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20 June 2025, Volume 32 Issue 3
    

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    EXPERT FORUM
  • Research progress of high entropy superalloys
    YANG Suyuan, ZHOU Lang, MA Zhaolong, CHENG Xingwang
    Metallic Functional Materials. 2025, 32(3): 1-7. https://doi.org/10.13228/j.boyuan.issn1005-8192.20250065
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    High entropy superalloy (HESA), as a research hotspot in the field of metal structural materials, has attracted wide attention due to its potential application value in extreme environments. The composition characteristics and microstructure design of high entropy superalloy are systematically described. In terms of element composition, the high entropy system is constructed by using the ratio of multiple components with equal or near equal atomic ratio. In terms of structure, the performance of face-centered cubic solid solution is optimized through the synergistic interaction between the matrix and the ordered precipitated phase. Studies have shown that HESA can maintain excellent strong plastic matching over a wide temperature range (room temperature -1 200 ℃), and its mechanical stability is due to the synergistic effect of multi-scale strengthening mechanisms, including lattice distortion strengthening caused by solid solution atoms, second phase strengthening caused by nanoscale ordered precipitates, and grain boundary strengthening achieved by grain boundary engineering. Finally, the research and application prospects of high entropy superalloys are prospected.
    • RESEARCH AND TECHNOLOGY
  • Properties and microstructure of Nd-Cu grain boundary diffusion (PrNd)-(FeCoGa)-B hot-deformed magnets with additional pressure
    LIU Ruijin, WANG Junming, CHEN Futao, GUO Zhaohui
    Metallic Functional Materials. 2025, 32(3): 8-13. https://doi.org/10.13228/j.boyuan.issn1005-8192.20240105
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    The grain boundary diffusion process of hot-deformed magnet with additional pressure was studied. The properties and microstructure of the magnet after diffusion were analyzed. The coercivity of the magnet increases from 14.19 to 24.36 kOe when diffusion with no pressure. But the height of the c-axis of the magnet increases significantly. A large number of non-magnetic phases enter the interior of the magnet and the orientation decreases significantly, which resulting in a drastic deterioration of the remanence. The remanence decreased from 14.71 to 10.00 kGs. The volume expansion in the c-axis direction of the magnet was control-led when the pressure was applied to the diffusion process. The area fraction of the rare-earth rich phase was reduced and the orientation was increased. The drastic deterioration of remanence is inhibited. After grain boundary diffusion, the coercivity mechanism of the magnet was changed and the pinning effect of the diffusion magnet was significantly enhanced, which may be the main reason for the increase of coercivity. Finally, the properties of the magnet obtained by grain boundary diffusion with additional pressure were Br=13.71 kGs, Hcj=18.63 kOe, (BH)max=46.44 MGOe.
  • Manipulation of the thermal expansion performance of Ho2Fe17 alloy
    LI Junpei, ZHOU Jingwen, CAI Yinying, LIN Zhiwei, WANG Xin, PIAO Xianzheng, MIAO Xuefei, XU Feng
    Metallic Functional Materials. 2025, 32(3): 14-20. https://doi.org/10.13228/j.boyuan.issn1005-8192.20240201
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    Zero thermal expansion materials are widely applicable in precise instruments such as optical devices, electronic equipment, and aerospace components due to their minimal volume expansion within a fixed temperature range. The strong magneto-volume effect associated with a magnetic phase transition compensates the positive thermal expansion caused by the inharmonic lattice thermal vibration, which leads to a negative thermal expansion effect. A small amount of boron was introduced into the Ho2Fe17 alloy, which leads to zero thermal expansion in a wide temperature range. The Ho2Fe17B0.2alloy exhibited a thermal expansion coefficient of only -0.74×10-6 K-1 within the temperature range of 120-350 K. Comprehensive characterizations, including scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometer, were conducted to analyze the microstructure, crystal structure, and magnetic phase transition behavior of the samples. The underlying mechanism for the regulation of thermal expansion behavior has also been discussed, which provides new insights and approaches for the development of advanced zero thermal expansion materials.
  • Preparation and properties of high-performance M-type strontium ferrite
    WANG Qin, MA Yilong, LUO Xianfu, ZHANG Yunchuan, ZHONG Yan
    Metallic Functional Materials. 2025, 32(3): 21-30. https://doi.org/10.13228/j.boyuan.issn1005-8192.20240184
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    M-type strontium ferrite was prepared by solid-phase reaction method combined with high-energy ball milling process, and the effects of ball milling time and additive type and content on the micro-morphology, crystal structure and magnetic properties of M-type strontium ferrite were investigated. The results showed that the samples had the best magnetic properties after sintering when the secondary ball milling time was 12 h, with the maximum magnetic energy product (BH)max=32.7 kJ/m3. Effect of the addition of Co3O4, CaCO3 and SiO2 on the magnetic properties of the magnets was further investigated, and the results showed that the magnetic properties decreased with the addition of Co3O4; the increase of CaCO3 content, may result in an excessive grain growth and non-uniformity, which in turn causes a gradual decrease in its coercivity, and when the content of 0.2% CaCO3, the coercivity has a maximum value of Hcj=326.7 kA/m; with the increase in the content of SiO2, the magnetic properties of the sample show a trend of increasing and then decreasing, and when the content of 0.3% of SiO2, sintered samples have a higher densification, and at this time, the sintered samples have better overall properties: Hcj=340.5 kA/m, Br=403.0 mT, (BH)max=31.7 kJ/m3. The experimental results show that the magnetic properties of strontium ferrite can be improved by adjusting the ball milling time and the different additive type and its content.
  • Development of series certified reference materials of cerium-zirconium composite oxides and discussion on the determination method
    WANG Lijuan, ZHAO Tuo, LI Xinxin, WU Wenqi, REN Xudong
    Metallic Functional Materials. 2025, 32(3): 31-37. https://doi.org/10.13228/j.boyuan.issn1005-8192.20240113
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    Cerium-zirconium composite oxides are widely used in the market as the key co-catalytic materials of high-performance ternary automobile exhaust purification catalysts. The existing standard methods and reference materials are too few to meet the needs of actual production and use. At present, cerium-zirconium composite oxide component reference material at home and abroad cannot meet the demand for multiple elements in different content ranges. Therefore, a set of three-point cerium-zirconium composite oxide component series reference materials are prepared, named respectively LH-01, LH-02 and LH-03 in this paper. In the composition design, the current product standard of cerium-zirconium composite oxide and the content range in the market are fully considered. After extensive market research and according to the general needs of customers, the composition design of the reference materials was determined. 8 authoritative and qualified testing institutions were invited to define the values of ZrO2, CeO2, La2O3, Pr6O11 and Y2O3 in reference materials, and give the standard deviation and uncertainty. The development of reference materials carried out in strict accordance with the requirements of GB/T 15000.1—GB/T 15000.8 《Directives for the work of reference materials》 and YS/T 409—2012 《Specification for certified reference materials of non-ferrous metal products for analysis》. The accurate determination of fixed element content in cerium-zirconium composite oxide reference materials lacks the standard detection method, and the detection method of fixed element is also studied in this paper.
  • Impact of corrosive atmospheric environment on the performance and coercivity of Q235 steel
    HE Bohao, HUANG Wenfei, ZHANG Chi, ZHANG Guoqing, CHEN Youpeng
    Metallic Functional Materials. 2025, 32(3): 38-43. https://doi.org/10.13228/j.boyuan.issn1005-8192.20240196
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In view of the safety problems caused by the attenuation of mechanical metal properties caused by the long-term service of construction machinery in corrosive atmospheric environments such as acid rain, Q235 steel common in engineering was selected as the experimental object and corrosion experiments were carried out under two corrosion conditions, and the coercivity of Q235 steel samples with different corrosion times was detected by hysteresis nondestructive testing equipment while recording the changes in mechanical properties during the tensile test of Q235 steel after corrosion. The results show that with the increase of corrosion time, the mechanical properties show a decay trend, and the weakening of the elastic modulus is especially obvious. In the yield stage, the yield plateau gradually disappeared, and the coercivity changed in advance, and in the strengthening stage, the corrosion time increased to 9.2 and 8.9 A/cm in the neutral and acidic salt spray corrosive environments, respectively. With the increase of corrosion time, the coercivity of the material showed a decreasing trend, and the coercivity of the material accelerated in the necking stage. The change law of coercivity in the corrosion process can reflect the degree of performance degradation of materials to a certain extent, which can provide a reference for non-destructive testing and performance evaluation of related equipment.
  • Effect of Pt and Pd alloying on the pore structure and hydrogen evolution performance of nano porous Ni
    WANG Jing, YU Yipeng, PI Shouxi, LUO Xi, LIU Junkai, ZHANG Jianfu
    Metallic Functional Materials. 2025, 32(3): 44-49. https://doi.org/10.13228/j.boyuan.issn1005-8192.20240190
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    A novel self-supported three-dimensional electrocatalyst is proposed for the development of efficient and low-cost electrocatalysts to address the key challenges in electrolytic water hydrogen production technology. Ni40Zr40Ti20 amorphous alloy precursor was alloyed with 3% Pt and Pd, and then combined with the dealloying technique to prepare flexible self-supported nanoporous/amorphous alloy composite catalysts with a honeycomb nanoporous structure. The alloyed Pt material required only 32 mV overpotential at 10 mA/cm2 current density, and the alloyed Pd porous material required 52 mV overpotential at a current density of 10 mA/cm2, Pt alloying was superior to Pd, and the porous PtNi/amorphous composite HER (hydrogen evolution reaction) performance was better than that of commercial Pt/C catalysts. The excellent electrolytic water performance of the porous PtNi/amorphous composites was attributed to their submicron honeycomb porous structure and sponge-like nanoporous structure, which exposed more catalytically active sites while ensuring the structural stability of the catalyst. Moreover, the compressive lattice strain effect was introduced due to the replacement of noble metal lattice sites by smaller nickel atoms, thus optimising the hydrogen adsorption energy. This not only opens up new avenues for developing hydrogen evolution reaction (HER) catalysts with self-supporting structures, high flexibility, and low platinum content, but also holds significant scientific importance for gaining deeper insights into alloy effects in catalytic processes.
  • Dynamic impact performance of Fe-11Mn-2Al-2Si medium manganese steel
    BAO Jianing, ZHU Shuaikang, ZHAO Xin, CAI Zhihui
    Metallic Functional Materials. 2025, 32(3): 50-57. https://doi.org/10.13228/j.boyuan.issn1005-8192.20240169
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    The Hopkinson pressure bar device was used to conduct the dynamic impact tests on manganese steel under different impact pressures in experiments after different heat treatments. To study the dynamic mechanical properties of Fe-11Mn-2Al-2Si medium manganese steel under different heat treatment conditions and strain rates, the microstructure changes before and after impact were analyzed by optical microscopy (OM), scanning electron microscopy (SEM) with energy spectrum analysis (EDS), and polycrystalline X-ray diffraction (XRD). The results show that when the quenching process remains unchanged, the TRIP effect is enhanced and the dislocation density increases due to the increase in strain rate. The yield strength and ultimate strength of the experimental steel are positively correlated with the strain rate. The austenite transformation reaches a peak value (41%) when the quenching temperature is 750 ℃. When the impact pressure is 0.7 MPa, the strain rate of the samples is large when quenched at 650 and 750 ℃, and adiabatic shear bands are generated. AlN precipitates exist in the adiabatic shear band, which improves the strength and hardness of the material, but reduces the toughness of the material.
  • Simulation of bending quality of low carbon steel rectangular tube
    WANG Cuizhu
    Metallic Functional Materials. 2025, 32(3): 58-64. https://doi.org/10.13228/j.boyuan.issn1005-8192.20240181
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In order to optimize the bending process of low carbon steel rectangular tube, the effects of core tube gap, number of cores and bending radius on the bending section quality of Q235 rectangular tube were studied. Dynaform software is used to simulate the working condition of 90° round bending of pipe blank, and the section is divided every 10° to calculate the reduction rate of mid plane height and local wall thickness reduction rate of pipe fittings on the section. The results show that the area with the most serious section distortion is close to the head of the pipe fitting, and the section angle is about 50°-70°. Increasing the number of cores can significantly reduce the section distortion of pipe fittings, but it will increase the wall thickness thinning rate of pipe fittings. When the gap of the core tube is large, the change of the bending radius has little effect on the section distortion of the tube; However, when the core tube gap is small, the reduction of the bending radius will significantly increase the section distortion of the tube. Therefore, in the actual production, the parameters such as the core tube gap, the number of cores and the bending radius can be adjusted according to the specific needs, so as to balance the cross-section distortion and wall thickness thinning rate of the pipe fittings, and improve the product quality and production efficiency.
  • Constitutive and fracture mechanics models for TC4 titanium alloy material
    LI Hongyao, LIU Fu
    Metallic Functional Materials. 2025, 32(3): 65-73. https://doi.org/10.13228/j.boyuan.issn1005-8192.20240163
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    The optimization of the constitutive model and fracture model for titanium alloy materials contributes to enhancing the accuracy of their simulations. We establishes the constitutive and fracture failure models for titanium alloy materials by conducting tensile tests on TC4 titanium alloy under various operating conditions. The constitutive model employs the Johnson-Cook constitutive equation, while the fracture model utilizes both the Johnson-Cook fracture model and the LOOKU fracture model. Simulations are conducted using Pamcrash software to compare the experimental results with the simulated load-displacement curves and the differences between the two models. By further analyzing the mechanical behavior and fracture characteristics of titanium alloy materials, a more precise and practical constitutive and fracture mechanics model is developed, and the parameters of the simulation model are calibrated.
  • Effect of stress induction on the durability of zirconia materials
    FANG Yuan, LIN Yao, XU Qiang, WANG Jingkun, QI Mengchun, DUAN Yingying, LI Chenxi
    Metallic Functional Materials. 2025, 32(3): 74-80. https://doi.org/10.13228/j.boyuan.issn1005-8192.20240191
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    In order to optimize sintering temperature and particle size of raw materials, evaluate the effect of stress induction on the toughness of materials, and study the effect of stress induction on the durability of zirconia materials. Nano-zirconia was used as the main raw material, and polyvinyl alcohol was used as the pore-making agent. After pre-treatment, such as screening and drying, zirconia raw embryo was obtained by dry pressing method combined with cold isostatic pressing method, and the raw embryo was sintered and infiltrated to obtain zirconia material. Stress induction was applied to the material, the phase transformation of the material was tested after induction, and the change of the phase transformation was tested when the sintering temperature increased, and the fracture toughness of the material was analyzed by changing the particle size of the raw material, so as to determine the change of the durability of the material. The experimental results show that cracks and phase transitions occur in zirconia materials under stress induction, and t-crystals change to m-crystals. With volume expansion, cracks are suppressed and fracture toughness is improved. With the increase of sintering temperature, the phase change content increases, the grain size increases and the toughness increases. The fracture toughness and grain size of raw materials decreased with the increase of particle size. When the particle size of 350 nm raw material, the fracture toughness of zirconia material under stress induction is better, and the durability is better.
    • APPLICATION RESEARCH
  • Flow and heat transfer of zinc liquid in hot dip galvanizing pot
    HE Tao, LI Bing, LU Yao, WANG Rudong, CUI Heng, XIONG Junwei, ZHANG Yi
    Metallic Functional Materials. 2025, 32(3): 81-90. https://doi.org/10.13228/j.boyuan.issn1005-8192.20240162
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In the continuous hot-dip galvanizing production of strip steel, the flow state and temperature distribution of zinc liquid have a very important impact on product quality, and the flow state and temperature distribution of zinc liquid are closely related to the parameter settings of strip steel and zinc liquid. Taking a continuous hot-dip galvanized aluminum magnesium zinc pot as the research object, uses numerical simulation methods, and establishes a numerical model of zinc liquid flow and heat transfer using the fluid dynamics calculation software Fluent. The accuracy of the model is verified by comparing it with the temperature measurement points provided on site, and the influence of different parameter settings on the flow and heat transfer of zinc liquid in the zinc pot is studied. The results show that increasing the speed of the strip steel can improve the uniformity of the temperature distribution of the zinc liquid, but it also increases the possibility of being rolled into the slag phase; When the temperature of the inlet plate is too low, there is less heat input, which increases the heating pressure of the induction heater. When the temperature of the inlet plate is too high, the solubility of iron element increases and the slag phase increases, which is not conducive to galvanizing work; The initial temperature of zinc solution can significantly affect the temperature distribution of zinc solution. When the initial temperature of zinc solution is set between 450-460 ℃, the temperature distribution of zinc solution is more uniform, which is beneficial for galvanizing.
  • Surface defect detection of NdFeB based on FFA-YOLO
    LI Junfeng, CHEN Qian, HAO Jingbo, DU Yang, LIANG Zhen
    Metallic Functional Materials. 2025, 32(3): 91-96. https://doi.org/10.13228/j.boyuan.issn1005-8192.20240164
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    FFA-YOLO, an efficient detection method, addresses the challenge of complex background interference in surface defect detection for sintered NdFeB products. First, FFA-Net is introduced in the backbone network module to denoise the images. Second, the SEAM module is applied in the neck network layer, where depthwise separable convolution is employed to learn the correlation between spatial dimensions and channels, thus improving detection performance under complex backgrounds. Finally, the C2f_DSConv module is proposed, which adaptively focuses on elongated and tortuous local structures to enhance the accuracy of image segmentation. Experimental results demonstrate that, compared to the baseline model, this model improves mAP@0.5 and mAP@0.5∶0.95 by 3% and 6.6%, respectively, on the sintered NdFeB dataset. The model size is 49.6 MB, and the GFLOPs is 78.7, achieving a significant improvement in detection performance while maintaining the lightweight parameters of the baseline model.
  • Influence of segmented processing on eddy current heating and magnetic properties of sintered Nd-Fe-B magnets
    ZHANG Qingji, SHI Bingqiang, WANG Pengfei, ZHANG Yumeng, WANG Cong, YAN Xiulong, DENG Cong
    Metallic Functional Materials. 2025, 32(3): 97-102. https://doi.org/10.13228/j.boyuan.issn1005-8192.20240165
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    The magnet was segmented along the length direction and divided into N equal parts of penetrating magnets and without penetrating magnets based on the number of segments and whether they were penetrated in the width direction. By measuring the magnetic flux, it is found that for the 4/6/8-equal-part non-penetrated magnets, as the number of segments increases, the volume loss of the maget increased from 0.96% to 2.24%, resulting in an increase in magnetic flux loss from 1.12% to 2.18%;According to the irreversible loss test results at 110,130,150 ℃, the irreversible loss levels of magnets with different numbers of segments at different temperatures are basically the same, fluctuating within the ranges of 0.4%-0.6%, 0.8%-0.88%, 9%-12%, etc. This indicates that segmented processing has a relatively small impact on the irreversible loss of magnets. Setting the magnets in an alternating magnetic field for 10 minutes to simulate the operating environment of the magnet. As the number of segments increases, the temperature rise amplitude of the magnet gradually decreases, the results indicate that the segmented processing without penetration has a significant inhibitory effect on the eddy current effect of the magnet in an alternating magnetic field, with temperatures of 27.5, 26.5 and 25.0 ℃, respectively. By simulating the eddy current loss and motor efficiency of the magnet with and without a 6-section through the section, it was found that the eddy current loss of the magnet without a section through the section was 9.68 W, slightly higher than that of the magnet with a section through the section of 4.95 W, while the motor efficiency was 97.40%, slightly lower than that of the magnet with a 6-section through the section of 97.46%. However, considering that the processing of the magnet without a section through the section can reduce the subsequent adhesive cost and the processing process after adhesive bonding, thus saving costs, the magnet without a section through the section has great potential for reducing eddy current loss.
  • Preparation and development of stainless steel heavy-duty anti-corrosion powder coating on the surface of rail vehicles
    XING Hongnan
    Metallic Functional Materials. 2025, 32(3): 103-108. https://doi.org/10.13228/j.boyuan.issn1005-8192.20240179
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Rail vehicles operating in environments containing electrolytes for a long time are prone to electrochemical corrosion problems such as pitting and crevice corrosion under the combined action of tensile stress and corrosive media. Due to the inability of current coatings to meet the long-term operation needs of rail vehicles in electrolyte containing environments, and the permeability of corrosive media to substrates, coatings fail prematurely, reducing the service life of trains. Therefore, this paper prepares a heavy-duty anti-corrosion powder coating by mixing phenolic modified epoxy resin and epoxy resin, combined with multiple external additives. By changing parameters such as epoxy equivalent, zirconium phosphate content, and curing agent ratio, the apparent properties, mechanical properties, and corrosion resistance of the coating are tested and analyzed. By comparing the coating performance under different parameters, the coating formula is optimized to obtain the best anti-corrosion effect. This coating has excellent apparent and mechanical properties at 950 eq epoxy base equivalent. Under the conditions of a zirconium phosphate addition of 15% and a curing agent to epoxy resin ratio of 1∶5, the coating exhibits good corrosion resistance and impact resistance. These results indicate that the coating can meet the anti-corrosion requirements of the stainless steel body surface of rail vehicles. Based on this paper, the anti-corrosion, weather resistance, and wear resistance of coatings can be further optimized to meet more complex and harsh usage environments.
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