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Effect of prolonged natural ageing on microstructure and tensile properties of a high strength die-cast Al-Mg-Si-Zn alloy

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Journal of Alloys and Compounds 2025年 1032卷

作者： Han, Qixiu Dong, Xixi Liu, Qian Yang, Hailin Ji, Shouxun College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing210016 China State Key Laboratory of Advanced Forming Technology & Equipment Nanjing University of Aeronautics and Astronautics Nanjing210016 China State Key Laboratory of Powder Metallurgy Central South University Changsha410083 China Brunel University London UxbridgeUB8 3PH United Kingdom

A two-year prolonged natural ageing effect of a high strength and heat treatment-free Al5.5Mg2Si3Zn die-cast alloy was investigated, and the microstructure was characterized to understand the underlying mechanisms of high strength in the as-cast state and the strong natural ageing strengthening. The die-cast alloy exhibited the high yield strength (YS) of 211 ± 2.3 MPa, ultimate tensile strength (UTS) of 334.7 ± 14.4 MPa and the good elongation (EL) of 5.8 ± 1.28 % in the initial as-cast state. After natural ageing for 24 months, the die-cast alloy delivered the high YS of 290.9 ± 2.7 MPa, UTS of 375.3 ± 6.8 MPa and the industrially acceptable EL of 2.58 ± 0.24 %, which shows 38 % improvement in YS over the die-cast alloy under as-cast condition. The intrinsic connection between the YS and the natural ageing time of 24 months can be expressed as an exponential model, i.e., YS (MPa)= 291.83–71.93 × 0.99t (day). The YS reached a stable state after natural ageing for 8.3 months. The as-cast alloy comprised the intermetallic phases of Mg2Si, α-Fe and Mg32(Al, Zn)49. The diameter of the fibrous Mg2Si phase ranged from 0.08 to 0.25 μm, while the size of the fine blocky α-Fe was measured as ∼0.8 μm. Strengthening by refined primary and secondary phases and solid solution are responsible for the high as-cast YS over 200 MPa. The precipitation strengthening of nanoscale η'-MgZn2 precipitates with the number density of 23.6 × 1023, 36.5 × 1023 and 44.8 × 1023/m2 contributed to the strong enhancement of 34.2, 68.0 and 79.8 MPa over the as-cast YS after natural ageing for 1, 7.2 and 24 months, respectively. © 2025 Elsevier B.V.

关键词： Tenacity

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Microstructure and high-temperature wear behavior of TiZrNbAl x light-weight refractory high-entropy alloy coatings prepared by laser cladding on Ti6Al4V titanium alloy

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Surface and Coatings technology 2025年 512卷

作者： Yaxia Liu Hongxi Liu Yang Chen Ming Wen Ben Niu Xiaowei Zhang Haifang Liu The Faculty of Materials Science and Engineering Kunming University of Science and Technology Kunming 650093 China National-local Joint Engineering Research Center for Technology of Advanced Metallic Solidification Forming and Equipment Kunming 650093 PR China State Key Laboratory of Precious Metal Functional Materials Kunming Institute of Precious Metals Kunming 650106 China China-Ukraine Institute of Welding Guangdong Academy of Sciences Guangdong Provincial Key Laboratory of Material Joining and Advanced Manufacturing Guangzhou 510650 China

The TiZrNbAl x (x = 0.1, 0.2, 0.3) light-weight refractory high-entropy alloys coatings were fabricated on the Ti6Al4V titanium alloy by laser cladding technology. The effect of Al content on the microstructure and wear behavior of the coatings were investigated. All coatings were composed of the BCC phase and a few Zr-rich phase. The grains were refined as the Al content increased, and the Zr-rich phase increased. The TiZrNbAl 0.3 exhibited the best wear resistance at room temperature and 500 °C. Compared to Ti6Al4V, the wear rate of TiZrNbAl 0.3 decreased by 48.54 % and 15.7 % at room temperature and 500 °C, respectively. Molecular dynamics simulations were used to study the wear behavior of TiZrNbAl 0.3 coating at different temperatures, and the results showed that the thermal vibrations and random motion of the interface atoms are enhanced at 500 °C, weakening the crystalline characteristics of the interface, promoting strain accumulation in the TiZrNbAl 0.3 coating, and further worsening the material wear. As a result, the wear resistance of the coatings at 500 °C is lower than at room temperature.

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Comprehensive insights into electrical properties enhancement of boron‑sulfur co-doped diamond via ion implantation: First principles calculation and experimental validation

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Diamond and Related Materials 2025年 157卷

作者： Wang Zhao Bing Wang Zhanqiang Liu Honglu Li Zhaoliang Yu Pengyang Wang School of Mechanical Engineering Shandong University Jinan 250061 PR China Shandong Key Laboratory of High Performance Tools and System Jinan 250061 PR China Key Laboratory of High Efficiency and Clean Mechanical Manufacture of Ministry of Education Jinan 250061 PR China State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Jinan 250061 PR China Department of Computer and Information Science University of Macau PR China

Diamond presents great potential for applications as high‑temperature and high-power electronic devices as a new generation of semiconductor material. However, the inherent low electrical conductivity limits diamond applications. This study aims to reveal the conductive mechanism of boron (B)‑sulfur (S) co-doped diamond for conductivity enhancement with density-functional theory (DFT) calculations and ion implantation experiments. Firstly, the effects of B-S co-doping on diamond's electrical properties are investigated by analyzing the band structure and electron transport at different doping ratios using DFT. Secondly, Precision doping into single-crystal diamond is achieved via ion implantation, followed by annealing to remove lattice defects. Thirdly, the lattice integrity after doping is assessed by Raman spectroscopy, the chemical compositions and bonding states are analyzed by X-ray photoelectron spectroscopy, and the electrical properties of the co-doped diamonds are evaluated by Hall effect measurements. First-principles calculations show that B-S co-doping also generates additional acceptor and donor energy levels that couple, leading to more uniformly distributed impurity levels, a narrower band gap, altered electron transitions, and coupling in specific orbitals. These modifications imply that a B:S co-doping ratio of 1:2 may be favorable for enhanced carrier activation and improved electrical transport behavior. Based on first-principles calculations and Hall effect experiments the optimal conductivity occurs at a B:S ratio of 1:2, which gives better conductivity compared to single doping or other ratios. These findings Preliminary provide complementary theoretical and experimental evidence supporting the modulation of electrical conductivity through B-S co-doping.

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The Effect of Aging Treatment on Microstructure and Corrosion Resistance of 7××× Series Aluminum Alloy

The Effect of Aging Treatment on Microstructure and Corrosio...

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Artificial Intelligence and Electromechanical Automation (AIEA), International Conference on

作者： Chunming Li Feng Zhang Yong Yang Yunbo Chen Lingli Zuo Yang Zhang Lin Chen State Key Laboratory of Advanced Forming Technology and Equipment Beijing National Innovation Institute of lightweight Ltd Beijing Anhui Fenghui Metal Co. Ltd. Fuyang

ISBN: (数字)9781728182889

ISBN: (纸本)9781728182896

the influence of aging treatment on the microstructure and corrosion resistance of 7××× series aluminum alloy was studied by means of microstructure analysis, energy spectrum analysis, tensile test and intergranular corrosion test. The results show that the tensile strength, yield strength and elongation of alloy after peak-aging (121°C / 24 h) treatment are 605.3 MPa, 501.9 MPa and 8.6%, respectively, but which corrosion resistance is the worst; the strength of over-aged (121°C / 6 h + 177°C / 8 h) is significantly lower than that of peak-aging, but it has highest elongation, reaching 11.9%, besides, its corrosion resistance is the best; the strength of interrupted ageing (121°C / 0.5 h (water cooling) + 65°C / 240 h + 121°C / 24 h) alloy is the highest, and the corrosion resistance is better than those of peak-aging.

关键词： 7 ××× aluminum alloy aging treatment corrosion resistance corrosion resistance ageing treatment Microstructure aluminium alloys peaks

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[email protected] Ti 3 C 2 T x @Ni particles with enhanced microwave absorption properties and prolonged stability

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Materials Research Bulletin 2023年 164卷

作者： Weimin Xu Shibo Li Weiwei Zhang Shujun Hu Wenbo Yu Yang Zhou Center of Materials Science and Engineering School of Mechanical and Electronic Control Engineering Beijing Jiaotong University Beijing 100044 China State Key Laboratory of Advanced Forming Technology and Equipment Beijing National Innovation Institute of Lightweight Ltd. Beijing 100083 China

2D Ti 3 C 2 T x MXene with a multi-layered structure and surface functional groups exhibits an ability to attenuate electromagnetic energy through the dielectric loss mechanism. However, the absence of magnetic properties causes its unmatched impedance and poor MA performance. In addition, as exposed to air, oxidization of Ti 3 C 2 T x generally starts from its nanosheet edges and gradually expands to the inside, causing severe oxidative degradation within days and thus restricting its industrial applications. Here, [email protected] structured Ti 3 C 2 T x @Ni particles were prepared by electroless plating. The plated thinner Ni(P) shell endows the modified Ti 3 C 2 T x particles with good impedance matching with microwaves. A minimum reflection loss (RL min ) value of -48.34 dB was achieved in the Ti 3 C 2 T x @Ni particles, better than the RL min of ∼ -11 dB for the pristine Ti 3 C 2 T x . The [email protected] Ti 3 C 2 T x @Ni particles are particularly attractive in its storage stability. As compared with the fast and oxidation of Ti 3 C 2 T x within 12 weeks, the as-prepared Ti 3 C 2 T x @Ni particles are stable up to a year in air because the Ni shell prevents Ti 3 C 2 T x nanosheets from oxidative degradation.

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A Model for Predicting Dynamic Cutting Forces in Sand Mould Milling with Orthogonal Cutting

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Chinese Journal of Mechanical Engineering 2018年第6期31卷 95-105页

作者： Zhong-De Shan Fu-Xian Zhu State Key Laboratory of Advanced Forming Technology and Equipment China Academy of Machinery Science TechnologyBeijing 100083China Jiangsu University of Technology Changzhou 213001China

Cutting force is one of the research hotspots in direct sand mould milling because the cutting force directly a ects the machining quality and tool wear. Unlike metals, sand mould is a heterogeneous discrete deposition material. There is still a lack of theoretical research on the cutting force. In order to realize the prediction and control of the cut?ting force in the sand mould milling process, an analytical model of cutting force is proposed based on the unequal division shear zone model of orthogonal cutting. The deformation velocity relations of the chip within the orthogonal cutting shear zone are analyzed first. According to the flow behavior of granular, the unequal division shear zone model of sand mould is presented, in which the governing equations of shear strain rate, strain and velocity are estab?lished. The constitutive relationship of quasi?solid–liquid transition is introduced to build the 2D constitutive equation and deduce the cutting stress in the mould shear zone. According to the cutting geometric relations of up milling with straight cutting edge and the transformation relationship between cutting stress and cutting force, the dynamic cutting forces are predicted for di erent milling conditions. Compared with the experimental results, the predicted results show good agreement, indicating that the predictive model of cutting force in milling sand mould is validated. Therefore, the proposed model can provide the theoretical guidance for cutting force control in high e ciency mill?ing sand mould.

关键词： Green manufacture Cutting force Sand mould milling Orthogonal cutting Quasi?solid–liquid transition

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Solid-particle erosion resistance of NbC-reinforced AlCrFeNi medium-entropy alloy at ambient and elevated temperatures

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Wear 2025年 570卷

作者： Xu, Zhen He, A. Tang, Yunqing Chen, keyang Diao, Guijiang Wu, Mingyu Fraser, Doug Li, Jing Chung, Rei Fang, Ranran Vorobyev, Anatoliy Chen, D.L. Li, D.Y. Department of Chemical and Materials Engineering University of Alberta EdmontonABT6G 2H5 Canada State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Jinan250061 China Trimay Wear Plate Ltd 4805 82 Ave NW EdmontonABT6B 0E5 Canada Suncor Energy Inc 150 6 Ave SW CalgaryABT2P 3E3 Canada School of Optoelectronic Engineering Chongqing University of Posts and Telecommunications Chongwen Road Nanan District Chongqing400065 China Department of Mechanical Industrial and Mechatronics Engineering Toronto Metropolitan University TorontoONM5B 2K3 Canada Shi-changxu Innovation Center for Advanced Materials Institute of Metal Research Chinese Academy of Sciences Shenyang110016 China

High-entropy alloys (HEAs) and medium-entropy alloys (MEAs) containing passive elements, such as Al and Cr, exhibit good resistance to high-temperature oxidation due to the formation of protective Al2O3 or Cr2O3 oxide scales. The cost-effective AlCrFeNi alloys have demonstrated impressive mechanical properties, attracting considerable attention. In this study, NbC particles in various amounts (10, 20, 30, 40, and 60 wt%) were added to the AlCrFeNi alloy via arc melting to fabricate MEA-matrix composites. The microstructure, mechanical properties, and resistance of the NbC-added AlCrFeNi composites to air-jet sand erosion at both ambient temperature (20 °C) and elevated temperature (500 °C) were investigated. To better evaluate the NbC-AlCrFeNi composites, two commercial materials, high-Cr cast iron (HCCI) and Ni superalloy (Inconel HX), were also tested for comparison. The results demonstrated that the addition of NbC significantly enhanced the erosion resistance of the alloy. Samples containing 40–60 wt% NbC exhibited superior erosion resistance compared to the reference alloys at both 45° and 90° impact angles. The increased hardness, good toughness, and oxidation resistance of the NbC-added AlCrFeNi alloys contributed to their enhanced erosion resistance. This study highlights the potential of AlCrFeNi as a metal matrix for developing high-performance metal-matrix composites (MMCs). © 2025 The Authors

关键词： Metallic matrix composites

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A review of recent research on bionic structural characteristics and performance mechanisms of biomimetic materials

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Composites Part B: Engineering 2025年 304卷

作者： Wang Haipeng Li Shaomin Zhou Qijie Peng Haichun Liu Xiaolin Shao Zhenyu Song Peng Key Laboratory of High-efficiency and Clean Mechanical Manufacture of MOE School of Mechanical Engineering Shandong University Jinan 250061 China State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Jinan 250061 China Institute of Aerospace Special Materials and Processing Technology HIWING Technology Academy of CASIC Beijing 100074 China Institute of Bionic and Micro-Nano Systems Beihang University Beijing 100191 China Aerospace Times Feihong Technology Company Limited Beijing 100094 China

Lightweight structures with high energy absorption (EA) performance are of great significance in many crucial fields. Biomimetic structural design has demonstrated an effective strategy to improve the performance of both materials and structures by incorporating the unique structural characteristics of natural organisms. This review paper provides an in-depth and comprehensive overview of some important advances in structural design to obtain novel bio-inspired structures with improved energy absorption properties. The structural designs are categorized and summarized based on the common characteristics of biomimetic structures and their bio-inspired sources, and detailedly introduced in terms of the structural configurations, manufacturing processes, analysis methods and energy absorption properties as well as the comparative analysis of performance indicators. Moreover, the application investigations of biomimetic lightweight structures across diverse engineering domains are explored. The introduction of biomimetic structural characteristics indeed significantly improved the structural energy absorption performance and crashworthiness while maintaining the similar overall weight. This phenomenon drives many researchers to devote themselves to this investigations, and continuously achieve new research results. Meanwhile, the endless variety of biological species in nature provides inexhaustible sources for biomimetic structural designs. However, most of these investigations stop at laboratory and are difficult to achieve actual applications due to their various limitations such as manufacturing processes, serviceability in specific environments, the cost of innovative materials and production, product maturity, and the feasibility and cost of mass production. In short, the biomimetic lightweight structures present great potential and broad application prospects, but there are still many challenges to the practical applications.

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Theoretical modelling for accurate prediction of transient rapid temperature rise variation within whole tool tip area

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Applied Thermal Engineering 2025年

作者： Lirui Zheng Jinfu Zhao Zhanqiang Liu Bing Wang Xiaoping Ren Pengyang Wang School of Mechanical Engineering Shandong University China State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Jinan 250061 China Key Laboratory of High Efficiency and Clean Mechanical Manufacture of Ministry of Education Shandong University Jinan 250061 China Key National Demonstration Center for Experimental Mechanical Engineering Education Shandong University Jinan 250061 China School of Mechanical Electrical & Information Engineering Shandong University Weihai 264209 China Faculty of Science and Technology University of Macau Macau E11 China

Cutting temperature modelling aids in the prediction of cutting tool wear. Previous studies have focused on steady state cutting temperature modelling and evaluation, neglecting the prediction performance of the temperature variation at the initial cutting stage, where the cutting temperature rises rapidly and the quasi-steady-state is reached quickly. This research develops a two-dimensional tool tip transient cutting temperature model based on the finite volume method (FVM) with a structured grid but without grid-generation computation. This model comprehensively considers nonlinear heat conduction and tool rake face jet cooling. The proposed models with different assumptions of tool flank face boundary conditions are verified by a high-speed infrared (IR) camera. The isothermal tool flank face assumption best simulates the time for the cutting temperature to reach a steady state ( t st ), with a mean absolute error (MAE) of 4.40 ms. The strong convection tool flank face assumption can predict temperature variations during the initial cutting stage, with a minimum mean absolute percentage error (MAPE) of 20.31 %. The influence mechanisms of the tool flank face convection heat transfer coefficient assumption and cutting speed (the main factors influencing temperature) on the model solution are discussed. The results show that the simulated steady state temperature and t st decay in a double-exponential summation form with the increase of the tool flank face convection coefficient. A high cutting speed induces a higher steady state temperature, but t st is reduced to a decay limit.

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Optimization of Casting Process of Headstock Based on Numerical Simulation

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Journal of Physics: Conference Series 2021年第2期1802卷

作者： Yifei Wang Zhongde Shan Haoqin Yang Xueliang Zhang Mengmeng Zhao State Key Laboratory of Advanced Forming Technology and Equipment China Academy of Machinery Science and Technology Group Co. Ltd Beijing 100083 China

In this paper, the casting process optimization design of a certain type of headstock is carried out by numerical simulation technology of casting process. Designed the pouring plan based on theoretical calculation; based on the numerical simulation results, quantitatively designed the riser size, and rationally arranged the pouring riser system based on the equilibrium solidification theory, which can reduce the shrinkage porosity and shrinkage defects in the casting process and increase the process yield; Finally, a sand core production plan is provided based on the precision machining technology of the moldless casting mold, which provides a new idea for the process plan design of complex spindle box castings.

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