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A Study on the microstructure development in Laser-Cladded Tantalum Layers

JOURNAL OF THERMAL SPRAY TECHNOLOGY 2023年第2-3期32卷 751-759页

作者： Yuan, Kang Pang, Xiaoxiao Pi, Ziqiang Lu, Xiaoliang BGRIMM Technol Grp Beijing 100160 Peoples R China BGRIMM Adv Mat Sci & Technol Co Ltd Beijing 102206 Peoples R China Beijing Engn Technol Res Ctr Surface Strengthening Beijing 102206 Peoples R China

In this study, the microstructure development of a laser-cladded tantalum (Ta) layer formed on an iron (Fe) substrate was mainly analyzed. The results showed that typical dendritic crystalline structures were formed in the Ta layer. Fe was detected in the Ta layer, indicating that the upward diffusion of Fe from the substrate occurred. By applying thermodynamic and kinetic calculations, the microstructure development observed in the experiment can be well understood. In the fully molten zones, typical eutectic structure was formed containing BCC-Ta dendrite and MU-TaFe inter-dendrite. While in the partially molten zone away from the laser heating, spherical Ta particle morphology was kept without dendritic structure. To achieve purer Ta layers or coatings by minimizing the effect of the upward diffusion of substrate elements, a high-melting-point tungsten substrate was used in both laser cladding and plasma spraying processes.

关键词： diffusion laser cladding microstructure development tantalum

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Limestone calcined clay cement: mechanical properties, crystallography, and microstructure development

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JOURNAL OF SUSTAINABLE CEMENT-BASED MATERIALS 2023年第4期12卷 427-440页

作者： Sui, Hao Hou, Pengkun Liu, Yanming Sagoe-Crentsil, Kwesi de Souza, Felipe Basquiroto Duan, Wenhui Monash Univ Dept Civil Engn Clayton Vic Australia Univ Jinan Sch Mat Sci & Engn Jinan Peoples R China

Limestone calcined clay cement (LC3) holds promise as a new type of sustainable cement-based material, but the mechanisms underpinning its engineering performance are still poorly understood. Here, a metal intrusion-enhanced imaging approach was employed to quantitatively analyze and link the pore structure development of LC3 to its hydration process, i.e. solid-phase development, and mechanical performance. We found that the early age microstructural development in LC3 is inhomogeneous, with the perimeter of limestone particles displaying higher porosity relative to that surrounding calcined clay and clinker. At later ages, the formation of carboaluminates and calcium-aluminate-silicate-hydrates homogenized the overall microstructure of LC3, thereby delivering improved mechanical performance. Overall, our analysis suggested a more efficient particle packing in LC3 mixes, which decreases the volume/connectivity of micro-pores and can account for LC3's notable flexural strength. These findings can assist the development of improved LC3 binder formulations alongside other ternary binders with possibly higher limestone additions.

关键词： Limestone calcined clay cement (LC3) microstructure development metal intrusion quantitative SEM analysis pore structure flexural strength

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microstructure development, tribological property and underlying mechanism of laser additive manufactured submicro-TiB2 reinforced Al-based composites

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JOURNAL OF ALLOYS AND COMPOUNDS 2020年第0期819卷 152980-000页

作者： Xi, Lixia Guo, Shuang Gu, Dongdong Guo, Meng Lin, Kaijie Nanjing Univ Aeronaut & Astronaut Coll Mat Sci & Technol Yudao St 29 Nanjing 210016 Peoples R China Nanjing Univ Aeronaut & Astronaut Jiangsu Prov Engn Lab Laser Addit Mfg High Perfor Yudao St 29 Nanjing 210016 Peoples R China

Al-based composites reinforced with submicro-TiB2 particles were manufactured by selective laser melting (SLM) of powder mixture under different laser powers. The microstructure evolution and tribological property of SLM-processed AlSi10Mg/TiB2 composites were investigated. Al-based composites with high manufacturing quality and uniform dispersion of TiB2 particles throughout the matrix were obtained. The EBSD results showed that incorporation of TiB2 reinforcements imposed no appreciable influence on the crystallographic orientation and average grain size, while the grain size distribution was distinctly narrowed as a result of limitation on grain growth by addition of ceramic particles. The SLM-processed composites exhibited a continuous tendency of increasing microhardness and decreasing coefficient of friction (COF) along with wear rate with a laser power increasing from 350 to 450 W. The composites showed high microhardness of 126 HV0.2, exceeding those of the Al-Si alloys and composites processing by conventional techniques. A low COF of 0.65 and wear rate of 5.2 x 10(-4) mm(3)N(-1)m(-1) were obtained for bulk-form composites at 450W due to the combined effects of high manufacturing quality, microstructure homogeneity, and sound interfacial bonding. (C) 2019 Elsevier B.V. All rights reserved.

关键词： Al-based composite Selective laser melting (SLM) microstructure development Tribological property

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Heterogeneous microstructure development in additive friction-stir deposited Al-Mg-Si alloy

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ADDITIVE MANUFACTURING 2024年 81卷

作者： Metz, Peter C. Franz, Cole Kincaid, Joshua Schmitz, Tony Lass, Eric A. Babu, Sudarsanam S. Page, Katharine Univ Tennessee Dept Mat Sci & Engn Knoxville TN 37996 USA Univ Tennessee Dept Mech Aerosp & Biomed Engn Knoxville TN 37996 USA Oak Ridge Natl Lab Mfg Sci Div Knoxville TN 37932 USA Oak Ridge Natl Lab Neutron Scattering Div Oak Ridge TN 37831 USA

Aluminum alloy 6061-T6511 was printed by additive friction stir deposition onto a cast aluminum A206-T4 plate. Metallography, X-ray powder diffraction, X-ray pole figure analysis, and electron backscatter diffraction of the center, advancing side, and retreating side of the 6061 deposit reveals different texture and grain structure characteristics across the transverse direction and through each layer. These distinct microstructural domains are indicative of spatially varied temperature, strain rate, and strain accumulation during deposition, and consequently of regions differing in the fraction of dynamic recovery and dynamic recrystallization during deposition. Hardness mapping over the complete cross section at 0.75 mm resolution shows the alloy continues to age after active deposition, and hardness increases over the 5 mm nearest the final printed layer. Additional mapping at 0.10 mm resolution shows intralayer hardness variations of the deposit on the retreating side. These observations demonstrate that complex and non-uniform thermal-mechanical transients occur during additive friction stir deposition, resulting in spatially non-uniform microstructure and properties.

关键词： Additive friction stir deposition Aluminum alloy 6061 X-ray pole figure analysis Electron backscatter diffraction microstructure development

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microstructure development during liquid-phase sintering

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INTERNATIONAL JOURNAL OF MATERIALS RESEARCH 2022年第2期96卷 141-147页

作者： Lee, Sung-Min Kang, Suk-Joong L. Korea Inst Ceram Engn & Technol Seoul South Korea Korea Adv Inst Sci & Technol Dept Mat Sci & Engn Taejon South Korea

microstructure development during liquid-phase sintering has been analysed using the pore-filling theory. The interdependence between sintered density and average grain size, i. e., the relative density - grain size trajectory has been described for various types of processing and sintering parameters. The effects of sintering temperature, initial porosity, average pore size, liquid volume fraction, dihedral and wetting angle, and sintering atmosphere pressure have been evaluated. A critical examination has also been made of the factors determining the trajectory shape and the implication of activation energy for densification. The predicted microstructure developments should demonstrate various possibilities of controlling microstructure during liquid-phase sintering.

关键词： Liquid-phase sintering Pore filling Grain growth Densification microstructure development

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microstructure development in cryogenically rolled oxide dispersion strengthened copper

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MATERIALIA 2020年 9卷

作者： Aghamiri, S. M. S. Zhang, S. H. Ukai, S. Oono, N. Kasada, R. Noto, H. Hishinuma, Y. Muroga, T. Hokkaido Univ Grad Sch Engn Sapporo Hokkaido 0608628 Japan Tohoku Univ Inst Mat Res Sendai Miyagi 9808577 Japan Natl Inst Fus Sci Gifu 5095202 Japan

Recently, advanced oxide dispersion strengthened (ODS) copper alloys have been developed using mechanical alloying process as a fusion material. In this study, to develop a superior ODS copper alloy containing 0.5wt% Y2O3, the effect of cryogenic rolling on microstructure development and tensile properties was studied using high resolution EBSD, TEM and tensile tests. During cryogenic deformation of ODS copper, grain structure remains in submicron size scale as a combinatorial result of geometrically effects, nanotwin bundle deformation, interaction of dislocations with fine oxide particles and some diffusional processes including static recovery and recrystallization. Clear microstructural characterizations confirmed nucleation of fine new oriented recrystallized grains mainly on the HABs of 80%cryogenic rolled ODS copper. Quantitative analyses indicated grain boundary migration at room temperature following cryogenic deformation originated from high driving force induced by grain boundary bulging and high mobility induced by vacancies. The tensile properties of cryogenic deformed samples showed superior tensile strength than room temperature deformation leading to UTS: 624 MPa, elt: 5.5%, while saturation of strength between 60%-80% reduction, approved occurrence of softening by diffusional processes.

关键词： ODS copper Cryogenic rolling microstructure development Recrystallization Tensile properties

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Kinetics-controlled reaction pathway and microstructure development of Ti3SiC2-TiC composite processed through reactive spark plasma sintering

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MATERIALIA 2024年 37卷

作者： Verma, Nisha Bysakh, Sandip Pal, Soupitak Malaviya Natl Inst Technol Jaipur Mat Res Ctr Jaipur 302017 India CSIR Cent Glass & Ceram Res Inst CGCRI Mat Characterizat Div Kolkata 700032 West Bengal India CSIR Cent Glass & Ceram Res Inst CGCRI Adv Ceram & Composites Div Kolkata 700032 West Bengal India

Reactive spark plasma sintering of ternary Ti-Si-C system was performed using three different powder precursors systems 3Ti/Si/2C, 3Ti/SiC/C and 2Ti/TiC/Si, to explore the fundamental physics behind Ti3SiC2 MAX phase formation, its stability and microstructure development, and, finally linked with its hardening and contact induced damage tolerance. Phase evolution in Ti-Si-C system is a complex phenomenon, and, present experimental conditions never yield a phase pure Ti3SiC2 MAX phase, rather results in varying volume fractions of Ti3SiC2-(Ti-x,Si1-x)C solid solution due to non-equilibrium processing conditions exerted by SPS processing which restricts coherent site specific diffusional jumps and promotes the formation of (Ti, Si)C solid-solution instead of well reported non-stoichiometric TiCx. 3Ti/SiC/C precursor was the best candidate for processing composite with highest yields of Ti3SiC2. Phase evolution is guided by the free energy of formation of different phases and chemical affinity amongst the constituent elements rather than the equilibrium phase diagram of the Ti-Si-C system. Presence of free carbon, low temperature liquid phase and slow heating rate are the key requirements for forming phase pure Ti3SiC2, where excess free carbon reduces the stability of Ti3SiC2 via decarburization. Non-equilibrium processing conditions impart nano-precipitation of coherent hexagonal Ti3SiC2 precipitates within a cubic (Ti, Si)C matrix with a distinct orientation relation of (220)(matrix) & boxV;(0004)(precipitate) and <114>(matrix) & boxV;<2-1-10>(precipitate) that has never been reported, instead of growing highest density plane of hcp-on-fcc matrix. Coherency strain and fine interlocking microstructure of the as-processed composite experiences approximate to 36 % of enhancement in hardness followed by an improved contact damage for the as-processed composite.

关键词： Spark plasma sintering Ti3SiC2-TiC composite Transmission electron microscopy X-ray diffraction microstructure development

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Hydration kinetics and microstructure development of Ultra-High Performance Concrete (UHPC) by high volume of phosphorus slag powder

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CEMENT & CONCRETE COMPOSITES 2023年第1期138卷

作者： Huang, Yuepeng Chen, Gaopin Yang, Rui Yu, Rui Xiao, Rengui Wang, Zhiyang Xie, Guiming Cheng, Jinke Guizhou Univ Sch Chem & Chem Engn Guiyang 550025 Peoples R China Wuhan Univ Technol State Key Lab Silicate Mat Architectures Wuhan 430070 Peoples R China Guizhou Univ Collaborat Innovat Ctr Guizhou Prov Efficient Util Guiyang 550025 Guizhou Peoples R China

In this paper, the effect of phosphorus slag(PS)hydration kinetics and microstructural development of UHPC with different degree of substitute (20%, 40% and 60% by mass) were explored. Up to 60% substitution of cement by PS which still shown excellent mechanical property compared to without PS at the age of 60-days. The phase development is a qualitative discussion by thermal gravimetric analysis combined with XRD with Rietveld method, the pore structure is evaluated to MIP. The hydration products are characterized by SEM (scanning electron microscopy) with EDS (Energy-dispersive X-ray) analyses. The results shown that the utilization rate of cement has been significantly improved, for instance, the hydration rate of the cement is enhanced from 54.3% for PS0 to 87.0% for the UHPC with PS60;the Ca/Si ratio decreased with the enhance of PS content and the microstructure is become denser by SEM-EDS tests. The pozzolanic-reaction of PS cloud produce more hydrated products by thermodynamic calculation, which can optimize the pore structure of paste. And the growth trend of C-S-H gel is consistent with the compressive strength growth trend.

关键词： Ultra-High Performance Concrete (UHPC) Hydration kinetics microstructure development Phosphorus slag powder (PS)

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Hydration kinetics and microstructure development of Ultra-High Performance Concrete (UHPC) subjected to microwave pre-curing

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CEMENT & CONCRETE COMPOSITES 2022年第0期129卷

作者： Zhang, Jingjing Yu, Rui Shui, Zhonghe Liu, Kangning Wuhan Univ Technol State Key Lab Silicate Mat Architectures Wuhan 430070 Peoples R China Wuhan Univ Technol Int Sch Mat Sci & Engn Wuhan 430070 Peoples R China Guangxi Univ Guangxi Key Lab Disaster Prevent & Engn Safety Nanning 530004 Peoples R China Wuhan Univ Technol Sch Mat Sci & Engn Wuhan 430070 Peoples R China Wuhan Univ Technol Adv Engn Technol Res Inst Zhongshan City Xiangxing Rd 6 Zhongshan 528400 Guangdong Peoples R China

This research aims to clarify the intrinsic effect of microwave pre-curing on the hydration kinetics and microstructure development of Ultra-High Performance Concrete (UHPC). Six hours after casting, the UHPC samples are subjected to microwave pre-curing for 60-240 s. Then, the macro and micro characteristics of the cured UHPC are evaluated. The observed experimental results show that the microwave treatment can create a dense shell around the cured UHPC's periphery, which can resist the lateral deformation of the specimen and guarantee the excellent mechanical properties of the treated sample. Moreover, when steel fibres are included into UHPC, the reflection and shielding effect of the 3D fibres network can significantly block the promotion effect of microwave on the strength development of UHPFRC. Additionally, due to the high energy of microwave, high polymerization hydration products and advanced pore structure (micro and meso scales) can be observed in the pre-cured UHPC.

关键词： Ultra-high performance concrete (UHPC) Microwave pre-curing Hydration kinetics microstructure development Polymerization

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Quantitative effect of seawater on the hydration kinetics and microstructure development of Ultra High Performance Concrete (UHPC)

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CONSTRUCTION AND BUILDING MATERIALS 2022年 340卷

作者： Sun, Meijuan Yu, Rui Jiang, Chunyuan Fan, Dingqiang Shui, Zhonghe Wuhan Univ Technol State Key Lab Silicate Mat Architectures Wuhan 430070 Peoples R China Wuhan Univ Technol Sch Mat Sci & Engn Wuhan 430070 Peoples R China Wuhan Univ Technol Int Sch Mat Sci & Engn Wuhan 430070 Peoples R China Guangxi Univ Guangxi Key Lab Disaster Prevent & Engn Safety Nanning 530004 Peoples R China Wuhan Univ Technol Adv Engn Technol Res Inst Zhongshan City Xiangxing Rd 6 Zhongshan 528400 Guangdong Peoples R China

This paper aims at quantitatively investigating the effect of seawater on the hydration kinetics and microstructure development of Ultra-High Performance Concrete (UHPC). Specifically, the macroscopic properties of UHPC mixed with seawater are tested, including fresh behaviors, mechanical properties and autogenous shrinkage. In addition, hydration products, hydration heat and hydration degree of UHPC made with seawater are quantitatively evaluated. Finally, the influences of seawater on the surface morphology, nano-mechanical properties and pore structure of UHPC are analyzed. The obtained results uncover that the incorporation of seawater can dramatically decrease the flowability, enhance the flexural and compressive strengths, as well as deteriorate the autogenous shrinkage of UHPC. Moreover, with the addition of seawater, the hydration degree can be increased by 4.67%, not only by consuming more cementitious materials to generate more hydration products (about 12.25%), but also by enhancing the mean chain length of C-S-H gels from 3.5068 to 4.1595 and increasing Q(2)/Q(1) from 0.7533 to 1.0796 to improve the polymerization of hydration products. Additionally, the incorporation of seawater can contribute to a dense microstructure of UHPC by enhancing indentation modulus and hardness of paste by approximately 25.25% and 29.10%, optimizing the ITZ by about 15 mm, as well as refining pore size and reducing the porosity by more than 8%.

关键词： Ultra-High-Performance Concrete (UHPC) Seawater Hydration kinetics microstructure development Mechanism

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