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Effect of CNT content on microstructure and tribological properties of CNTs/AlSi10Mg composites by LPBF

China Foundry 2025年 1-10页

作者： Jiang, Li-Yi Shen, Chao-Yi Liu, Ting-Ting Zhang, Chang-Dong Su, Xiang Xu, Wei-Wei Wang, Bo-Xiang Qi, Zhi-Xiang Liao, Wen-He School of Mechanical Engineering Nanjing Institute of Technology Nanjing 211167 China National Joint Engineering Research Center of NC forming technology and equipment School of Mechanical Engineering Nanjing University of Science and Technology Nanjing 210094 China Jiangsu Belight Laboratory State Key Laboratory of Advanced Casting Technologies Nanjing University of Science and Technology Nanjing 210094 China School of Aviation and Mechanical Engineering Changzhou Institute of Technology Jiangsu Changzhou 213032 China

In this study, carbon nanotubes (CNTs)/AlSi10Mg composite parts with CNTs contents ranging from 0.0 to 2.0wt.% were successfully fabricated via laser powder bed fusion (LPBF) with laser scan speeds ranging from 900 to 1,900 mm·s−1. Uniform dispersion of CNTs in the powders can be achieved when their content is below 2.0wt.%. In the LPBF samples, the morphology of the CNTs is found to be directly related to their content. Especially, the length of CNTs in samples prepared by LPBF increases as the CNT content increases. The length of CNTs is approximately 200–300 nm in the 1.0wt.% CNTs/AlSi10Mg composites and approximately 500–1,000 nm in the 2.0wt.% CNTs/AlSi10Mg composites. The hardness of the composites reaches its highest value of 143.3 HV when the CNTs content is 1.0wt.% and the laser scan speed is 1,300 mm·s−1. It is found that the self-lubricating properties of the CNTs improve the tribological properties of the composites. The coefficient of friction (CoF) and wear rate of the samples decrease with increasing CNT content. At a CNTs content of 2.0wt.%, the CoF and wear rate of the composite decrease by approximately 14% and 30%, respectively, compared to the unreinforced matrix. The presence of CNTs leads to a more complete and refined network microstructure within the samples. Both the CNTs and the aluminum carbide contribute to the Orowan mechanism and the Hall-Petch effect within the matrix. © Foundry Journal Agency 2025.

关键词： A aluminum matrix composites carbon nanotubes (CNTs) coefficient of friction (CoF) hardness laser powder bed fusion (LPBF) TG146.21

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Melting behavior of VNbMoTa particle and its influence on microstructure and mechanical properties of laser additively manufactured nickel matrix composites

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Journal of Materials Research and technology 2025年 36卷 8698-8710页

作者： Shang Sui Jiawei Qi Dong Ma Chunjie Xu Can Guo Xiangquan Wu Zhongming Zhang School of Materials Science and Engineering Xi'an University of Technology Xi'an Shaanxi 710048 China Xi'an Shechtman Nobel Prize New Materials Institute Xi'an Shaanxi 710048 China Xi'an Key Laboratory of Advanced Magnesium Alloy Additive Manufacturing and Precision Forming Xi'an Shaanxi 710048 China

The currently used reinforcing particles in the additively manufactured nickel matrix composites (NMCs) are limited to non-deformable particles, largely restricting the advancement of novel composite materials. High entropy alloy is a kind of reinforcing particles possessing tremendous potential, however, its application in NMCs has not been realized hitherto. In this work, the ductile VNbMoTa is chosen as the reinforcing particle, and the feasibilities of its employment in two printing processes (laser directed energy deposition, LDED and laser powder bed fusion, LPBF) of Inconel 625 are investigated in detail. The numerical simulation is used to compute the melt pool morphology and the melting time of the VNbMoTa particle. The results demonstrate that the VNbMoTa particles are completely melted in the LDED process, while preserved in the LPBF process, which is ascribed to the longer time for melting offered in the former melt pool. Additionally, the unmelted VNbMoTa particles are conducive to refining grains and inducing equiaxed grain formation, while the fully melted VNbMoTa particles have little effect on grain structure. The main reason lies in the fact that the unmelted VNbMoTa particles can enhance the heterogenous nucleation to induce more new grains formation and hinder the movement of the grain boundary to suppress the grain coarsening. The LPBF-processed NMCs demonstrate excellent strength-ductility synergy with the yield strength of 1083.7 ± 19.3 MPa and the elongation of 12.1 ± 2.2 %. The hetero-deformation induced strengthening effect caused by the ductile VNbMoTa particles attributes to the outstanding yield strength of the LPBF-processed NMCs.

关键词： Laser directed energy deposition Laser powder bed fusion Nickel matrix composites High entropy alloy Microstructure Mechanical properties

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Bauschinger effect in nano-grinding of 3C-SiC: A molecular dynamics study

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Wear 2025年

作者： Zhao, Xiangyang Tang, Yunqing Chen, keyang Cai, Yukui Liang, Xiaoliang Liu, Zhanqiang Li, Dongyang School of Mechanical Engineering Shandong University Jinan250061 China State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Jinan250061 China Key Laboratory of High Efficiency and Clean Mechanical Manufacture of Ministry of Education Jinan250061 China Key National Demonstration Center for Experimental Mechanical Engineering Education Jinan250061 China Guangxi Key Laboratory of Manufacturing System & Advanced Manufacturing Technology Guilin University of Electronic Technology Guilin541004 China Department of Chemical and Materials Engineering University of Alberta EdmontonABT6G 2H5 Canada

The Bauschinger effect typically occurs in ductile materials and influences their tribological behaviors. However, this phenomenon is rarely reported in brittle materials. The nano-scale plastic deformation observed in brittle materials implies that the Bauschinger effect may also occur during their nano-tribological processes. In this study, molecular dynamics simulations were employed to evaluate the Bauschinger effect in cubic silicon carbide (3C-SiC) and its effect on nano-grinding of 3C-SiC. The results show that defects generated in 3C-SiC during shear deformation recover upon reversal of the shear direction, and defects near the surface of 3C-SiC workpiece generated during nano-grinding also recover upon reversal of the grinding direction, which validates the hypothesis that the Bauschinger effect may occur in 3C-SiC and could benefit its machinability. The Bauschinger effect during bi-directional grinding could help significantly reduce the damage and roughness to the surface of 3C-SiC and also help lower the machining resistance. Such benefits from the Bauschinger effect are found to be more pronounced at relatively lower temperatures, which makes the machinability of 3C-SiC during the bi-directional grinding at relatively lower temperatures comparable to that during the unidirectional grinding at higher temperatures. Therefore, taking advantage of the Bauschinger effect could help lower the operation temperature for high-quality and high-efficiency grinding of 3C-SiC with reduced defects, roughness, and resistance. This study provides an insight into the nano-tribological behaviors of brittle materials and demonstrates an effective approach for their ultra-precision machining. © 2025 Elsevier B.V.

关键词： Machinability

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Adsorption behaviors of DNA nucleobases molecules on 2D Ti2N based materials: A DFT study

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Applied Surface Science 2025年 705卷

作者： Qarnain, Zul Qian, Zhao Shi, Feilong Wang, Chen Bi, Jianqiang Ahuja, Rajeev State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Jinan China Affiliated Hospital of Shandong Academy of Traditional Chinese Medicine Jinan China Condensed Matter Theory Materials Theory Division Department of Physics and Astronomy Uppsala University Uppsala Sweden

In this work, the adsorption behaviors of DNA nucleobases molecules on pristine, defective Ti2N and oxygen-functionalized Ti2NO2 have been investigated using the Density Functional Theory (DFT) within the framework of Van der Waals corrections. It is found that the pristine Ti2N has intense adsorption energy, which is decreased by approaches such as introducing Ti/N defects or attaching the oxygen functional group. Through studies of the equilibrium geometrical configurations, partial density of states, band structure, Bader charge analysis, charge density difference and work function, it is indicated that the adsorption strength of pristine Ti2N towards DNA nucleobases is stronger than defective Ti2N and Ti2NO2. While, in terms of decreasing the recovery time, Ti2NO2 is the best candidate among them for the sensing of DNA nucleobases. This theoretical work is proposed to provide guidance for experimentalists to develop better 2-D sensing materials to detect DNA nucleobases molecules for bio-medical applications in the future. © 2025 Elsevier B.V.

关键词： Van der Waals forces

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Superior mechanical properties for an additively manufactured crack-free Ni-based superalloy with an inherited metastable microstructure after heat treatment

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Journal of Materials Research and technology 2025年 36卷 8108-8121页

作者： Dongyu Wei Lu Shi Wenzhe Zhou Yusheng Tian Beiya Wang Rui Wang Jian He Decheng Kong Guoliang Zhu Baode Sun Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming and State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai 200240 China Shanghai Aerospace System Engineering Institute Shanghai 201108 China China Aerosp Sci & Technology Corp Beijing Inst Space Long March Vehicle Beijing 100076 China

Localized non-equilibrium and rapid solidification usually generate a distinctive metastable microstructure in metals and alloys produced through the laser powder bed fusion. Therefore, it is crucial to modulate the printed microstructure for the final mechanical properties. Several heat treatment procedures were developed to control the cellular structure and carbides of the LPBF (Laser powder bed fusion) ZGH4142 alloy in this work. The relationship between heat treatment, microstructure, and mechanical properties was thoroughly investigated. It shows that traditional standard heat treatment is not the optimal approach for ZGH4142 alloy, and the specimens exhibit moderate high-temperature strength but reduced ductility after high-temperature heat treatment, owing to the presence of oversized carbides. However, directly aged ZGH4142 alloy (900 °C) demonstrates a superior combination of high-temperature ultimate tensile strength (139.7 MPa) and elongation (11.5 %) at 1100 °C. The preserved metastable cellular microstructures hinder dislocation transfer between adjacent cells and limit dislocation slipping within cells for the directly aged counterparts, and the fine carbides strengthen the grain boundary and prevent premature instability therein. The research findings provide valuable insights for exploring heat treatment processes to maintain the inherited metastable microstructure formed during the printing process for other AM Ni-based superalloys.

关键词： Inherited metastable microstructure Mechanical behavior Laser powder bed fusion Ni-based superalloy

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Structural, electrical, phonon, and optical properties of 2D metals: A DFT calculation

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Journal of Applied Physics 2025年第16期137卷

作者： Li, Dongbo Wu, Long Huang, Kaifeng Yu, Liang Wang, Haini Yu, Yaqi Da, Liangguo Tang, Yunqing School of Mechanical and Electrical Engineering Huainan Normal University Huainan232038 China Human-Computer Collaborative Robot Joint Laboratory of Anhui Province Huainan232038 China State Key Laboratory of Advanced Equipment and Technology for Metal Forming Shandong University Jinan250061 China Key Laboratory of High Efficiency and Clean Mechanical Manufacture Ministry of Education School of Mechanical Engineering Shandong University Jinan250061 China

We investigated the structure, electrical, phonon, and optical properties of 2D metals (goldene, silverene, and copperene) by density functional theory. The results of the electronic band structure reveal that goldene and copperene exhibit metallic characteristics, whereas silverene demonstrates semimetallic properties. The results of the electronic density of states show that the s-d-orbital coupling is the strongest in goldene, followed by silverene, and the weakest in copperene. The s-d-orbital coupling has the effect of softening phonons and reducing lattice thermal conductivity. Phonon property analysis demonstrates that there are no imaginary frequencies in the phonon dispersion curves of goldene, silverene, and copperene, indicating their dynamic stability. The results of optical properties show that goldene and copperene exhibit high absorptivity, reflectivity, conductivity, and refractive index in the low-frequency region, and the optical properties of the three 2D metals gradually converge to the same as the frequency increases. This research provides a theoretical foundation and guidance for exploring novel two-dimensional metal materials. © 2025 Author(s).

关键词： Density (optical)

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Achieving ultrafine martensite-bainite duplex microstructures by combining prior cold deformation with chronological control of phase transformation in GCr15 bearing steel

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Journal of Materials Research and technology 2025年 36卷 10267-10280页

作者： Xiaohui Lu Guanglin Yuan Xuanhong Yan Rushan Lu Huajie Shi Yinsong Chen Dongsheng Qian Lin Hua School of Automotive Engineering Wuhan University of Technology Wuhan Hubei 430070 China Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of Technology Wuhan Hubei 430070 China Hubei Engineering Research Center for Green Precision Material Forming Wuhan University of Technology Wuhan Hubei 430070 China School of Materials Science and Engineering Wuhan University of Technology Wuhan Hubei 430070 China

In this work, a strategy is proposed by combining prior cold deformation with chronological control of phase transformation to achieve ultrafine martensite-bainite duplex microstructures in GCr15 bearing steel, which is the specimens with 0∼45 % prior cold deformation are subjected to first martensite transformation at below martensite start (Ms) temperature to form different fraction of first transformed martensite due to the decreasing of Ms temperature caused by prior cold deformation and subsequent transfer to isothermal holding at above Ms temperature for bainite transformation. It is found that prior cold deformation can further accelerates bainite transformation by shortening incubation and growth period, and increasing bainite transformation rate. The specimen with 30 % prior cold deformation after heat-treated by austenitizing at 850 o C for 30min, first martensite transformation at 200 o C for 5min and subsequent bainite transformation at 240 o C for 30min, a marginal improvement of strength and significant improvement of impact toughness are achieved, which is increased by 2.8 % and 20.9 % compared to the specimen with 0 prior cold deformation. Meanwhile, ultrafine bainite platelets of ∼220 nm are achieved, which is refined by 35 % compared to the specimen with 0 prior cold deformation. In addition, the effect of prior cold deformation on the evolution of martensite-bainite duplex microstructures is also discussed.

关键词： Prior cold deformation Martensite-bainite Bainite transformation kinetics Strength-toughness

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Correction to: Constitutive Model and Hot Workability of 022Cr19Ni10 Nuclear-Grade Austenitic Stainless Steel (Journal of Materials Engineering and Performance, (2025), 10.1007/s11665-025-10934-y)

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Journal of Materials Engineering and Performance 2025年 1-1页

作者： Jiang, Changchun Pan, Xujie Ma, Mingjuan Wang, Liqiang Qian, Jing School of Mechanical Engineering Jiangnan University Jiangsu214122 China Wuxi Flange Forging Co. Ltd Jiangsu214156 China Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology School of Mechanical Engineering Jiangnan University Jiangsu214122 China

The name of corresponding author Jing Qian was misspelled in the article as originally published. The original article has been corrected © ASM International 2025.

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Enhanced wear resistance of a die steel via modification of the M7C3 and M23C6 carbides

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Wear 2025年 576-577卷

作者： Shen, Xinyu Peng, Mulan Fu, Hao Wei, Tongtao Wu, Hong Huang, Xiedong Li, Zulai Li, Lu Baker, Ian Shan, Quan Faculty of Material Science and Engineering Kunming University of Science and Technology Kunming650093 China State Key Laboratory of Powder Metallurgy Central South University Changsha410083 China Thayer School of Engineering Dartmouth College HanoverNH03755-8000 United States National & Local Joint Engineering Laboratory for Technology of Advanced Metallic Solidification Forming and Equipment Kunming650093 China

Large volume fractions of carbides in die steels are a crucial source of high wear resistance. However, the inherent brittleness of micrometer sized carbides reduces the toughness, and can cause embrittlement and even premature failure of die steels. In this work, Cr8Mo2VSi die steel, a typical cold work die steel, has been modified by both reducing the volume fraction and refining the M7C3 carbides. The modified Cr8Mo2VSi die steel was produced via a 0.8 wt% reduction of Cr and a 5 % increase in deformation during composition design and rolling process, respectively. Increased aging-induced precipitation of M23C6 carbides in Cr8Mo2VSi can balance the negative effects of the M7C3 carbides, thereby toughening the die steel and extending its fatigue life. Moreover, M7C3 carbides are prone to peeling during wear because of their inherent brittleness, the stacking faults present, and the low interfacial adhesion. The modified Cr8Mo2VSi die steel exhibited superior toughness and fatigue performance and high wear resistance not only due to the increased participation of M23C6 carbides, but also because of the increased number of high-angle grain boundaries resulting from increased deformation. This study aims to provide guidance for the toughening of die steels with high-carbide contents. © 2025 Elsevier B.V.

关键词： Stacking faults

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General Analytical Shakedown Solution for Structures with Kinematic Hardening Materials

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Chinese Journal of Mechanical Engineering 2016年第5期29卷 944-953页

作者： GUO Baofeng ZOU Zongyuan JIN Miao Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University

The effect of kinematic hardening behavior on the shakedown behaviors of structure has been investigated by performing shakedown analysis for some specific problems. The results obtained only show that the shakedown limit loads of structures with kinematic hardening model are larger than or equal to those with perfectly plastic model of the same initial yield stress. To further investigate the rules governing the different shakedown behaviors of kinematic hardening structures, the extended shakedown theorem for limited kinematic hardening is applied, the shakedown condition is then proposed, and a general analytical solution for the structural shakedown limit load is thus derived. The analytical shakedown limit loads for fully reversed cyclic loading and non-fully reversed cyclic loading are then given based on the general solution. The resulting analytical solution is applied to some specific problems： a hollow specimen subjected to tension and torsion, a flanged pipe subjected to pressure and axial force and a square plate with small central hole subjected to biaxial tension. The results obtained are compared with those in literatures, they are consistent with each other. Based on the resulting general analytical solution, rules governing the general effects of kinematic hardening behavior on the shakedown behavior of structure are clearly.

关键词： elastic-plastic elastic shakedown kinematic hardening shakedown limit load general analytical solution

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