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Analysis of interaction between dislocation and interface of aluminum matrix/second phase from electronic behavior

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Journal of Materials Science & Technology 2023年第5期136卷 78-90页

作者： Qianxing Yin Guoqing Chen Xi Shu Binggang Zhang Chun Li Zhibo Dong Jian Cao Rong An Yongxian Huang State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

The inhibitory effect of the second phase on dislocation movement has long been deemed as a great con-tribution to the strengthening of alloys.We investigate the electronic behavior at theα-Al matrix/second phase interface to explore its inhibitory effect on dislocation movement.This work focuses on the dif-ficulty in dislocation movement on the interface ofα-Al/Al_(3)Sc,α-Al/θ’(Al_(2)Cu),andα-Al/T_(1)(Al_(2)CuLi)of aluminum-lithium-scandium alloy based on detailed transmission electron microscopy investigation and electron transport calculation.The more drastic the electron transport between two atoms at the inter-face,the more intense the interaction between them,corresponding to the larger difficulty in breaking and forming bonds between them during the movement process of the extra half plane of dislocation on the interface.The calculated difference in density of valence electrons and differential charge density atα-Al/second phase interface reveals that Al_(3)Sc is characterized by the largest resistance to dislocation movement compared toθ’(Al_(2)Cu)and T_(1)(Al_(2)CuLi).The large differential charge density between the in-terface of(100)Al_(3)Sc/(100)Al demonstrates the strong bonds betweenα-Al and Al_(3)Sc and the large difficulty for the extra half plane of dislocation to form or break bonds during the movement process atα-Al/Al_(3)Sc interface.The dislocation pile-up indicates a discernible hindering effect of theα-Al/Al_(3)Sc interface on dislocation movement.The hindering effect presented byα-Al/Al_(3)Sc interface is favorable for the tensile strength.

关键词： Dislocations Microstructural interface Aluminum alloy Electron transport First-principles calculation

Additively Manufactured Flexible Electronics with Ultrabroad Range and High Sensitivity for Multiple Physiological Signals'Detection

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Research 2022年第4期2022卷 707-717页

作者： Huanhuan Feng Yaming Liu Liang Feng Limeng Zhan Shuaishuai Meng Hongjun Ji Jiaheng Zhang Mingyu Li Peng He Weiwei Zhao Jun Wei Sauvage laboratory for Smart Materials Shenzhen Key Laboratory of Flexible Printed Electronics TechnologyHarbin Institute of Technology(Shenzhen)China State Key Laboratory of Advanced Welding and Joining(Shenzhen) Harbin Institute of Technology(Shenzhen)China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyChina

Flexible electronics can be seamlessly attached to human skin and used for various purposes, such as pulse monitoring, pressure measurement, tensile sensing, and motion detection. Despite their broad applications, most flexible electronics do not possess both high sensitivity and wide detection range simultaneously;their sensitivity drops rapidly when they are subjected to even just medium pressure. In this study, ultrabroad-range, high-sensitivity flexible electronics are fabricated through additive manufacturing to address this issue. The key to possess high sensitivity and a wide detection range simultaneously is to fabricate flexible electronics with large depth-width ratio circuit channels using the additive manufacturing inner-rinsing template method. These electronics exhibit an unprecedented high sensitivity of 320 kPa^(−1) over the whole detection range, which ranges from 0.3 to 30,000 Pa (five orders of magnitude). Their minimum detectable weight is 0.02 g (the weight of a fly), which is comparable with human skin. They can stretch to over 500% strain without breaking and show no tensile fatigue after 1000 repetitions of stretching to 100% strain. A highly sensitive and flexible electronic epidermal pulse monitor is fabricated to detect multiple physiological signals, such as pulse signal, breathing rhythm, and real-time beat-to-beat cuffless blood pressure. All of these signals can be obtained simultaneously for detailed health detection and monitoring. The fabrication method does not involve complex expensive equipment or complicated operational processes, so it is especially suitable for the fabrication of large-area, complex flexible electronics. We believe this approach will pave the way for the application of flexible electronics in biomedical detection and health monitoring.

关键词： fatigue additive stretching

One-step PDA coating strategy on pure Zn for blood-contacting engineering

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Journal of Materials Science & Technology 2022年第28期123卷 78-91页

作者： Xiaoyun Qi Shicheng Zhou Hui Fang Shuhan Yang Chunjin Hang Yanhong Tian Chenxi Wang State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

The mechanical performance degradation caused by pitting corrosion and the insufficient biocompatibility induced with ion release inhibit the application of Zn as the new biodegradable metallic materials for blood-contacting intervention therapy.This work successfully coats a uniform polydopamine(PDA)layer on pure Zn via a one-step deposition process without introducing heavy metal elements or detrimental additives.Enhanced corrosion resistance and uniform corrosion have been performed on PDA coated Zn with corrosion products and pits reduced significantly than pure Zn during in vitro degradation.Thrombosis could be prohibited by anticoagulation performance with prothrombin time and activated partial thromboplastin time prolonged after co-incubation,and an almost 40%decrease of platelets adhesion,indicating the improved blood compatibility of coated Zn.Additionally,the poly(lactic-co-glycolic acid)(PLGA)is filmed on PDA coated Zn to realize a smooth double-coated structure with superior mechanical performance under stress loading to stably serve the multifunctional application,such as drug loading.Our strategy not only represents a facile and biological friendly method for Zn surface modification but also puts forward new ideas on preparing PDA-based coatings on active biodegradable alloys,which are beneficial for better blood-contacting engineering.

关键词： Biodegradable Pure Zn Uniform corrosion Blood compatibility Doubled-coated structure

Releasing the residual stress of C_(f)/SiC-GH3536 joint by designing an Ag-Cu-Ti+Sc_(2)(WO_(4))_(3) composite filler metal

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Journal of Materials Science & Technology 2022年第13期108卷 102-109页

作者： P.Wang X.Liu H.Wang J.Cao J.Qi J.Feng State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

Due to native character of thermal expansion coefficient(CTE)mismatch between C_(f)/SiC and GH3536,achieving high strength joint was a huge challenge for C_(f)/SiC-GH3536 joints.Herein,a composite filler metal of Ag-Cu-Ti+Sc_(2)(WO_(4))_(3) was developed to join C_(f)/SiC and GH3536.This work introduced Sc_(2)(WO_(4))_(3) to Ag-Cu-Ti system as a negative thermal expansion(NTE)reinforcing phase to release joint residual stress.Sc_(2)(WO_(4))_(3) was evenly distributed in the brazing seam and reacted with Ti to form Ti_(3)O_(5) reaction layer.The results of finite element analysis showed that the residual stress of the joints was effectively released by introducing Sc_(2)(WO_(4))_(3) reinforcing phase,and the mises stress was decreased from447 to 401 MPa.The maximum shear strength of the C_(f)/SiC-GH3536 joint brazed with Ag-Cu-Ti+6 vol%Sc_(2)(WO_(4))_(3) filler alloys was 64 MPa,which was about 2.6 times higher than that of Ag-Cu-Ti alloys.The results of this study provide a promising strategy for the introduction of new Sc_(2)(WO_(4))_(3) reinforcing phase in Ag-Cu-Ti system,and improve the reliability and feasibility of composite brazing alloy in brazing filed.

关键词： Negative thermal expansion Brazing Residual stress Composite brazing alloy CTE

Microstructure design of C/C composites through electrochemical corrosion for brazing to Nb

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Journal of Materials Science & Technology 2022年第9期104卷 33-40页

作者： Jin Ba Xu Ji Bin Wang Peixin Li Jinghuang Lin Jian Cao Junlei Qi State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

Surface structure of C/C composites has been regulated through electrochemical corrosion at room temperature to modify the residual stress and improve the joining strength when brazed to Nb.The unique crevice corrosion in C/C composites is investigated to reveal the change of corrosion depth and fiber size.The interlacing zone of carbon fiber reinforced brazing alloy replaces the reaction layer in the original joint.joining area is increased dramatically and the continuous crack will be hindered.The interlacing zone eliminates the stress concentration and relieves the residual stress through reducing the property mismatch.All advantages contribute to the joining quality of C/C–Nb.Shear strength of C/C–Nb joint with 80μm depth reached 37.7 MPa,which was 1.2 times higher than that of original joint.Surface structure design of C/C composites not only expands the application in structure component,but also exhibits the promising application in energy field.

关键词： Thermal corrosion Electrochemical corrosion C/SiC composites Braze

joining SiO_(2)based ceramics:recent progress and perspectives

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Journal of Materials Science & Technology 2022年第13期108卷 110-124页

作者： Haohan Wang Jinghuang Lin Junlei Qi Jian Cao State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

Nowadays,SiO_(2)based material is one of the widest used materials in optical,microelectromechanical system,aerospace and some other industries.In practical application,SiO_(2)based materials are required to be joined with themselves or other heterogeneous materials to assemble products with various functions.And the joining quality directly affects the mechanical performances and functional properties of assembled products.Though many researchers studied different joining technologies,explored the microstructure of joining interface and tested after-joining properties,a review that summarizes the recent cutting-edge researches and development tendency of joining technologies for SiO_(2)based ceramics is still absent.Therefore,according to different applications and requirements,this review summarizes the widely used joining technologies and discusses corresponding joining mechanisms,current research progress and suitable applications.Due to the wide applications in specific industry,laser welding,anodic bonding and wafer bonding are discussed in detail.Further,brazing,the widest used method in SiO_(2)joining,has been elaborated deeply in its wetting mechanism,residual stress control,interfacial microstructure and mechanical performance aspects.In the end,this review proposed the future development trends of SiO_(2)ceramics joining,aiming at offering a full-view of potential improvements in SiO_(2)ceramic joining technologies.

关键词： SiO_(2)joining current research progress brazing future development trend

Surface co-hydrophilization via ammonia inorganic strategy for low-temperature Cu/SiO_(2) hybrid bonding

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Journal of Materials Science & Technology 2023年第18期149卷 161-166页

作者： Qiushi Kang Ge Li Zhengda Li Yanhong Tian Chenxi Wang State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

1.Introduction During massive data movements in digital computing systems,several issues have emerged such as high latency,energy ineffi-ciency,and low bandwidth due to the physical separation of pro-cessor and memory units(so-called memory wall)[1-3].To miti-gate the data-movement limitations,three-dimensional(3D)chip integration becomes an optimal solution within von Neumann ar-chitecture since the dense vertical interconnections shorten the distance between chips[4,5].However,the extensively used micro solder bumps for 3D chip stacking impede the further improve-ment of interconnection pitch(<10μm).In this scenario,the Cu/SiO_(2) hybrid bonding technology came into being.Owing to the coexistence of planarized Cu connections and SiO_(2) layers,Cu/SiO_(2) hybrid bonding is the desirable enabler of submicron ultra-dense integration(<1μm),which benefits from Cu-Cu and SiO_(2)-SiO_(2) homogeneous direct bonding replacing micro bumps and underfill[6,7].

关键词： bonding interconnection integration

Residual stress distribution as a function of depth in graphite/copper brazing joints via X-ray diffraction

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Journal of Materials Science & Technology 2019年第11期35卷 2470-2476页

作者： Chun Li Xiaoqing Si Jian Cao Junlei Qi Zhibo Dong Jicai Feng State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology

The residual stress distributions as a function of depth in three different graphite/copper brazing joints:with no interlayer,with a copper interlayer and with a niobium interlayer are measured via X-ray diffraction by transmission geometry.The residual stress in all the joints is found to be generally compressive and increasing from the surface to the interface.Copper and niobium interlayers are both effective in alleviating the residual stress in the joint and the stress value in the joint with a niobium interlayer appearing to be the lowest.The strength of the joint is demonstrated to be closely related to the residual stress and the fracture position of the joint corresponds well with the highest residual stress.

关键词： Brazing Residual stress XRD Graphite Copper

Joint formation mechanism of high depth-to-width ratio friction stir welding

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Journal of Materials Science & Technology 2019年第7期35卷 1261-1269页

作者： Yongxian Huang Yuming Xie Xiangchen Meng Junchen Li Li Zhou State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology

High depth-to-width ratio friction stir welding is an attractive method for the joining demands of alum inum profiles, which is sparked with its extrem ely low heat input and high mechanical performance. In this study, the joint form ation mechanism was studied by a num erical model of plastic flow combined with experim ental approaches. A fluid-solid-interaction algorithm was proposed to establish the coupling model, and the material to be welded was treated as non-New tonian fluid. The thread structure and the milling facets on tool pin prom oted drastic turbulence of material. The thread structure converged the plasticized material by its inclined plane, and then drove the attached material to refill the welds. The milling facets brought about the periodic dynamic material flow. The thread structure and the milling facets increased the strain rate greatly under the extremely low heat input, which avoided the welding defects. The condition of the peak tem perature of 648 K and the strain rate of 151 s^-1 attributed to the lowest coarsening degree of precipitate. The tensile strength of the joint reached 265 MPa, equivalent to 86% of base material. The amelioration via the material flow model inhibits the welding defects and optimizes the param eter intervals, providing references to extracting process-structure-property linkages for friction stir welding.

关键词： Friction stir welding Joint formation Material flow Al-Mg-Si alloy Microstructure Mechanical properties