debinding temperature on the debinding rate, and the sintering temperature on the microstructure and property of the sintered Al₂O₃ ceramics were investigated. The results show that defect free injection green bodies can be obtained with injection temperature of 145 ℃, injection pressure of 7 MPa, holding pressure of 8 MPa, and mold temperature of 25 ℃. After debinding at 50 ℃ in trichloroethylene for 10 h and thermal debinding, the brown bodies are sintered at 1 550 ℃ for 4 h and the sintered samples with a relative density above 97%, a volume shrinkage rate of 45.5%, a microhardness over 15 GPa, a bending strength of 290 MPa can be obtained.