Aluminum nitride ( AlN ) has become a key material in the field of electronic packaging and thermal management due to its excellent thermal conductivity, insulation and thermal expansion coefficient matching with silicon. However, AlN powder is easily hydrolyzed with water or in a humid environment to form aluminum hydroxide (Al(OH)₃) or hydroxyl alumina ( AlOOH ), resulting in the loss of nitrogen content and the increase of oxygen content, which reduces the thermal conductivity of subsequent ceramics and thermal interface material, hindering the industrial application. In this paper, the hydrolysis mechanism of AlN powder is systematically reviewed, and the regulation of various factors on the hydrolysis behavior is clarified. The surface modification technology of aluminum nitride powder is reviewed. Finally, the problems existing in the current research are pointed out, and the future development direction is prospected, which provides theoretical support and technical reference for the efficient application of AlN powder in the field of electronic devices.

Al_xCu_1-xCoFeNi high entropy alloys (x=0.25, 0.5, and 0.75) were prepared using a combination of mechanical alloying and spark plasma sintering methods. The phase composition, microstructure, and mechanical properties of the high entropy alloy powder and sintered specimens at different stoichiometric ratios were studied. The results show that the sintered Al_xCu_1-xCoFeNi high entropy alloy with a ball milling time of 64 hours forms a single face centered cubic solid solution when x=0.25 and 0.5, while the high entropy alloy forms a face centered cubic and body centered cubic solid solution structure when x=0.75. At x=0.25, 0.5, and 0.75, the densities of the sintered Al_xCu_1-xCoFeNi high entropy alloy specimens are 98.3%, 95.8%, and 97.7%, respectively. At x=0.25 and 0.5, there is segregation of Al and Cu elements in the Al_xCu_1-xCoFeNi high entropy alloy, while at x=0.75, there is segregation of Al elements and no obvious segregation of Cu elements in the high entropy alloy. As the value of x increases from 0.25 to 0.75, the yield strength, fracture strength, and hardness of Al_xCu_1-xCoFeNi high entropy alloy gradually increase, while the compressive strain gradually decreases. Compared with cast AlCuCoFeNi high entropy alloy, the yield strength, fracture strength, compressive strain, and hardness of high entropy alloy are higher at x=0.25.

Binder jet 3D printing (BJ3DP) is a non-melting, high-efficiency, and cost-effective metal additive manufacturing technology. In recent years, it has shown great potential in producing complex structures, large-sized parts, and high-precision components. Compared with laser melting techniques, BJ3DP offers several advantages, such as broad material compatibility, low processing temperature, and the absence of residual stress. These features make it particularly suitable for heat-sensitive or easily oxidized metals. This paper reviews the key factors affecting the quality of metal parts produced by BJ3DP, including powder characteristics, printing parameters, and debinding/sintering processes. It focuses on the phase evolution, microstructure, and mechanical properties of various alloy systems, such as iron-based, nickel-based, magnesium-based, aluminum-based, and high-entropy alloys, etc. Finally, current challenges and future development trends were briefly outlined.

Additive manufacturing is an emerging material forming technology, whose shaping process is a typical non-equilibrium solidification process, involving complex physical phenomena such as temperature, thermodynamics, and phase transitions. It is difficult to measure and analyze the changes in physical quantities during the additive manufacturing process using traditional methods. Applying finite element numerical simulation technology to additive manufacturing can effectively calculate and predict the processing and outcomes, enhancing the efficiency of research and development in additive manufacturing and reducing costs. This paper provides a comprehensive review from three aspects: the finite element numerical simulation method, the introduction of finite element numerical simulation software, and their current applications in the field of additive manufacturing. It analyzes the advantages and limitations of finite element numerical simulation technology in the additive manufacturing field and offers a perspective on future development trends.

As an economic technology with the advantages of powder metallurgy and precision hot die forging, powder forging is a near-net-shape manufacturing technology, which produces parts with high precision and excellent mechanical properties by forging the preformed sintered compact. In this study, we provide a strategy to study the powder forging process as well as the mechanical properties of aluminum alloys using 6061 as an example. The constitutive equations and thermal processing maps of the sintered 6061 aluminum alloy are established through the thermal simulation, and on the basis of thermal analyses, the 6061 aluminum alloy is fabricated via powder metallurgy followed by precision hot die forging. Investigation on the microstructure and mechanical properties of as-sintered and as-forged aluminum alloys before and after T6 heat treatment are also carried out. The results show that the sintered 6061 aluminum alloy without instability during deformation in the range of 425-500 ℃/0.01-1 s^-1, indicating its excellent hot workability. Compared with the as-sintered alloys, the average grain size of as-forged alloys decreased from 12.3 μm to 9.6 μm, which enabled a uniform distribution of alloying elements. As a result, the density, hardness, yield strength and tensile strength reach 99.71%, HV64.7, 129 MPa and 220 MPa, respectively. In particular, it is noted that the as-forged alloy experienced a 138% increase in its elongation, achieving 29.6%. After T6 heat treatment, the as-forged alloys exhibit a hardness of HV135.2, a yield strength of 301 MPa, a tensile strength of 308 MPa and an elongation of 12%, and the dominant strengthening phases are composed of β" and β phases.

In order to investigate the effect of laser power on the organization and properties of iron-based alloys, iron-based alloy coatings were prepared on the surface of 45 steel using laser cladding technology, and the specimens were analytically characterized through microstructure observation, hardness experiments, and electrochemical tests to study the effect of different laser powers (1 100, 1 400, 1 700, and 2 000 W) on the organization and properties of iron-based alloy coatings. The results show that the coatings prepared with different laser powers have no defects such as porosity and cracks, and are well combined with the substrate. The phase composition of the coating mainly consists of α-Fe, γ-(Fe,Ni), α-(Fe-Cr), and γ-(Ni-Cr-Fe) phases. With the increase of laser power, the dilution rate of the coating increases, the equiaxed grains also increase gradually, and the hardness tends to increase first and then decrease. When the laser power is 1 400 W, the coating hardness is 565.4 HV0.2 at maximum, E_corr is -0.339 V at maximum, i_corr is 3.19×10^-6 A·cm^-2 at minimum, and R_ct is 71.8 kΩ at maximum, with the best corrosion resistance.

The high-temperature alloy GH3536, celebrated for its exceptional thermal stability and oxidation resistance, is of paramount importance in sectors such as aeronautics and astronautics. However, conventional manufacturing techniques are limited to produce complex structural components. Thus, laser powder bed fushion (LPBF), an advanced near-net-shape manufacturing process, is increasingly recognized as a vital technology for the rapid fabrication of high-temperature alloy parts with intricate geometries. In this study, LPBF was employed to fabricate GH3536 high-temperature alloy components, and the effects of process parameters on microstructural characteristics and mechanical performance were systematically analyzed. The main phase structure of GH3536 high-temperature alloy formed by LPBF is FCC structure, accompanied by a small amount of M₂₃C₆ phase and martensitic (α) phase, with a multi-level structure of molten pool-large columnar crystals-super cellular crystals. It is also observed that upon increasing energy density, the density initially increased but subsequently decreases. The optimal processing window for GH3536 high-temperature alloy formation is identified as between 104.00 and 120.00 J/mm³, achieving a density in excess of 99.5%. Notably, at an energy density of 104.17 J/mm³, the alloy exhibited fine cellular crystal structures and high density. Under these optimal conditions, the GH3536 high-temperature alloy exhibits an exceptional combination of strength and ductility, achieving a yield strength of 649.45 MPa, a tensile strength of 854.74 MPa, and an elongation of 32.30%.

The energy density of traction Li-ion battery is its most important performance index. The metal lithium anode possesses ultra-high theoretical capacity (3 860 mAh/g) and ultra-low reduction potential (-3.04 V H⁺/H), and the energy density of the battery can be greatly improved by replacing the graphite anode. However, the biggest problem metal lithium anode suffer from is the electrochemical instability with the electrolyte, which result in intensified side reactions, the consumption electrolyte and the increasing the capacity decay. In addition, the growth of lithium dendrites caused by side reactions at the interface also increases the safety hazard and restricts the development of lithium metal batteries. To solve the as mentioned problems, in this study, magnetron sputtering method is used to deposit lithium phosphate (Li₃PO₄) as an artificial solid electrolyte interphase on the surface of lithium metal anode, so as to obtain high electrochemical stability of the lithium metal/electrolyte interface, and effectively inhibits the polarization of the battery. At the same time, the growth of lithium dendrites is also inhibited due to the increased lithium plating and stripping uniformity. With the modification of Li₃PO₄, which is ionic conductive and electron blocking, the time-constant mode critical circuit density increases from 1.6 mA/cm² to 3.6 mA/cm², and the capacity-constant mode critical circuit density increases from 4.0 mA/cm² to 8.6 mA/cm². The assembled pouch battery achieves an energy density of 355 Wh/kg and a capacity retention rate of 90.8% after 150 cycles at 0.2 C.

The combustible metal aluminum powder which is generated at the production and processing process in the industrial and trade industry has a greater risk of explosion. Building a combustion and explosion characteristics system of aluminum powder will help provide the key data support for the prevention and control of aluminum dust explosions. This review systematically discussed the experimental methods and results of aluminum powder flame speed, flame temperature, ignition sensitivity, and maximum explosion pressure, and then provided the commonalities and differences in the conclusions of aluminum powder combustion and explosion research and explored different experiments factors affecting the results. Finally, the evolution rules of the combustion and explosion characteristics of aluminum powder under different influencing factors were discussed.

With the rapid development of new energy vehicles, communications, and other technologies, there is an increasing demand for high-performance pure copper radiators with complex structures. Traditional forging, casting, powder metallurgy pressing and other processes are difficult to manufacture complex structure products, while machining, 3D printing and other processes are more costly, not easy to promote on a large scale, the metal powder injection molding process has the advantage of low-cost, batch manufacturing of complex shaped products, and is expected to realize the complex structure of the scale manufacturing of pure copper radiator. At present, the pure copper powder injection molding process faces technical challenges such as high cost of spherical powder and low sintered density. Therefore, this paper systematically summarized the research progress of pure copper powder injection molding process, focused on the research status of key processes such as feedstock preparation, injection molding, debinding and sintering, and put forward suggestions for future development, in order to provide references for advancing the engineering application of pure copper injection molding process.

The powder of GH4698 superalloy was prepared by supreme speed plasma rotating electrode processing (SS-PREP), and a test billet was sintered by hot isostatic pressing (HIP). After the standard heat treatment, the microstructure and tensile properties of the powder metallurgy GH4698 was investigation. In this work, the mechanical properties of GH4698 superalloy prepared by SS-PREP+HIP+heat treatment route can meet the requirements of forgings. The average tensile strength at room temperature and 750 °C is 1 325 MPa and 873 MPa, respectively, which is better than cast wrought+heat treatment process. The average elongation at room temperature and 750 ℃ are 26.7% and 6.6%, respectively, which is slightly lower than that of cast wrought + heat treatment process. The average impact energy and toughness at room temperature are 60.1 J and 75.3 J/cm², respectively.

This paper systematically reviews the research progress and applications of light-curing 3D printing technology in various fields. Firstly, the principles and main methods of light-curing technology are introduced, including stereolithography (SLA), mask projection stereolithography (MPSL), two-photon polymerization (TPP), and digital light processing (DLP), with analysis of their technical characteristics. Secondly, the composition, modification methods, and research status of photosensitive resins for performance enhancement are discussed in detail. The focus is on the applications of light-curing technology in medical fields (such as dental restoration, tissue engineering scaffolds, tumor models, and flexible monitoring sensors), as well as in electronic information and mechanical manufacturing. Finally, the future development directions of light-curing technology are prospected, emphasizing the key role of material innovation and process optimization in promoting the integration of medicine and engineering and intelligent manufacturing.

The stress and deformation of overhanging structures in laser powder bed fusion (LPBF) are critical issues for achieving high-quality and high-precision manufacturing of complex metal components. Real-time strain data measurement during the LPBF process of overhanging structures was achieved by embedding strain gauges in the substrate. Based on the in-situ strain measurement system, the strain behavior of T-shaped overhanging structures and low-angle overhangs (5° and 10°) during the LPBF process was investigated. The effects of different cantilever lengths and various process parameters on the in-situ strain behavior of T-shaped overhangs were analyzed in detail. Furthermore, the influence of different overhang angles and support types on the in-situ strain behavior of low-angle overhanging structures was analyzed. The results indicate that the longer the overhanging length of the T-shaped structure, the greater the deformation. The use of a laser energy gradient and island scanning strategy effectively reduces the deformation of T-shaped overhanging structures. Additionally, the design of the support structure significantly affects the strain behavior and forming quality of low-angle overhanging structures. The optimal forming quality is achieved using the H1 support design strategy (block support spacing of 0.8 mm and conical support spacing of 0.6 mm). These findings provide valuable insights for understanding and controlling the deformation behavior of overhanging structures in the LPBF process.

To address the challenge of low-pressure powder laying while ensuring high packing density, the influence of the two-stage powder spreading spreader on the quality of the powder bed of binder jetting additive manufacturing (BJAM) is investigated. The effects of roller, scraper, and two-stage powder spreaders on the quality of the powder bed and substrate pressure were compared. Additionally, the impact of the pre-spread layer thickness of the two-stage powder spreader on powder spreading was analyzed. The powder dynamics during the spreading process were examined using the discrete element method to validate the experimental results.The findings indicate that, under the same layer thickness and spreading speed, the quality of the powder bed achieved with the two-stage powder spreading is comparable to that of roller powder spreading and superior to scraper powder spreading. However, the average pressure on the bed with two-stage powder spreading is significantly lower, at 427 Pa, compared to 2178 Pa with roller powder spreading. The pre-spreading layer thickness significantly affects the compaction effect of the powder bed. When the pre-spreading layer thickness increases from 150 μm to 250 μm, the packing density of the powder bed shows a notable improvement. However, beyond 250 μm, the density growth tends to saturate, while the substrate pressure continues to rise steadily with further increases in the pre-spreading layer thickness. These findings provide theoretical insights for optimizing powder spreading mechanisms and process parameters in BJAM, offering a viable strategy to enhance manufacturing efficiency and part reliability.

The diamond/Ni-Cu composite specimens which can be used in the carcass of polycrystalline diamond compact (PDC) drills were successfully prepared by using electron beam selective melting (EBSM) technology, and the effects of diamond volume fraction on the density, flexural strength, wear resistance and erosion resistance of diamond/Ni-Cu composites were systematically investigated. The results indicate that with the increase of diamond volume fraction, the density and flexural strength of diamond/Ni-Cu composite samples generally show a trend of first decreasing, then entering a relatively stable stage, and then rapidly decreasing. However, the wear ratio of diamond/Ni-Cu composites specimens shows a trend of increasing first and then rapidly decreasing when the volume fraction of diamond increases from 10% to 35%, and the wear ratio reaches the maximum value of 1.08 when the volume fraction of diamond is 25%. However, the erosion mass loss of the diamond/Ni-Cu composite specimens shows a trend of first decreasing and then increasing as the volume fraction of diamond gradually increases from 10% to 35%. When the weight loss reaches the minimum value of 7.50 mg, the volume fraction of diamond is 25%. Therefore, when the diamond volume fraction is 25%, the wear resistance and erosion resistance of the diamond/Ni-Cu composites prepared by EBSM are optimized simultaneously.

To investigate the influencing factors of crack formation and the wear mechanism of Fe₃Al/Cr₃C₂ composites, orthogonal experiments were conducted by laser cladding Fe₃Al/Cr₃C₂ composite coatings on carbon structural steel substrates. The coatings were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and wear tests. The results show that among the factors affecting crack formation in the cladding layer, the Cr₃C₂ content is the most critical. Coatings with 15% and 25% Cr₃C₂ exhibit the fewest cracks. In terms of wear resistance, these same coatings also display the lowest wear rates, which can be attributed to their reduced tendency for adhesive wear and the refined microstructure of the reinforcing phases that facilitate surface separation during abrasion. The morphology and distribution of the reinforcing phases in the cladding layer play a crucial role in wear resistance. During friction, the softer Fe₃Al matrix wears away first, while the harder carbides support the worn surface and reduce friction. As wear progresses, the carbides gradually disappear from the surface and transform into hard phase particles.

This article provides a brief overview of the overall development and the breakdown of PM (powder metallurgy) products usage of China's powder metallurgy products industry. It covers the growth and market structure of the traditional powder metallurgy parts sector in China, as well as recent developments in automotive components, home appliance parts, and oil-impregnated bearings. The main technological advancements in China's powder metallurgy parts are briefly outlined. It also touches upon the impacts of the rapid development of new energy vehicles in China on the traditional ICE vehicle market and its subsequent effects on the traditional powder metallurgy parts industry. Additionally, it offers a brief analysis of the opportunities and challenges that the China's powder metallurgy products industry is likely to encounter in the future amid the rapid growth of emerging industries.

Additive manufacturing enables the fabrication of metallic porous materials that combine the inherent advantages of metals, such as exceptional heat resistance and corrosion resistance, with multifunctional characteristics including high specific surface area and controllable permeability. This study employed laser powder bed fusion (LPBF) to achieve controllable preparation of porous CM247LC nickel-based superalloy through precise modulation of laser power and scanning velocity. The results demonstrate that the LPBF-processed CM247LC alloy primarily consists of γ/γ′ phases, exhibiting an average grain size of 20 μm. Mechanical properties show significant degradation with decreasing relative density. The relative density of 98% superalloy manifests a tensile yield strength of 989.1 MPa and ultimate tensile strength of 1 395.4 MPa, whereas the porous specimen with 60% relative density displays drastically reduced strengths of 132.8 MPa and 223.2 MPa, respectively. Deformation analysis reveals that the dense material undergoes plastic deformation via dislocation slip, evidenced by characteristic river patterns on fracture surfaces. In contrast, the porous structure fails through brittle fracture at sintering necks, highlighting the critical role of porosity in governing failure mechanisms.

WE43 magnesium alloys exhibit significant potential for applications in aerospace, biomedical, and transportation fields. Laser powder bed fusion (LPBF) technology offers a novel approach to optimize their properties. However, the mechanical performance of magnesium alloys produced via this method is often limited by the anisotropy of their microstructure.In this study, the effects of different deposition orientations on the microstructural evolution and mechanical properties of LPBF-fabricated WE43 magnesium alloys were systematically investigated. The results indicate that the anisotropy in mechanical behavior is closely related to the deposition direction. Specifically, the vertically deposited specimens exhibit an average grain size of 1.86 μm, contributing to a fine-grain strengthening effect. In addition, the high density of low-angle grain boundaries hinders dislocation motion, further enhancing mechanical strength. Moreover, under tensile loading along the build direction, the orientation of existing cracks becomes parallel to the applied stress, thereby reducing crack propagation and improving tensile performance.As a result, vertically deposited specimens demonstrate superior tensile properties compared to the horizontally deposited counterparts, with a yield strength of 282 MPa, an ultimate tensile strength of 325 MPa, and an elongation of 12%. This study provides a theoretical basis for optimizing LPBF deposition strategies and lays a technical foundation for the directional design of microstructure and properties in WE43 magnesium alloys.

Laser powder bed fusion (LPBF) processes exhibit highly dynamic, transient, and spatially small-scale characteristics such as keyholes, melt pools, and particle spattering. Conducting in-situ high-speed imaging of powder melting processes aids in deepening our understanding of melt pool dynamics and defect formation mechanisms. This study developed an in-situ imaging system for LPBF using a high-resolution open micro-focus X-ray tube. Observational research focused on phenomena including keyholes, bubble, spattering, and balling during the melting of 316L powder. The results demonstrate the system's capability to detect dynamic changes at the gas/melt pool interface and capture morphological changes of keyholes under certain laser process parameters, including the formation process of keyhole-induced large-scale porosity (~100 μm). Furthermore, it is found that higher X-ray tube voltages (e.g., 220 kV) enhance the system's ability to discern melt pools, although excessive X-ray penetration at this level prevents imaging of small-sized spatters. Conversely, lower X-ray tube voltages (e.g., 90 kV) effectively capture spattering behavior (~30 μm and above), preliminarily revealing mechanisms such as spatter-induced surface protrusions, significant dimensional deviations, and surface rippling defects in melt tracks. Additionally, dynamic processes of balling are replicated. The development of this technology holds significant implications for advancing in-situ studies of materials and processes in additive manufacturing.

Laser powder bed fusion (LPBF) offers a novel pathway for enhancing the performance of lightweight steels through its superior forming capability and microstructure refinement potential. However, current research lacks systematic investigation on LPBF processing of Fe-Mn-Al-Ni-C lightweight steels with high Ni content, while the evolution mechanism of B2 phase and its influence on mechanical properties remain unclear. This study investigates Fe-30Mn-11Al-12Ni-1C lightweight steel through comparative analysis of as-built and heat-treated specimens, focusing on matrix microstructure evolution, B2 phase morphology, dimensional characteristics, and spatial distribution. A defect-free sample with 99.2% relative density was successfully fabricated under optimized parameters (laser power at 95 W, scanning speed at 800 mm/s), followed by microstructure regulation through 1 100 ℃ and 1 200 ℃ heat treatments. The results reveal that the as-printed steel predominantly consists of FCC-γ austenite phase, with angular polygonal B2 particles (average size at 68 nm) discontinuously distributed along grain boundaries, occupying 12.43% area fraction. After 1 100 °C treatment, B2 phase transforms into short rod-like morphology (average length at 0.93 μm) with homogeneous intra- and intergranular distribution, significantly increasing its area fraction to 52.14%. The 1 200 °C treatment induces banded B2 phase formation (average length at 1.89 μm), reducing area fraction to 41.03%. Mechanical characterization demonstrates that 1 100 °C-treated specimens exhibit enhanced microhardness (468.5HV0.2), yield strength (930.2 MPa), and ultimate tensile strength (1 012.6 MPa), but suffer from severe ductility reduction (elongation at 0.88%). The study elucidates that increased B2 phase content and coarsening strengthen materials via secondary phase strengthening mechanism, while their inherent brittleness critically deteriorates matrix plasticity.

A technology to modify the surface of the substrate with alumina powder particles was proposed, and the alumina particles with a diameter of tens of microns were successfully embedded into the metal surface layer of 5052 aluminum alloy at high speed and accurately by using a laser oscillator combined with a sandblasting device. The laser-induced powder jet technology uses a laser to melt the surface layer of the substrate only , and then uses high-speed jetting of alumina particles to quickly embed in the molten layer of the aluminum alloy substrate to enhance the surface properties of the material. The cross-section of the sample was observed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), and the depth of the embedded particles could reach about 100 μm, and the number and distribution range of the embedded alumina particles were detected. The effects of key process parameters such as jet pressure, laser energy flow density (the flow rate of laser energy per unit area) and particle incidence angle on the embedding depth, embedding amount and particle percentage were further discussed, which provided a theoretical basis and experimental data support for optimizing the process conditions of this technology. The successful development of this technology not only expands a new way of surface modification of materials, but also provides a new technical solution for improving the wear resistance and corrosion resistance of metal materials.

Cu-12.5Ni-5Sn alloy was prepared using spark plasma sintering (SPS). The effects of sintering temperature, sintering pressure and holding time on the densification and mechanical properties of the alloy were investigated. The optimal SPS conditions as well as the relationship between microstructure and mechanical properties of the alloy were explored. The results show that the densification, hardness and yield strength of alloy all show a trend of first increasing and then decreasing with the increase of sintering temperature, sintering pressure and holding time. When the sintering temperature is about at 870 ℃, the sintering pressure is about 25 MPa, and the holding time is about 30 min, the densification of the alloy is above 98%, and the hardness and yield strength of the alloy after aging treatment reach the maximum values of 252HB and 468 MPa, respectively. Aging treatment can promote further refinement and formation of the lamellar structures in alloy. The γ-CuNi₂Sn phases enriched with Ni and Sn with different shapes are formed at grain boundaries and within grains after aging treatment. In addition, the lamellar γ-CuNi₂Sn phases are identified as discontinuous precipitated γ-DO₃ phases, which are alternately arranged with the spinodal structures to form sandwich structures. The spinodal decomposition strengthening and precipitation strengthening are the main reasons for the good mechanical properties of the alloy.

Laser powder bed fusion (LPBF) additive manufacturing has made significant progress in fabricating multi-material metallic structures, where the quality of the heterogeneous powder bed is a critical factor affecting the final part quality. Among these factors, interparticle cohesion plays a pivotal role in the powder spreading process. Taking 316L stainless steel and CuSn10 alloy as examples, the discrete element method is used to numerically simulate the spreading process of multi-material powder beds, so as to evaluate the influence of interparticle cohesion on the quality of powder layers. Additionally, the impact of cohesion on the formation of sharp interfacial boundaries along the powder spreading direction was examined. Key findings include: (1) Increased interparticle cohesion worsens powder spreadability and exacerbates particle size segregation. (2) Cohesion induces powder agglomeration, leading to cross-contamination. (3) Higher cohesion reduces powder flowability, increases the angle of repose, and results in poor boundary quality with steep gradients.

The TiAl alloys were prepared by laser coaxial powder feeding additive manufacturing technology, and the evolution of metallurgical defects in the alloy under different laser powers was thoroughly investigated, and the phase composition, microstructure, and mechanical properties of the alloy were analyzed. The results indicate that as the laser power increases, the melt width and depth of the single melt track in the TiAl alloy gradually grow, and the spheroidization phenomenon diminishes. The alloys demonstrate a high density, with porosity below 0.05%, and the porosity slightly decreases as the laser power increases. When the laser power is 1 200 W, cracks appear near the interface between the formed part and the base material. When the laser power is increased to 1 400 W and 1 600 W, the cracks disappear. The TiAl alloys are mainly composed of the γ phase and a small amount of the α₂ phase. Their microscopic structure feature is that a small number of blocky γ grains are distributed at the boundaries of the γ/α₂ lamellar colonies. With the increase of the laser power, the size of the lamellar colonies of the TiAl alloys shows a gradually increasing trend. When the laser power is 1 400 W, the tensile strength of the TiAl alloy is 476 MPa, and the tensile fracture morphology exhibits the characteristics of brittle fracture.

To study on the influence of powder preparation processe on NiCrAlY powders and coatings.Atmospheric Plasma Spraying (APS) were prepared using Ni-Cr-Al-Y alloy powders fabricated by the close-coupled gas atomization and the ultrasonic gas atomization. The physical properties,morphology, elemental distribution,internal microstructure and phase composition of the NiCrAlY alloy powders and coatings were compared. The results show that the two powders have the similar chemical composition and physical properties,with both exhibiting a near-spherical particles shape,but differing in particle size composition.Their microstructures are both composed of dendrites and cell-like structure. The yield and the solidification cooling rate of close-coupled atomization powder with the particle size of 45-90 μm are 30.69% and 1.25-2.49×10⁴ k/s. In contrast, the yields and the solidification cooling rate of ultrasonic gas atomization powder with the particle size of 45-90 μm are exceed 60% and 1.18-2.08×10⁴ k/s, and the distribution of the dendrities and cellar crystals is more regular.Two APS coating have a typical layered structure. The coating fabricated by the close-coupled gas atomization powder has a porosity rate of 12.81% and a bonding strength of 36.8 MPa. In comparison, the coating fabricated by the ultrasonic gas atomization powder has a porosity rate of 11.35% and a bonding strength of 34.8 MPa. Close-coupled gas atomized and ultrasonic gas atomized powders differ in particle size distribution and phase structure. The coatings prepared from the two atomized powders have similar cross-sectional morphology, element distribution, and coating properties. For the close-coupled gas atomized powder contains more fine particles and has a complex phase structure, which leads to significant changes in the element content of the coating, along with poor crystallinity, high porosity, and high microhardness.

The relationship between process parameters and microstructure evolution during the deposition process of typical Ni₃Al-based alloy IC-221M prepared by laser directed energy deposition was analyzed, and the mechanical properties at room temperature were obtained. The results of scanning electron microscopy show that the microstructure of the alloy is mainly composed of γ-Ni₅Zr eutectic and γ + γ ' low melting point eutectic phase, as well as the spherical γ ' phase at the dendrite. As the scanning speed increases, the (200) diffraction peak shifts to a low angle, the interplanar spacing and lattice constant gradually increase, and the grain size in the solidified structure gradually decreases. In terms of mechanical properties at room temperature, when the laser scanning speed is 700 mm/min and 800 mm/min, the mechanical properties of IC-221M alloy samples are higher than those of as-cast alloys, the yield strength is higher than 550 MPa, the tensile strength is higher than 750 MPa, and the fracture elongation is more than 13%.

Based on the reduction reaction and thermodynamic model, a systematic analysis was conducted on the thermal energy consumption and structural composition of the two-stage reduction process of molybdenum powder using a horizontal four-tube furnace as the reduction equipment. The results show that the heat consumed in the reaction process accounts for 17.87%, while the heat carried away by the excess reaction gas accounts for 68.54%. From the perspective of energy consumption management, energy consumption management strategies for the two-stage reduction process of molybdenum powder were proposed from three aspects: thermal efficiency improvement, heat loss control, and thermal effect assurance. Firstly, the thermal efficiency is improved through precise regulation of the hydrogen atmosphere in the reduction furnace; secondly, heat loss is reduced by combining equipment inspection with waste heat recovery and utilization; thirdly, the thermal effect is ensured by optimizing the equipment temperature control and data monitoring system. These multiple measures provide directions for equipment transformation and process optimization.

The microstructure difference of GH4099 alloy formed by laser powder bed fusion and conventional casting was studied. The microstructure evolution of GH4099 alloy formed by the two processes after heat treatment was further analyzed and its effect on mechanical properties was discussed. The results show that the microstructure of GH4099 alloy formed by laser powder bed fusion (LPBF) and cast is epitaxial growth near columnar crystal structure and bimodal equiaxed crystal structure, respectively. The dendritic structure in the grains of the alloys formed by the two processes disappeares, and the carbides and γ' phase precipitate in the subsequent heat treatment, resulting in an increment in ultimate tensile strength and a decrement in plasticity. Compared with cast GH4099 alloy, LPBF GH4099 alloy has static recrystallization and grain refinement after heat treatment, which increases the utimate tensile strength, yield strength and elongation of GH4099 alloy by 66MPa, 187MPa and 14.5% respectively.

In order to provide systematic theoretical support for the optimisation of the preparation process of metal-bonded diamond tools, the effects of different metals on the properties of diamond under hot pressing conditions were experimentally investigated. The metal bond prepared in the hot pressing and sintering process was corroded by the acid corrosion method, and the diamond obtained after corrosion was compared and analysed with the original diamond in terms of surface morphology, surface corrosion rate, corrosion depth, etc., and the diamond was tested for compressive strength. The results show that with the increase of temperature, the surface corrosion rate of diamond rises and the surface corrosion depth gradually increases, which leads to a significant decrease in the compressive strength of diamond. Under the same hot pressing conditions, after the hot pressing sintering of Fe, Co, Ni, Cu, Cr and Ti, the surface morphology and properties of diamond show different degrees of changes. Specifically, under the hot pressing and sintering condition at 700 ℃, Ti has the least effect on the compressive strength of diamond, and the corrosion rate and depth of diamond are 66.7% and 0.453 μm, respectively, compared with Cr and Fe, which have a significant decrease in the compressive strength of diamond, and the corrosion depth of diamond is higher than the corrosion results of the other metals. Raman analyses reveal that the surface structure and properties of diamond do not change significantly in most cases, and only a few graphite structures appear after Fe and Co corrosion.

In this work, spherical WC-Co powder and nylon powder as the binder were used as raw materials for 3D printing of complex-structured cemented carbide components via the selective laser sintering technology, where nylon was melted at a low temperature. Post-processing steps including debinding and sintering were subsequently applied to enhance the density and mechanical properties of the printed parts. The effects of sintering processes on the microstructure and mechanical performance of the printed cemented carbides were studied in detail. The results demonstrate that all samples subjected to different post-treatments exhibite pure phase compositions, highlighting a distinct technical advantage over other thermal printing methods that often lead to carbon-deficient phases. Based on the proposed post-processing process combining atmospheric-pressure pre-sintering and secondary gas-pressure sintering, the printed cemented carbides achieve a nearly fully dense microstructure and exceptional comprehensive mechanical properties. With an average grain size of 2.8 μm, the printed cemented carbide has an average Vickers hardness of 1 247HV30, fracture toughness of 20.1 MPa·m^1/2, compressive strength of 3 542 MPa, and transverse rupture strength of 1 861 MPa, respectively. Through comparative analysis of microstructures obtained under different sintering conditions, the densification mechanism of SLS-printed cemented carbides via the two-step sintering method is systematically elucidated.

The evolution mechanism of molten pools and microstructure distribution in the process of preparing 18Ni250 maraging steel by selective laser melting (SLM) technology were explored through simulations and experiments. The research focuses on the molten pools, microstructure evolution and mechanical property testing of SLM-formed parts. Simulation results show that the Marangoni effect occurs when metal powder melts under laser loading, which makes the surface relatively smooth after the molten pool solidifies. Experimental results indicate that the prepared metal bulk has a flat and dense surface. The molten pool sizes obtained from simulation and experiment are quite consistent, suggesting that the prediction of printing quality through simulation is reliable. After heat treatment, the SLM-18Ni250 parts have a tensile strength of 1 970 MPa and a yield strength of 1 900 MPa, which are comparable to those of traditionally forged 18Ni250 maraging steel, but with slightly lower toughness. Observation of the metallographic structure of SLM-18Ni250 reveals that the as-printed molten tracks are regularly distributed, and the microstructure consists of a small amount of austenite and martensite. The solution water quenching treatment transforms austenite into martensite, and after aging and air cooling treatment, the martensite increases significantly with uniform composition, thereby improving the mechanical properties of the material. However, the interlayer bonding and defect distribution of the printed parts result in slightly lower toughness. The research method and idea combining simulation and experiment can provide useful guidance for the preparation of high-strength and high-toughness maraging steel by SLM technology.

As one of the important technologies in powder metallurgy, hot-isostati-pressing near-net-shape (HIP-NNS) technology has been widely used in the aerospace field in recent years, it has ability to prepare high-performance products with complex structures. Due to their excellent mechanical properties and corrosion resistance, duplex stainless steel (DSS) products have attracted attention from marine engineering, shipbuilding, nuclear power, petrochemical and other industries. HIP-NNS technology, Shima plastic deformation model and MSC. Marc finite element software were used in the paper. The densification of DSS powder simulation and the prediction of deformation size were completed, and the changes in powder relative density and equivalent stress were analyzed .The results show that the numerical model achieves high prediction accuracy, with a maximum size error of no more than 3%. The numerical simulation method is used to accurately predict the deformation of the package and the powder densification process, greatly improving powder utilization and production efficiency, reducing processing costs, and providing a innovative approach for achieving integrated forming of complex DSS products.

High-nitrogen steel samples were prepared by adding chromium nitride into the powder and using laser selective zone melting technology at atmospheric pressure, and the effects of different laser parameters on the organization, physical phase and mechanical properties of high-nitrogen steel were systematically investigated. The experimental results show that when the laser energy density increases, the defects of the samples show a trend of increasing and then decreasing. When the laser energy density is too high, it will aggravate the overflow of nitrogen in the powder to form more defects. The physical phase of the sample is dominated by austenite and ferrite, martensite and the austenite phase content of the sample decreases with the increase of laser energy density. The samples with chromium nitride added have a yield strength of 822-1 057 MPa at 1 134-1 254 MPa and an elongation of 9.6%-16.64%. The fracture behavior of the samples is mainly dominated by ductile fracture, and some regions are brittle fracture. The fracture behavior of the samples was mainly characterized by ductile fracture when the energy density was 130.21 J/mm³ (laser power 250W, scanning speed 800 mm/s, scanning spacing 0.08 mm, powder thickness 0.03mm), the overmatching powder laser selective zone melting and forming specimens showed the best mechanical properties.

The nine-claw synchronizer cone ring is a critical component used in the lock-pin synchronizers of heavy-duty truck transmissions with high torque requirements. This study investigates the manufacturing process of the nine-claw synchronizer cone ring using powder metallurgy (PM) technology as an alternative to traditional casting and forged steel methods. The selected material is a diffusion-alloyed powder blend of Fe-0.5Mo-4.0Ni-1.5Cu-0.8C, and the manufacturing process includes powder compaction, sintering with copper infiltration, precision machining, and heat treatment. The resulting PM nine-claw cone ring achieves a density of 7.49 g/cm³, a surface hardness of HRC 31, and a tensile strength of 623 MPa, meeting all performance requirements for transmission assembly and service life in heavy-duty trucks. The powder metallurgy process overcomes the drawbacks of the original 40Cr cast steel cone ring, including excessive weight, high machining demands, complex procedures, low production efficiency, and high costs. This method offers advantages such as reduced machining, energy and material savings, high efficiency, and low cost, making it suitable for mass production.

In this study, selective laser melting (SLM) forming process was successfully employed to fabricate a CuCrZr/316L bimetallic structure, and heat treatment strengthening was also carried out. By means of optical microscope, X-ray diffractometer, scanning electron microscope etc., the interface phase composition and microstructure of the prepared CuCrZr/316L bimetallic structure were characterized and analyzed. Its mechanical properties and the main factors influencing the interfacial bonding performance were further investigated. The results show that the interface of the CuCrZr/316L bimetallic structure can be divided into three parts: the copper-rich layer, the mixed layer, and the iron-rich layer. In the as-formed state, fine grain strengthening and second phase strengthening at the interface make the interface bonding strength higher than that of the CuCrZr matrix. However, the Cu element in the iron-rich layer will cause the embrittlement of the iron matrix, and cracks will be generated during SLM process because of thermal stress. After heat treatment, the hardness of the CuCrZr matrix increases, which leads to a change in the fracture position of the heat-treated CuCrZr/316L bimetallic structure from the CuCrZr matrix to the iron-rich layer in the tensile test, and the fracture mode is transformed from ductile fracture to brittle fracture. The tensile strength increases from 216.7 MPa to 443.9 MPa, while the elongation decreases from 37.5% to 3.0%.

In laser powder bed fusion (LPBF), the quality of powder spreading directly affects the performance and forming quality of the components. Current research primarily focuses on blade-based powder spreading, while the exploration of roller-based spreading and its microscopic mechanisms remains relatively limited. Moreover, most studies are based on mono-sized powders, which differs significantly from the continuous size distribution in practical processes. To address this, this study employs the discrete element method (DEM) to simulate the roller-based spreading process of 316L stainless steel powder and combines it with computational fluid dynamics (CFD) to analyze the laser melting behavior under different gap heights. The influence of process parameters on the macroscopic and microscopic properties of the powder bed is systematically investigated, and the results are compared with those of blade-based spreading. The results show that when the roller velocity is 0.04 m/s and the rotational velocity is -15 rad/s, the powder bed exhibits high packing density and excellent uniformity. The quality of the powder bed achieved by roller-based spreading is superior to that of blade-based spreading. Kinetic analysis indicates that as V increases, the motion velocity of powder particles accelerates, and the force chains between the powder and the substrate strengthen, leading to reduced flowability, clogging phenomena, and a subsequent decline in powder bed quality.

in this paper, ultrafine silver powder was prepared by liquid-phase chemical method. The effects of feeding rate, reaction temperature, concentration of silver nitrate, refining dose and alkali temperature on the properties of ultrafine silver powder were studied, the morphology was observed by scanning electron microscopy (SEM). The results show that when the AgNO₃ concentration, AgNO₃ feeding rate, reaction temperature, refining dose and alkali temperature are 0.15 mol/L、200 L/S、55 ℃、35 g、30 ℃, the agglomerations of ultrafine silver powder are less, the particle sizes are uniform and the distribution is concentrated, show excellent performance.

The characteristics of single-pass and single-layer cold-sprayed pure Cu coatings have not been extensively studied. In this research, cold spray technology was employed to deposit single-pass and single-layer pure Cu coatings onto 6061 T6 Al alloy plates under varying gas temperatures and pressures. The surface roughness of the coatings was measured using a three-dimensional profilometer, while the thickness, microstructure, and phase composition were analyzed using OM, SEM, and XRD techniques, respectively. SEM images, in conjunction with Image Pro software, were used to calculate the porosity of the coatings. Additionally, the microhardness and shear strength of the coatings were evaluated using a micro Vickers hardness tester and a universal mechanical testing machine, respectively. The shear fracture morphology of the coatings was observed using SEM. The results indicate that an increase in gas temperature results in higher coating thickness and shear strength, accompanied by a gradual decrease in surface roughness, porosity, and microhardness. Conversely, increasing gas pressure lead to corresponding increases in surface roughness, microhardness, and shear strength, while reducing porosity. Ultimately, the study elucidates the relationship between the microstructure and mechanical properties of single-pass and single-layer pure Cu coatings and spraying parameters, laying a foundation for further research on high-performance pure Cu coatings.

A composite gradient porous membrane material was successfully prepared using a combination of cold isostatic pressing, centrifugal deposition molding technology, and vacuum sintering, with 316L porous stainless steel as the matrix and ZrO₂ as the membrane layer. The phase composition, microporous structure morphology, and pore properties of porous materials were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and a porous material integrity tester. The influence of sintering temperature on the pore structure morphology, air permeability coefficient, and pore size distribution of 316L-ZrO₂ composite gradient porous membrane material was studied, and finally its filtration application in the treatment of oily and saline wastewater was studied using dead-end filtration technique. The results show that by introducing a correction factor K into the formula for calculating the thickness of the gradient membrane layer, accurate control of the membrane thickness can be achieved. In this experiment the K value ranged from 0.21 to 0.25. The permeability of the membrane material decreases gradually as the sintering temperature rises, and the reduction in the permeability coefficient is more pronounced at 700-800°C. Meanwhile, the average pore size of the membrane layer becomes smaller, decreasing from 0.28 µm to 0.18 µm. The 316L-ZrO₂ composite gradient porous membrane can effectively remove suspended solids from oily and saline wastewater, but has poor removal effects on COD, ammonia nitrogen, and soluble salts.