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Microstructure and mechanical properties of Ni3Al intermetallics prepared by directional solidification electromagnetic cold crucible technique

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China Foundry 2017年第3期14卷 169-175页

作者： Hong-sheng Ding guo-tian Wang Rui-run Chen jing-jie guo Heng-zhi FuNational Key Laboratory for Precision Hot Processing of Metals School of Materials Science and Engineering Harbin Institute of Technology

The present work focused on the Ni_3Al-based alloy with a high melting point. The aim of the research is to study the effect of withdrawal rate on the microstructures and mechanical properties of directionally solidified Ni-25 Al alloy. Ni_3 Al intermetallics were prepared at different withdrawal rates by directional solidification(DS) in an electromagnetic cold crucible directional solidification furnace. The DS samples contain Ni_3 Al and Ni Al phases. The primary dendritic spacing(λ) decreases with the increasing of withdrawal rate(V), and the volume fraction of Ni Al phase increases as the withdrawal rate increases. Results of tensile tests show that ductility of DS samples is enhanced with a decrease in the withdrawal rate.

关键词： intermetallic directional solidification microstructure mechanical property fracture

Effect of competitive crystal growth on microstructural characteristics of directionally solidified nickel-based single crystal superalloy

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China Foundry 2022年第2期19卷 109-116页

作者： Mang Xu Xiao-qi Geng Xiang-long Zhang guo-huai Liu Ye Wang Zhao-dong Wang jing-jie guo State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China School of Materials Science and Engineering Harbin University of Science and TechnologyHarbin 150040China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

Directionally solidified single crystal superalloy test bars were prepared by the spiral grain selection *** microstructural evolution and orientation characteristics of the starter block and spiral part were studied,and the influence of the competitive growth of crystals on the microstructural characteristics was *** results show that the divergent grain groups,with small size and randomly oriented grains,appear at the bottom of the start block due to the chilling effect,which is an important area for competitive *** the height of the starter block increases,the primary dendrite spacing increases,and the grain density decreases;furthermore,the proportion of grains with an orientation deflection angle less than 10°gradually ***texture gradually becomes stronger as the height of the starter block increases,which indicates that the competitive growth of crystals gradually *** the initial stage of the crystal selection in the spiral part,the obstacle of adjacent grains and spiral passage is the main working *** grains located at the inner side of the front edge of the spiral passage have the growth *** single crystal screening process is achieved at about two-thirds of the spiral height,and the single crystal with the orientation deviation angle of 6.7°from the casting axis is prepared.

关键词： directional solidification Ni-based superalloy microstructural evolution spiral grain selector single crystal

3D Morphology and Formation Process of the Icosahedral Quasicrystalline Phase in Rapidly Solidified Al-Mn Alloy

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Acta Metallurgica Sinica(English Letters) 2016年第1期29卷 28-31页

作者： Hui-Jun Kang Zhong-Lue Hu Xiao-Xia Gao Zong-Ning Chen Yi-Ping Lu Jin-Chuan jie jing-jie guo Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of Technology Department of Mechanical Engineering Texas Tech University School of Materials Science and Engineering Harbin Institute of Technology

Three-dimensional morphology and formation process of icosahedral quasicrystal phase have been investigated in a melt-spun AI-18Mn alloy （in wt%）. Three distinct layers corresponding to varying temperature gradient have been observed on the cross section of the ribbons. 3D morphologies of cellular and dendritic icosahedral phase have been obtained through electro-etching. A model has been proposed to describe the formation process of the icosahedral phase and a-A1 during the rapid solidification. The icosahedral phases are primarily precipitated from the melt into fine cellular and dendritic particles, and subsequently engulfed by the a-A1 which propagates in a planar morphology.

关键词： Rapid solidification Microstructure Icosahedral quasicrystal Aluminum-manganese alloy

Microstructure and mechanical properties of Ti44Al6Nb alloys with different cerium contents

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Rare Metals 2020年第4期39卷 402-407页

作者： Hong-Ze Fang Rui-Run Chen Xiao-Yu Chen Zhi-Kun Ma Hong-Sheng Ding jing-jie guo School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Department of Tank Repair People's Liberation Army Armored Force Engineering InstituteChangchun 130117China

Ti44A16 Nb-based alloy ingots with different cerium(Ce)contents(0,0.05,0.10,0.15,0.20;at%)were prepared by non-consumable vacuum arc smelting furnace(WK-Ⅱ).The surface quality,macrostructure,microstructure,compressive properties and fracture morphology of these ingots were *** results show that Ce has few influences on the surface *** can refine grain size and the average grain size decreases from 0.50 to 0.19 mm with the increase of Ce ***,the microstructure morphology of these ingots changes from large lamellar microstructure to dual-phase *** addition of Ce,CeO and AlCe3 are formed during melting and solidifying,which act as the core of heterogeneous nucleation and refine the *** compressive testing results show that Ce can improve strength and *** ultimate compressive strength increases from 1156.2 to 1472.2 MPa with Ce content increasing from 0 at%to 0.20 at%.The compression ratio is improved from 10.2%to 15.3%with Ce content increasing from 0 at%to 0.10 at%.The refined crystalline strengthening and grain boundary strengthening are the main reasons for the improvement of compressive property.

关键词： Ce TiAl alloy Compressive property Grain refining

High-temperature deformation resistance and creep resistance of a TiAl-based alloy fabricated by cold crucible directional solidification technology

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China Foundry 2020年第5期17卷 378-383页

作者： Shu-lin Dong Xin Ding Rui-run Chen jing-jie guo Heng-zhi Fu Key Laboratory of Electromagnetic Processing of Materials(Ministry of Education) Northeastern UniversityShenyang 110819China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China

In order to improve the high-temperature deformation resistance and creep resistance of TiAl-based alloys,cold crucible directional solidification(CCDS)technology was employed.Aβ-type TiAl-based alloy with the nominal composition of Ti44Al6Nb1Cr2V was prepared using the optimized CCDS parameters of 45 kW input power and 0.5 mm·min^-1 solidification ***-compression testing was utilized to evaluate the hightemperature deformation resistance and creep resistance of the CCDS Ti44Al6Nb1Cr2V *** show that the CCDS Ti44Al6Nb1Cr2V alloy billets contain aligned columnar grains and a high percentage of small-angle ***-compression testing results in the radial direction of the CCDS alloy show a much higher peak stress than other reported results in similar *** much higher hardening exponent and deformation activation energy are obtained,corresponding to the excellent high-temperature deformation resistance and creep resistance,which are because of the hard-oriented grains,weaker stress-strain coordination capability of lamella structure and relatively more hysteretic dynamic ***-compression testing results in the longitudinal direction of the CCDS Ti44Al6Nb1Cr2V alloy show the much higher peak stress than that in the radial direction,indicating the better high-temperature deformation resistance and creep resistance attributed to the hard-oriented lamellae in this condition.

关键词： cold crucible directional solidification TiAl thermo-compression constitutive equations microstructure

Modification of BCC phase and the enhanced reversible hydrogen storage properties of Ti-V-Fe-Mn alloys with varied V/Fe ratios

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China Foundry 2024年第5期21卷 546-554页

作者： Xiang-feng Ma Xin Ding En-lai Liu Rui-run Chen Xin-xiu Wang Yong Zhang jing-jie guo National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China School of Materials Science and Engineering Shandong University of Science and TechnologyQingdao 266500ShandongChina AECC Harbin Dongan Engine Co.Ltd.Harbin 150001China

Ti-V-based alloys are proved of huge potential in storing hydrogen,but the incomplete reversible hydrogen storage capacity caused by overstability of V hydride has limited the large-scale *** this study,Ti_(32)V_(40+x)Fe_(23-x)Mn_(5)(x=0,4,8,12,at.%)alloys were designed,and the effects of V/Fe ratio on phase constitution and hydrogen storage properties were *** main phase of the alloys is body-centered cubic(BCC)phase,and the lattice constants of the BCC phase decrease with the decrease of V/Fe ***,C14 Laves phase exists in alloys with a Fe content of 19at.%to 23at.%.For hydrogenation,the C14 Laves phase can accelerate the hydrogen absorption rate,but the hydrogen absorption capacity is *** the decrease of V/Fe ratio,the hydride gradually *** to its large lattice constant and high hydrogen absorption phase content,the Ti_(32)V_(52)Fe_(11)Mn_(5)alloy shows the most enhanced hydrogen storage properties with hydrogenation and dehydrogenation capacities of 3.588wt.%at 298 K and 1.688wt.%at 343 K,*** hydrogen absorption capacity of this alloy can be reserved to 3.574wt.%after 20 cycles of hydrogen absorption and desorption.

关键词： hydrogen storage Ti-based alloy lattice constant BCC phase

Introduction of rare-earth element Sc in alloy design to modify wear features of dual-phase high-entropy alloy

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Rare Metals 2024年第2期43卷 817-828页

作者： Hao Ren Rui-Run Chen Xue-Feng Gao Tong Liu Gang Qin Yu-Lung Chiu Shi-Ping Wu jing-jie guo guo National Key Laboratory for Precision Hot Processing of Metals School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin150001China School of Metallurgy and Materials University of BirminghamBirminghamB152TTUK

Tailoring the alloy composition,which induces the hard secondary phase to increase hardness and strength to improve the wear features,is a feasible approach for developing wear-resistant metal ***,a group of(AlCoCrFeNi)_(100–x)Sc_(x)(x=0–2.0,at%)high-entropy alloys(HEAs)are designed and the phase compositions and wear behaviors are ***-doped HEA series contain the primary body-centered cubic(BCC)and eutectic phases,in which the eutectic phase is composed of the alternately grown BCC and Laves *** addition promotes the diffusion of Ni atoms from BCC phase to form the Sc-rich Laves phase at the grain *** hardness increases due to solid solution strengthening and second phase *** the second phase strengthening plays a more significant role relative to solid solution *** phase and the oxides caused by wear heating prevent the direct contact between friction pair and HEAs,thus inducing a decreased wear rate from 6.82×10^(−5) to 3.47×10^(−5)m^(3)·N^(−1)·m^(−1).Moreover,the wear mechanism changes from adhesive wear,abrasive wear and oxidative wear to abrasive wear and oxidative wear.

关键词： High entropy alloy(HEA) Laves phase Hardness Wear mechanism

A Hf-doped dual-phase high-entropy alloy: phase evolution and wear features

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Rare Metals 2024年第1期43卷 324-333页

作者： Hao Ren Rui-Run Chen Xue-Feng Gao Tong Liu Gang Qin Yu-Lung Chiu Shi-Ping Wu jing-jie guo National Key Laboratory for Precision Hot Processing of Metals School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China School of Metallurgy and Materials University of BirminghamEdgbastonBirmingham B152TTUK

Initially defined high entropy alloys(HEAs)usually exhibit a single-phase solid-solution ***,two and/or more types of phases in HE As possibly induce the desired microstructure features,which contribute to improving the wear properties of HE ***,we prepare a series of(AlCoCrFeNi)_(100-x)Hf_(x)(x=0,2,4and 6;at%) HEAs and concern their phase compositions,micro structures and wear *** leads to the formation of(Ni,Co)_(2)Hf-type Laves phase and tailors the microstructure from a body-centered cubic(BCC) singlephase structure to a hypoeutectic *** increased hardness from~HV 512.3 to~HV 734.1 is due to solid-solution strengthening,grain refinement strengthening and precipitated phase *** a few oxides(Al_(2)O_(3)+Cr_(2)O_(3)) caused by the wear heating contribute to an 85.5% decrease in wear rate of the HEA system from6.71×10^(-5) to 0.97×10^(-5) m^(3)·N^(-1)·m^(-1).In addition,Hf addition changes the wear mechanism from abrasive wear,mild oxidative wear and adhesive wear to oxidative wear and adhesive wear.

关键词： High entropy alloy Laves phase Hardness Wear mechanism

Microstructure and mechanical properties of Ti44Al6Nb1Cr2V alloy after gaseous hydrogen charging at 1373-1693 K

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Rare Metals 2023年第2期42卷 664-671页

作者： Teng-Fei Ma Rui-Run Chen De-Shuang Zheng jing-jie guo Hong-Sheng Ding Yan-Qing Su Heng-Zhi Fu School of Materials Science and Engineering Harbin Institute of TechnologyHarbin150001China

The hydrogenation behavior of Ti44A16Nb1Cr2V(at%)alloy at temperature range of 1373-1693 K and its effect on microstructure and room-temperature mechanical properties were studied systematically in this *** results show that hydrogen content increases with the increase in temperature,and the maximum hydrogen content is 0.126 wt%at 1693 *** heat of solution of hydrogen is calculated as 82.9 kJ·mol^(-1)by curve fitting,indicating that hydrogen absorptionin TiAl alloys is *** promotes the lamellar colony size because hydrogen promotes the diffusion of *** stabilizes B2phase during hydrogenation resulting in more residual B2phase in the hydrogenated *** nanohardness and elastic modulus decrease after hydrogenation due to that hydrogen weakens the *** Ti44A16Nb1Cr2V alloy exhibits higher plasticity and lower flow stress hydrogenation with 0.039 wt%H,and the ultimate compressive strength decreases from 1220 to 1130 MPa,while the fracture strain is enhanced by 26%.

关键词： TiAl alloys Hydrogenation Hydrogen content Nanohardness Compressive property