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Thickness dependence of viscoelastic stress relaxation of laminated microbeams due to mismatch strain

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Applied Mathematics and Mechanics(English Edition) 2022年第4期43卷 467-478页

作者： Xiaosheng CAI Nenghui ZHANG Hanlin LIU Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China

Time-dependent behaviors due to various mismatch strains are very important to the reliability of micro-/nano-devices.This paper aims at presenting an analytical model to study the viscoelastic stress relaxation of the laminated microbeam caused by mismatch strain.Firstly,Zhang’s two-variable method is used to establish a mechanical model for predicting the quasi-static stress relaxation of the laminated microbeam.Secondly,the related analytical solutions are obtained by combining the differential method and the eigenvalue method in the temporal domain.Finally,the influence of the substrateto-film thickness/modulus ratio on the relaxation responses of the laminated microbeam subject to a step load of the mismatch strain is studied.The results show that the present predictions are consistent with the previous theoretical studies.Furthermore,the thickness dependence of stress relaxation time of the laminated microbeam is jointly determined by the intrinsic structural evolution factors and tension-bending coupling state;the stress relaxation time can be controlled by adjusting the substrate-to-film thickness/modulus ratio.

关键词： laminated structure stress relaxation mismatch strain tension-bending coupling effect analytical method

Fabrication of laminated TiB2-B4C/Cu-Ni composites by electroplating and spark plasma sintering

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Journal of Materials Science & Technology 2017年第10期33卷 1172-1176页

作者： Ziyi Wu Jinyong Zhang Taojie Shi Fan Zhang Liwen Lei Han Xiao Zhengyi Fu State Key Lab of Advanced Technology for Material Synthesis and Processing Wuhan University of Technology Wuhan 430070 China

We proposed a new method, electroplating followed by spark plasma sintering（SPS）, to fabricate laminated TiB2-B4 C/Cu-Ni composites with high strength and high toughness. It is found that a thin intermediate Cu layer can effectively enhance the strength of the interface between the ceramics and the metals, resulting in a high flexural strength and toughness of the laminated TiB2-B4 C composites simultaneously. A flexural strength and fracture toughness of 651 MPa and 11.6 MPam^（1/2） respectively,are achieved, an approximately 90% improvement over TiB2-B4 C bulk.

关键词： laminated structure Electroplating Spark plasma sintering B4C ceramic

A graphene-laminated electrode with high glucose oxidase loading for highly-sensitive glucose detection

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Journal of Materials Science & Technology 2021年第7期66卷 57-63页

作者： Yabin Hao Minghe Fang Chuan Xu Zhe Ying Han Wang Rui Zhang Hui-Ming Cheng You Zeng Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China Liaoning Cancer Hospital and Institute Shenyang 110042China Shenzhen Geim Graphene Center Tsinghua-Berkeley Shenzhen InstituteShenzhen 518055China

Graphene oxide(GO) has received considerable attention for glucose detection because of high surface area, abundant functional groups, and good biocompatibility. Defects and functional groups of the GO are beneficial to immobilization of glucose oxidase(GOD), but sacrificing electron-transfer capability for highly-sensitive detection. In order to obtain high GOD loading and highly-sensitive detection of biosensors, we first designed and fabricated a graphene-laminated electrode by combining GO and edgefunctionalized graphene(FG) layers together onto glassy-carbon electrode. The graphene-laminated electrodes exhibited faster electron transfer rate, higher GOD loading of 3.80 × 10^(-9) mol·cm^(-2), and higher detection sensitivity of 46.71 μA·mM^(-1)·cm^(-2) than other graphene-based biosensors reported in literature. Such high performance is mainly attributed to the abundant functional groups of GO, high electrical conductivity of FG, and strong interactions between components in the graphene-laminated electrodes.By virtue of their high enzyme loading and highly-sensitive detection, the graphene-laminated electrodes show great potential to be widely used as high-performance biosensors in the field of medical diagnosis.

关键词： Graphene laminated structure Electrode Glucose detection Biosensor

Fabrication of(TiB/Ti)-TiAl composites with a controlled laminated architecture and enhanced mechanical properties

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Journal of Materials Science & Technology 2021年第3期62卷 221-233页

作者： Hao Ding Xiping Cui Naonao Gao Yuan Sun Yuanyuan Zhang Lujun Huang Lin Geng School of Materials Science and Engineering Harbin Institute of TechnologyP.O.Box 433Harbin150001China Division of Superalloys Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

The(TiB/Ti)-TiAl composites with a laminated structure composing of alternating TiB/Ti composite layers,α_(2)-Ti_(3)Al interfacial reaction layers of andγ-TiAl layers were successfully pre pared by spark plasma sintering of alternately stacked Tib_(2)/Ti powder layers and TiAl powder layers.And the influence of thickness ratio of Tib_(2)/Ti powder layers to TiAl powder layers on microstructure evolution and mechanical properties of the re sulting(TiB/Ti)-TiAl laminated composites were investigated systemically.The results showed that the thickening ofα_(2)-Ti_(3)Al layers which originated from the reaction of Ti and TiAl was significantly hindered by introducing Tib_(2)particles into starting Ti powders.As the thickness ratio of Tib_(2)/Ti powder layers to TiAl powder layers increased,the bending fracture strength and fracture toughness at room temperature of the final(TiB/Ti)-TiAl laminated composites were remarkably improved,especially for the(TiB/Ti)-TiAl composites prepared by Tib_(2)/Ti powder layers with thickness of 800μm and TiAl powder layers with thickness of 400μm,whose fracture toughness and bending strength were up to 51.2 MPa·m^(1/2)and 1456 MPa,respectively,293%and 108%higher than that of the monolithic TiAl alloys in the present work.This was attributed to the addition of high-performance network TiB/Ti composite layers.Moreover,it was noteworthy that the ultimate tensile strength at 700℃of(TiB/Ti)-TiAl composites fabricated by 400μm thick Tib_(2)/Ti powder layers and 400μm thick TiAl powder layers was as high as that at 550℃of network TiB/Ti composites.This means the service temperature of(TiB/Ti)-TiAl laminated composites was likely raised by 150℃,meanwhile a good combination of high strength and high toughness at ambient tempe rature could be maintained.Finally,the fracture mechanism of(TiB/Ti)-TiAl laminated composites was proposed.

关键词： Titanium aluminide matrix composites laminated structure High temperature properties Strengthening-toughening

Microstructure evolution and improved properties of laminated titanium matrix composites with gradient equiaxed grains

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Science China(Technological Sciences) 2020年第12期63卷 2687-2697页

作者： WANG Shuai HUANG LuJun JIANG Shan ZHANG Rui AN Qi SUN Yuan GENG Lin School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

With the purpose of improving both the strength and ductility,gradient equiaxed grains were successfully achieved in the matrix of the laminated TiB/Ti-TiB/Ti-6.58Al-1.76Zr-1.04V-0.89Mo composite via water quenching(WQ) and thermal compressing deformation. Gradient equiaxed grains varied from approximately 1.0 μm in TiB/Ti-6.58Al-1.76Zr-1.04V-0.89Mo layer to 5.5 μm in TiB/Ti layer. The formation of the gradient structure was related to the alloying elements diffusion during the initial sintering process,and the equiaxed shape was constructed by dynamic recrystallization during thermal compressing. WQ treatment before thermal compressing was adopted to obtain fine lamellar structure,which promoted the segmentation of αlamellae,and accelerated the dynamic recrystallization process. Raising the quenching temperature can increase the proportion of equiaxed grains in the composite,which improved both the bending strength and ductility. Compared with the as-sintered specimen,the specimen with gradient equiaxed grains exhibited nearly 30% enhancement in flexural strength(from 1719 to 2218 MPa),and the ultimate bending fracture strain was increased from 7.0% to 17.2%. This significant improvement should be attributed to the coordination deformation by interface gradient grains,the grain refinement strengthening and the good balance between strength and ductility of the recrystallized equiaxed grains.

关键词： titanium matrix composites laminated structure gradient equiaxed grains microstructure evolution dynamic recrystallization bending properties

Fracture Toughness Properties of Three Different Biomaterials Measured by Nanoindentation

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Journal of Bionic Engineering 2007年第1期4卷 11-17页

作者： Ji-yu Sun Jin Tong Key Laboratory of Terrain-Machine Bionics Engineering （Ministry of Education China） Jilin University （Nanling Campus） Changchun 130022 P. R. China

The fracture toughness of hard biomaterials, such as nacre, bovine hoof wall and beetle cuticle, is associated with fibrous or lamellar structures that deflect or stop growing cracks. Their hardness and reduced modulus were measured by using a nanoindenter in this paper. Micro/nanoscale cracks were generated by nanoindentation using a Berkovich tip. Nanoindentation of nacre and bovine hoof wall resulted in pile-up around the indent. It was found that the fracture toughness （Kc） of bovine hoof wall is the maximum, the second is nacre, and the elytra cuticle of dung beetle is the least one.

关键词： biomimetics bionics biomaterials nanoindentation laminated structure fracture toughness

Fabrication and characterization of laminated Ti-(TiB + La2O3)/Ti composite

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Progress in Natural Science:Materials International 2015年第5期25卷 453-459页

作者： Yuanfei Han Hongqiang Duan Weijie Lu Liqiang Wang Di Zhang State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong University

The incorporation of ceramic particulate reinforcements into titanium alloys can improve the specific strength and specific stiffness,while inevitably reduce the plasticity and ductility.In this study,in situ synthesized multilayer Ti-(TiB +LaO)/Ti composite was designed by learning from the microstructure of nature biological materials with excellent mechanical properties.The Ti-(TiB + LaO)/Ti composite with unique characteristic of laminated structure was prepared by combined powder metallurgy and hot rolling.The method has the synthesize advantages with in-situ reaction of Ti and LaBat high temperature and controllability of reinforcements size and constituent phases in composites.The result shows that the pores in the as sintered laminated structure composite completely disappeared after hot rolling at 1050℃.The agglomerated reinforcement particles were well dispersed and distributed uniformly along the rolling direction.The thickness of pure Ti layer and(TiB+LaO)/Ti composite layer decreased from 1 mm to about 200 μm.Meanwhile,the grains size was refined obviously after rolling deformation.The room temperature tensile test indicates that the elongation of the laminated Ti-(TiB + LaO)/Ti composite improved from 13%to 17%in comparison with the uniform(TiB + LaO)/Ti composite,while the tensile strength had little change.It provides theoretical and experimental basis for fabricating the novel high performance laminated Ti-(TiB + LaO)/Ti composites.

关键词： Titanium matrix composites laminated structure Microstructure Mechanical properties

Thermal and Mechanical Analysis of Composite laminated structures

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Thermal and Mechanical Analysis of Composite Laminated Struc...