S. Liu, C. Li, X. Jin, D. Ma, Q. Yan, G. Liu, J. Liu, X. Cao, H. Wang
International Journal of Mechanical Sciences 285 (2025) 109822

Abstract. Surface post-processing of metal additive manufacturing components is challenging due to their typically complex geometries (e.g., curved surfaces) coupled with high initial surface roughness. Herein, we propose an efficient solid dielectric electrochemical polishing (SDECP) method employing ion exchange resin particles with a porous structure that absorbs and stores electrolytes as a conductive medium. This method enhances the surface quality of additively manufactured components with Bézier curved surfaces to a mirror finish, achieving improvements in Sa, Sq, and Sz of 91.5%, 91.7%, and 86.9%, respectively. Planetary motion strategies are implemented to optimize mass transfer on the anode surface in the discontinuous solid dielectric. Results indicate that bidirectional planetary motion (BPR) in SDECP effectively improves the uniformity of surface roughness and material removal across different regions of the part. Furthermore, we quantitatively describe the relationship between material removal rate (MRR) and average current in SDECP. The intermittent material removal mechanism of SDECP is elucidated utilizing discrete element method (DEM) simulations. Our work offers innovative insights into the material removal mechanisms of SDECP, presenting an efficient approach for overall surface post-processing of metal additive manufacturing component.

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This work was supported by the National Natural Science Foundation of China [grant numbers 52375402, 52205439], China Space Foundation Aerospace Propulsion Public Welfare Special Fund [grant number KDJJ20230502014], China Scholarship Council (grant number 202306030013), Fundamental Research Funds for the Central Universities of China (NG2024006), and Singapore Ministry of Education Academic Research Funds (A-8001225-00-00).

Z. Zhang, Y.J. Lee, Q. Yan, H. Wang, Z. Tong, X. Jiang
Tribology International 202 (2025) 110341

Abstract. The nanoscratch test, as an established technique for assessing material tribological properties has received significant attention. However, the symmetry and anisotropy in scratching performances as well as the quantitative correlation between the orientation-dependent deformation and inherent microscopic deformation mechanism remain unexplored. Herein, crystal plasticity simulations can quantitatively capture scratching forces, elastic recovery, and surface pile-ups, as well as accurately describe inner deformation fields and lattice rotation patterns, as confirmed by experimental results. The simulation results reveal that surface pile-up and elastic recovery mappings on (001)-, (011)-, and (111)-oriented samples exhibit eight-fold, four-fold, and six-fold symmetries, respectively. The orientation-dependent location and intension of both slip activities and lattice rotation, determine the features of macroscopic elastoplastic deformation under scratching.

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Supported by Ministry of Education, Singapore, Academic Research Funds (Grant Nos.: A-8001225–00-00 and MOET2EP50220–0010).

Q. Yan, B. Chen, Z. Jia, J. Yang, J. Wan, S. Li, L. Jia, J. Shen, J. Li, W.F. Lu, H. Wang
Additive Manufacturing 92 (2024) 104364

Abstract. A dual-networked distribution of the reinforcements holds promise for achieving a balance between high-strength and moderate plasticity in titanium matrix composites (TMCs). Unfortunately, achieving this improvement in TMCs via additive manufacturing (AM) methods, presents significant challenges. Those challenges arise from the inherent differences in chemical and physical properties, which often led to agglomeration of the reinforcement and cracks caused by the high thermal residual stresses. To overcome those issues, this study focuses on the development of Ti-6Al-4V (Ti64) alloys incorporated with 0.5 wt% graphene nanosheets (GNSs) constructing a dual quasi-continued TiC network structure via powder bed fusion. The results exhibited a super-high tensile yield strength (1307 MPa), accompanied by a moderated elongation of 2.6% with reduced residual stress. The microstructure, phase contents, and mechanical performance were thoroughly investigated. A thermo-metallurgical-mechanical coupling model was developed, considering factors such as laser absorption effects and laser scanning strategy. Finally, a reasonable dual-network model was built to elucidate the contribution of various strengthening factors. Overall, this study illustrates that the strength of GNS/Ti64 composites is affected by the factors of GNS distribution, quasi-continue network in-situ TiC particles, temperature and residual stress field, offering a reference for fabricating high-strength nanocarbon/Ti64 composites by AM methods.

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Supported by National Natural Science Foundation of China (52274367), the Research Fund of the State Key Laboratory of Solidification Processing (NPU), China (2022-QZ-02), the Key Research and Development Plan of Shaanxi Province (2021KW-23; 2020KW-034), Singapore A*STAR Grant (No. A19E1a0097), Singapore Ministry of Education Academic Research Funds (Grant Nos. : MOE-T2EP50120-0010, MOE-T2EP50220-0010, and A-8001225-00-00), Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University (CX2021058), and China Scholarship Council (CSC NO. 202106290077).