The Nonferrous Metals Society of China

19 June 2026, Volume 36 Issue 6
    

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    MATERIALS SCIENCE AND ENGINEERING
  • Progress in stress-relieving methodologies of ceramic matrix composites/ Ni-based superalloys joints: A review
    Ying-xin WANG, Fu WANG, Qiang YANG, Di-chen LI, Zai-wang HUANG, Yun-song ZHAO, Jian-tao WU
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1685-1711. https://doi.org/10.1016/S1003-6326(26)67055-0
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Ceramic matrix composites (CMCs) are regarded as promising high-temperature materials for industrial applications due to their exceptional properties at elevated temperatures. However, their limited manufacturability restricts their capability to be produced as complex, large-scale structural components. Ni-based superalloys are well-known for their outstanding performance under high-temperature conditions. The integration of these two material types to create hybrid components can significantly broaden their applications in engineering. A critical challenge arises from the interfacial residual stresses that develop at the joints of CMCs and Ni-based superalloys, which can severely impair the performance of the hybrid components. The mechanisms behind the formation of residual stress in CMCs/Ni-based superalloys joints are reviewed, including thermal expansion coefficient (CTE) mismatch, thermal gradient difference, and phase transformation, and various methodologies for alleviating these stresses are summarized, including interlayer techniques, composite filler approaches, and interface structure design strategies. Finally, the challenges and future trends in mitigating interfacial stress in CMCs/Ni-based superalloys joints are discussed.
  • Constructing porosity database for Al−Si alloy castings through 3D cellular automata model and machine learning
    Qing-huai HOU, Xue-long WU, De-cai KONG, Hai-bo QIAO, Xiao-ying MA, Xiang CI, Wen-bo WANG, Yu-ling LANG, Shi-wen XU, Zhong-yao LI, Yi-sheng MIAO, Xing-xing LI, Jun-sheng WANG
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1712-1728. https://doi.org/10.1016/S1003-6326(26)67056-2
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    A coupled three-dimensional cellular automata (CA) model has been used to predict the hydrogen porosity in an Al−Si alloy as a function of thermal boundary conditions. By quantifying the porosity distribution from simulations, a porosity defect database was established, representing a cooling rate ranging from 0.25 to 50 °C/s at an initial hydrogen content of 3.0×10−3 mL/g. Based on the database, four machine learning algorithms including support vector machine (SVM), random forest (RF), K-nearest neighbors (KNN), and gradient boosting machine (GBM) were trained and compared for each porosity characteristic to identify the optimal model. For the prediction of porosity percentage, the determination coefficient (R2) and the root mean square error (RMSE) on the test set reached 0.95 and 0.042, respectively. The predicted porosity distribution agreed well with experiments, indicating that the model can be used to map the porosity size in large casting components.
  • Effect of Ca content on mechanical properties and ignition resistance of Mg−Zn−Zr−Ca alloys
    Shi-cheng LI, Ke WANG, Xiao-dong GUO, Hong-yun LI, Jin-xing WANG, Jing-feng WANG, Fu-sheng PAN
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1729-1748. https://doi.org/10.1016/S1003-6326(26)67057-4
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    Mg−6Zn−0.6Zr alloys with varying Ca contents (0, 0.6, 1.2, 1.8 wt.%) were prepared by gravity casting and hot extrusion. The effect of Ca content on the microstructure, mechanical properties, and ignition resistance of Mg−6Zn−0.6Zr alloy was investigated. The results show that Ca addition promotes Ca2Mg6Zn3 phase formation while inhibiting MgZn2 precipitation in as-cast alloys. After homogenization, the MgZn2 phases are nearly dissolved, while numerous Ca2Mg6Zn3 phases remain. During extrusion, the Ca2Mg6Zn3 phases fragment, and MgZn2 nanoparticles precipitate in the matrix. The combination of fine grains and high-density precipitates significantly enhances the strength of the Ca-containing alloys. The Mg−6Zn−0.6Zr−1.2Ca alloy exhibits the best overall mechanical properties, with ultimate tensile strength of 380.1 MPa, yield strength of 360.1 MPa, and elongation of 10.4%. Additionally, the ignition point increases from 556 to 824 °C with rising Ca content due to the formation of a dense CaO−MgO oxide layer.
  • Mechanisms for synergistically enhanced mechanical properties and corrosion resistance in Mg−Al−Sn alloys
    Da-wei WANG, Rui ZHOU, Ya-jie YANG, Xiao-rui DONG, Hai-long JIA, Pin-kui MA, Jin XU, Quan SHAN, Zu-lai LI, Jin-zhu FU, Min ZHA
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1749-1765. https://doi.org/10.1016/S1003-6326(26)67058-6
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    A combination of rare earth (RE) alloying and plastic deformation was employed to improve the comprehensive properties of Mg−3Al−1Sn−0.5Ca−0.2Mn (ATXM) alloys. The results show that the rolled ATXM-0.1RE alloys exhibit remarkable simultaneous improvements in both mechanical strength and corrosion resistance. Specifically, the alloys with Sm, Ce, and Y additions demonstrate yield strengths of 238, 232, and 238 MPa, elongations of 18%, 17%, and 23%, and corrosion rates of approximately 3.4, 2.9, and 1.7 mm/a, respectively. Notably, the rolled ATXM-0.1Y alloy displays the optimal overall properties. The underlying mechanisms involve grain refinement (from ~50 μm to below 5 μm) and alterations in composition, dimension, and arrangement of secondary phases, which contribute to fine-grain strengthening and Orowan strengthening, thereby bolstering mechanical properties. Furthermore, these modifications mitigate the galvanic corrosion and strengthen the protective corrosion product film, resulting in a significantly improved corrosion resistance.
  • Achieving strength−ductility tradeoff in near alpha titanium alloy via multi-stage heat treatment-induced nano-martensite phase transformation
    Yong-sheng WANG, Han XIAO, Jie LI, Hao-wei LIANG, Kun LIU, Yao-ping XU
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1766-1782. https://doi.org/10.1016/S1003-6326(26)67059-8
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    A novel multi-stage heat treatment strategy was developed, consisting of a high-temperature short-duration step and a low-temperature long-duration step, designed to induce nano-martensitic behavior and achieve an optimal strength−ductility balance. Room-temperature tensile stress−strain curves demonstrate that the multi-stage heat-treated alloy exhibits an exceptional synergy between strength and ductility. This improvement arises from the combined effect of recrystallized equiaxed α grains formed during high-temperature step and dispersed nanoparticles generated by the controlled decomposition of nano-martensite (α′) during the low-temperature step. Furthermore, crystallographic analysis based on the Burgers orientation relationship (BOR) reveals variant selection phenomena during the β→α' phase transformation.
  • Effect of Al on microstructure and properties of Cu−Be−Ni alloy processed by thermo-mechanical treatment
    Yan-bin JIANG, Fei WANG, Wei CHEN, Xin-hua LIU, Zhi-hao ZHANG, Xiao-yu JIANG
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1783-1798. https://doi.org/10.1016/S1003-6326(26)67060-4
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    The effects and underlying mechanisms of aging treatment on the microstructure and properties of Cu−0.3Be−2.0Ni and Cu−0.3Be−2.0Ni−0.2Al alloys (subjected to solid solution treatment followed by 70% cold rolling) were investigated. Results showed that the Cu−0.3Be−2.0Ni alloy mainly precipitated the Ni−Be phase, while the Cu−0.3Be−2.0Ni−0.2Al alloy exhibited co-precipitation of both Ni−Be and Ni3Al phases. The combined strengthening from nanoscale Ni3Al and Be−Ni phases significantly increased the strength of the Cu−0.3Be−2.0Ni−0.2Al alloy compared to the Cu−0.3Be−2.0Ni alloy. Thermo-mechanical treatment improved both the hardness and electrical conductivity of the alloys. Compared with conventional aging, the Cu−0.3Be−2.0Ni−0.2Al alloy showed a 13% increase in hardness and a 6.8% increase in electrical conductivity, while the Cu−0.3Be−2.0Ni alloy exhibited a 6% hardness increase with slight conductivity improvement.
  • Microstructure evolution and mechanical properties of bulk nanocrystalline Zn−Cu−Sr−Li alloy processed by high-speed rolling
    Ze-xu YANG, Si-cong ZHAO, Lei WANG, Yi-cheng FENG, Er-jun GUO
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1799-1815. https://doi.org/10.1016/S1003-6326(26)67061-6
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    Nanocrystalline Zn−3Cu−0.2Sr−xLi (x=0, 0.2, 0.4, wt.%) alloys were prepared via high-speed rolling to meet the urgent demand for high-performance alloys in the biomedical field. The high-speed rolling process generated numerous dislocations, providing sufficient driving force for recrystallization. The addition of Li promoted the formation of ε and β phases. These secondary phases provided abundant heterogeneous nucleation sites and a strong pinning effect, facilitating recrystallized grain nucleation while inhibiting its growth. The grain size of the alloy containing 0.4 wt.% Li was refined from 181.8 μm to 50 nm after rolling. The ultimate tensile strength, yield strength, and elongation of the rolled alloy containing 0.4 wt.% Li achieved 433.3 MPa, 389.2 MPa, and 15.2%, respectively. Compared to the as-cast Li-free alloy, 0.4Li alloy demonstrated a 173% increase in yield strength and a 591% improvement in elongation. Nanocrystalline strengthening was the dominant mechanism, contributing 70.4% to the total yield strength of the rolled Zn−3Cu−0.2Sr−0.4Li alloy.
  • Adjusting mechanisms for ultrafine-grained microstructures during hot deformation of Ni−38Cr−3.8Al alloy via pre-ageing precipitation
    Yu-qing ZHANG, Guo-zheng QUAN, Yan-ze YU, Ying-ying LIU, Wei XIONG, Wei-wei DAI, Qian JIANG
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1816-1833. https://doi.org/10.1016/S1003-6326(26)67062-8
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    Five different samples were fabricated via altering pre-ageing temperature to explore the effects of pre-precipitation states on dynamic recrystallization (DRX) and microstructure evolution during hot compression of Ni−38Cr−3.8Al alloy. Results reveal that α-Cr phases precipitate from the matrix in lamella and particle forms during pre-aging treatment. During subsequent hot deformation, the pre-precipitated α-Cr lamellae experience significant dissolution fragmentation and spheroidization, transforming into finer particles due to the elevated temperature and high-density dislocations. At 560 °C, incomplete discontinuous precipitation (DP) state inhibits DRX, leading to necklace-like microstructures. As temperature exceeds 640 °C, complete DP state promotes DRX, resulting in ultrafine-grained microstructures. Coarse α-Cr particles enhance DRX process through particle-stimulated nucleation (PSN) and discontinuous DRX mechanisms, while dissolved α-Cr lamellae promote DRX via continuous DRX mechanism. The DRX kinetics analysis indicates that increasing pre-ageing temperature accelerates DRX, as demonstrated by reduced critical strain and peak strain, and increased DRX volume fraction.
  • Numerical simulation of solidification structure during electron beam smelting process of superalloy ingots
    Li-dan NING, Yi TAN, Peng-ting LI, Ru-sheng BAI, Shu-tao WEN, Geng-yi DONG
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1834-1847. https://doi.org/10.1016/S1003-6326(26)67063-X
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    A mathematical model based on the cellular automaton−finite element (CAFE) method was developed to study the solidification structure evolution of DD98M superalloy ingots during electron beam smelting (EBS). The model couples heat transfer, fluid flow, and solute diffusion. Grain nucleation and growth occur in the direction opposite to the heat flow. The simulation results show good agreement with experimental observations. The influence of the nucleation parameters on the solidification structure was systematically examined. The results indicate that increasing the maximum bulk nucleation density leads to a reduction in grain size and promotes the formation of a larger equiaxed grain region, while simultaneously reducing the extent of the columnar grain region. In contrast, increasing the mean bulk nucleation undercooling results in a smaller equiaxed region and an expanded columnar grain zone. The standard deviation of bulk nucleation undercooling is found to have a negligible effect on grain morphology.
  • High-performance Finemet alloy thin film with amorphous/nanocrystalline structure treated by rapid-thermal process
    Jun-jie LIU, Zhao-guo QIU, Yi-ming ZENG, Zhi-gang ZHENG, Gang WANG, Zhi-peng HOU, Hao-liang LIU, De-chang ZENG, Ping LIU
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1848-1859. https://doi.org/10.1016/S1003-6326(26)67064-1
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    The influence of thickness and annealing treatment on microstructure and soft magnetic properties of Fe−Si−B−Cu−Nb alloy (Finemet) thin films prepared by magnetron sputtering was systematically studied. As the thickness of the film increases, the coercivity decreases while the saturation magnetization increases, and then both reach a stable state. Following annealing at 773 and 873 K, nanocrystalline α-Fe precipitates within the thin film. The exchange coupling effect between nanocrystals and the amorphous matrix significantly enhances the soft magnetic properties of the thin film. Rapid-thermal process controls the heating rate to minimize grain size and optimize nanocrystal distribution, achieving lower coercivity and higher saturation magnetization without necessitating extra transition metals. Consequently, the Fe−Si−B−Nb−Cu thin film subjected to rapid-thermal process at 873 K for 30 min with a heating rate of 25 K/s exhibits low coercivity of 0.8 A/m and high saturation magnetization of 1.45 T.
  • Single crystal NCM811 cathode material prepared by rapid solvothermal method
    Li-xing XUE, Hong-yan PAN, Yu-jie WANG, Wei YANG, Yue-jun WANG, Xiang-nan BU, Qian LIN, Kuo ZHANG, Liang-xing JIANG
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1860-1874. https://doi.org/10.1016/S1003-6326(26)67065-3
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    To achieve large-scale application of solvothermal method and settle structural collapse of polycrystalline ternary NCM cathode materials (LiNi0.8Co0.1Mn0.1O2, NCM811) during long charge and discharge cycling, single-crystalline NCM materials with high cycling stability were prepared by rapid ethanol−water solvothermal method. The morphology and electrochemical properties of NCM materials were characterized by X-ray diffractometry, cross-section scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and electrochemical measurement. The results show that single-crystalline NCM synthesized with 60 min solvothermal time has the most excellent electrochemical performance. Its reversible capacity reaches 157.28 mA·h/g at 1C and retention rate achieves 55.06% after 200 cycles, which is much better than the polycrystalline NCM cathode material. Cross-section scanning electron microscopy results show that the single-crystalline NCM cathode material has no apparent cracks after 200 cycles.
    • Mining, Minerals Processing and Metallurgical Engineering
  • Effects of oxidation roasting on surface characteristics and flotation behavior of bastnaesite
    Qiang ZHANG, Yong-sheng SUN, Zhao CAO, Peng GAO, Wen-bo LI
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1875-1890. https://doi.org/10.1016/S1003-6326(26)67066-5
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    The effect of oxidation roasting on the surface characteristics and flotation behavior of bastnaesite was investigated. Oxidation roasting experiments were performed at various temperatures, time, and O2 concentrations. The results indicated that increasing the temperature promoted the thermal decomposition of bastnaesite, resulting in the formation of Ce7O12, RE2O3, and REF3 as the main phases. Furthermore, oxidation roasting induced the formation of long, narrow, and nearly parallel cracks within the particles, increasing the porosity and facilitating partial particle fragmentation. During flotation, the concentration of dissolved rare earth ions increased significantly, and surface hydrolysis led to the formation of rare earth hydroxyl compounds. The complete decomposition of bastnaesite increased the required collector dosage to achieve a recovery above 85.00%. This increase might be attributed to the enhanced particle wettability, the altered adsorption mechanism of the collector, and the deeper penetration of the collector into the porous structure.
  • Low-ammonium synergistic leaching of ionic rare earth ore with acetic acid−ammonium sulfate system
    Shan HU, Lian-jun WU, Jun WANG, Yang LIU, Bing-xuan HE, Guan-zhou QIU
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1891-1902. https://doi.org/10.1016/S1003-6326(26)67067-7
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    To mitigate ammonium pollution and soil acidification associated with traditional (NH4)2SO4 leaching of ionic rare earth ores, a synergistic approach utilizing low-concentration (NH4)2SO4 and acetic acid (HAc) was proposed to enhance ion exchange efficiency while minimizing ammonium consumption. Leaching efficiency and ammonium consumption were evaluated through comparative leaching experiments. Under optimized co-leaching conditions (pH 4−5, 30 °C, and 1 h), rare earth elements (REEs) leaching efficiency of 88.92% was achieved. This represents a  13.36% increase over single (NH4)2SO4 leaching (0.02 mol/L). Compared to the conventional single (NH4)2SO4 system (requiring 0.03 mol/L for 90% efficiency), ammonium consumption was reduced by 33.3%. Characterization revealed enhanced surface roughness and significantly increased negative charge on the ore in the synergistic system, facilitating RE3+ exchange. This study provides a sustainable leaching approach, reducing the environmental impact of traditional REE extraction through the rational use of inorganic lixiviants.
  • Efficient separation of heavy metals from gypsum residue and secondary zinc oxide fume based on synergistic sulfidation
    Yong-wei WANG, Rui HUANG, Wen-qing QIN, Jun-wei HAN
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1903-1920. https://doi.org/10.1016/S1003-6326(26)67068-9
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    Synergistic sulfidation roasting of heavy metal gypsum residue and secondary zinc oxide fume was proposed by using the research idea of “waste to treat waste”. Thermodynamic studies indicated that the sulfidation of zinc oxide could be effectively enhanced by increasing the dosage of calcium sulfate and carbon powder in the range of 500−800 °C. The synergistic sulfidation experiments of heavy metal gypsum residue with secondary zinc oxide showed that the sulfidation rate of zinc reached 90.39% and the grain size of ZnS increased from 5 to 10 μm under the conditions of temperature 700 °C, carbon powder 30%, Na2CO3 10%, mass ratio of gypsum residue to secondary zinc oxide 1.4꞉1, roasting time 2 h and cooling rate 1 °C/min. Meanwhile, 76.32% F, 72.11% Cl and 93.41% As were removed. TG/DTG−DSC, 3D FTIR spectra and SEM analysis showed that the conversion of CaSO4 to CaCO3 and the avoidance of CO2 and SO2 production were achieved under optimized conditions. This study achieves efficient sulfidation of zinc as well as growth of ZnS grains, laying the theoretical and technological foundation for subsequent recovery of ZnS by flotation.
  • Assessment of zinc migration behavior and toxicity characteristics in redox smelting of zinc leaching residue
    Heng WANG, Cheng TAN, Yong YU, Rui-jin FAN, Jian-hang HU, Hua WANG
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1921-1933. https://doi.org/10.1016/S1003-6326(26)67069-0
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    The effects of key redox smelting parameters, including anthracite addition amount, temperature, and holding time, on Zn migration behavior and toxicity characteristics were investigated. The results showed that CaSO4 in leaching residue promoted the transformation of ZnFe2O4 into ZnS−FeS eutectic, hindering Zn recovery and contributing to contamination potential. At temperatures above 1573 K, the ZnS−FeS eutectic in the upper slag was oxidized by O2/(O)slag to form ZnO(s), then converted to chemically dissolved Zn, and finally reduced to Zn(g) by CO. Zn volatilization can be improved by pre-desulfurization or by increasing the oxygen potential. Under optimized conditions, the Zn residual content decreased to 0.22 wt.%, substantially lower than the industrial range of 1.0−3.0 wt.%, thereby reducing environmental hazards.
  • CFD modeling of gas−liquid mixing and splashing in industrial-scale bottom-blowing furnace: Effects of melt viscosity
    Cheng-lin LI, You YAN, Ao HAO, Wei-wen HU, Zi-lin YANG, Dong-ling WU, Liu LIU, Hong-jie YAN
    Transactions of Nonferrous Metals Society of China. 2026, 36(6): 1934-1948. https://doi.org/10.1016/S1003-6326(26)67070-7
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    The effects of high-lead slag viscosity on gas−liquid mixing efficiency, splashing behavior, and furnace lining erosion were investigated in an oxygen bottom-blowing lead smelting process incorporating lead-containing waste materials. A multi-fluid volume of fluid (VOF) model, integrating experimentally determined slag viscosity values, was used to examine these interactions. The results indicated that optimal gas−liquid mixing occurred at viscosity values of 0.01 and 0.5 Pa·s, while minimal splashing was observed within the viscosity range of 0.1−0.25 Pa·s, corresponding to temperatures of approximately 1076−1100 °C. The regions surrounding the oxygen lances were most susceptible to erosion. Shear stress increased with an increase in melt viscosity, particularly rapidly in the viscosity range of 0.1−0.25 Pa·s. It was recommended that the melt viscosity should be maintained within 0.01−0.1 Pa·s to minimize erosion.
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