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Precise regulation of the phase transformation for pyrolusite during the reduction roasting process

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International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 81-90页

作者： Ruofeng Wang Peng Gao Shuai Yuan Yanjun Li Yingzhi Liu Cheng Huang School of Resources and Civil Engineering Northeastern UniversityShenyang 110819China National-Local Joint Engineering Research Center of High-efficient Exploitation Technology for Refractory Iron Ore Resources Shenyang 110819China

The mechanism involved in the phase transformation process of pyrolusite (MnO_(2)) during roasting in a reducing atmosphere was systematically elucidated in this study,with the aim of effectively using low-grade complex manganese ore *** to single-factor experiment results,the roasted product with a divalent manganese (Mn^(2+)) distribution rate of 95.30% was obtained at a roasting time of 25 min,a roasting temperature of 700℃,a CO concentration of 20at%,and a total gas volume of 500 mL·min^(-1),in which the manganese was mainly in the form of manganosite (MnO).Scanning electron microscopy and Brunauer–Emmett–Teller theory demonstrated the microstructural evolution of the roasted product and the gradual reduction in the pyrolusite ore from the surface to the core Thermodynamic calculations,X-ray photoelectron spectroscopy,and X-ray diffractometry analyses determined that the phase transformation of pyrolusite followed the order of MnO_(2)→Mn_(2)O_(3)→Mn_(3)O_(4)→MnO phase by phase,and the reduction of manganese oxides in each valence state proceeded simultaneously.

关键词： pyrolusite phase transformation reduction roasting microstructural evolution reaction mechanism

Microstructure evolution and phase transformation of the mushy zone in a quenchedβ-solidifying TiAl alloy

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Journal of Materials Science & Technology 2024年第2期169卷 28-41页

作者： Fuqiang Zhang Xianfei Ding Leming Xu Xin Feng Hai Nan Jianping He Yongfeng Liang Junpin Lin State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China Cast Titanium Alloy R&D Center Beijing Institute of Aeronautical MaterialsBeijing 100095China

This study investigates the phase constitutions and transformations that occur in the mushy zone and in the adjacent phase fields of a directionally solidified Ti-44Al-8Nb-1Cr alloy via quenching *** results indicate that the mushy zone consists of unmeltedβdendrites and interdendritic liquid,whose formation can be attributed to the difference in melting point aroused by local heterogeneity in ***βdendrite is composed of numerous subgrains with various *** quenching,theβdendrite transforms into Widmanstättenαvia a precipitation reaction,owing to the decreasing cooling rate caused by heat transfer from the surrounding ***,after quenching,the interdendritic liquid is transformed intoγ*** the singleβphase field and the lower part of the mushy zone,a massive transformation ofβtoγ***,in theβ+αphase field,bothβandαphases are retained to ambient *** the heating process,the transformation ofα→βgives rise to the formation ofβvariants,which affects the orientation ofβdendrites in the mushy *** growth kinematics of theα→βtransformation was elucidated,revealing the preferential growth directions of111and112forβ***,this study presents an illustration of the formation process of the mushy zone and the microstructural evolution during the heating and quenching process.

关键词： Titanium aluminides Mushy zone Quenching Electron backscattering diffraction phase transformation

Multi-scale analyses of phase transformation mechanisms and hardness in linear friction welded Ti17(a+β)/Ti17(β)dissimilar titanium alloy joint

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Chinese Journal of Aeronautics 2024年第1期37卷 312-324页

作者： Zhenguo GUO Tiejun MA Xiawei YANG Ju LI Wenya LI Achilles VAIRIS State Key Laboratory of Solidification Processing Shaanxi Key Laboratory of Friction Welding TechnologiesNorthwestern Polytechnical UniversityXi’an 710072China Aeronautical Key Laboratory for Welding and Joining Technologies AVIC Manufacturing Technology InstituteBeijing 100024China Mechanical Engineering Department University of West AtticaAthens 12241Greece

The Ti17(a+β)-Ti17(β)dual alloy-dual property blisk produced using Linear Friction Welding(LFW)is considered as high-performance component in advanced ***,up to now,microstructure evolution and relationship between microstructure and micro mechanical properties of LFWed Ti17(a+β)/Ti17(β)dissimilar joint have not been thoroughly *** this work,complex analyses of the phase transformation mechanisms of the joint are conducted,and phase transformations in individual zones are correlated to their microhardness and *** reveal that a dissolution occurs under high temperatures encountered during LFW,which reduces microhardness of the joint to that of Ti17(a+β)and Ti17(β).In ThermoMechanically Affected Zone of Ti17(a+β)(TMAZ-(a+β))side joint,a large number of nanocrystalline a phases form with different *** microstructure strengthens significantly by fine grains which balances partial softening effect of a dissolution,and increases nanohardness of a phase and microhardness of TMAZ-(a+β).Superlattice metastableβphase precipitates from metastableβin Weld Zone(WZ)during quick cooling following welding,because of short-range diffusion migration of solute atoms,especiallyβstabilizing elements Mo and *** precipitation of the superlattice metastableβphase results in precipitation strengthening,which in turn increases nanohardness of metastableβand microhardness in WZ.

关键词： Linear friction welding Ti17 titanium alloy phase transformation Microhardness Nanohardness

Preparation of NiTip/Al composites with controllable phase transformation and damping behavior by friction stir processing

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Science China(Technological Sciences) 2024年第2期67卷 597-607页

作者： WU Xiao JIANG HongJie LI WangYun LIU ChongYu HUANG HongFeng LIU ShuHui WEI LiLi School of Material Science and Engineering Guilin University of Technology Guilin 541004China Key Laboratory of New Processing Technology for Nonferrous Metal&Materials Ministry of EducationGuilin University of Technology Guilin 541004China School of Mechanical and Electrical Engineering Guilin University of Electronic TechnologyGuilin 541004China

The NiTip/1060Al composites were prepared using a pre-aging and friction stir method(FSP)to enhance the low-temperature damping performance of the aluminum alloy and accommodate various service *** bonding between NiTi particles and the 1060Al matrix is well established after FSP,and no new phases are formed in the *** phasetransformation peak temperature of NiTip/1060Al composites gradually shifts to lower temperatures with increased aging temperature of NiTi *** room temperature,the 550℃-NiTip/1060Al composite exhibits superior damping performance,with an internal friction value 144%higher than that of the FSP-1060Al ***,at-91℃,the 650℃-NiTip/1060Al composite demonstrates better damping performance,with an internal friction value 158%higher than that of the FSP-1060Al *** NiTip/1060Al composites exhibit the internal friction peak of NiTi phase-transformation in the temperature range from-91℃to 60℃.This characteristic results in significantly better damping performance compared to the FSP-1060Al alloy and other high-damping aluminum matrix composites.

关键词： NiTi particle aluminum matrix composites phase transformation damping behavior friction stir processing

Disordered Structure and Reversible phase transformation from K-Birnessite to Zn-Buserite Enable High-Performance Aqueous Zinc-Ion Batteries

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Energy & Environmental Materials 2024年第3期7卷 104-115页

作者： Nibagani Naresh Suyoon Eom Sang Jun Lee Su Hwan Jeong Ji-Won Jung Young Hwa Jung Joo-Hyung Kim Department of Materials Engineering and Convergence Technology Gyeongsang National University(GNU) School of Material Science and Engineering (Ceramic Engineering) Gyeongsang National University (GNU)Jinju 52828South Korea School of Materials Science and Engineering University of Ulsan (UOU) PLS-Ⅱ Beamline Division Pohang Accelerator Laboratory(PAL)

The layered δ-MnO2（dMO） is an excellent cathode material for rechargeable aqueous zinc-ion batteries owing to its large interlayer distance （～0.7 nm）,high capacity,and low cost; however,such cathodes suffer from structural degradation during the long-term cycling process,leading to capacity *** this study,a Co-doped dMO composite with reduced graphene oxide（CC-dMO） is developed using a simple cost-effective hydrothermal *** degree of disorderness increases owing to the hetero-atom doping and graphene oxide *** is demonstrated that layered dMO and CC-dMO undergo a structural transition from K-birnessite to the Zn-buserite phase upon the first discharge,which enhances the intercalation of Zn2+ions,H2O molecules in the layered *** CC-dMO cathode exhibits an excellent capacity of 302mAhg-1at a current density of 100mAg-1after100 cycles as compared with the dMO cathode (159mAhg-1).The excellent electrochemical performance of the CC-dMO cathode owing to Co-doping and graphene oxide sheets enhances the interlayer gap and disorderness,and maintains structural stability,which facilitates the easy reverse intercalation and de-intercalation of Zn2+ions and H2O ***,CC-dMO is a promising cathode material for large-scale aqueous ZIBs.

关键词： aqueous zinc-ion batteries birnessite buserite disordered structure phase transformation

phase transformation in Al/Zn Multilayers during Mechanical Alloying

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Acta Metallurgica Sinica(English Letters) 2023年第10期36卷 1709-1718页

作者： Chen Chen Junjie Yu Jingyu Lu Jian Zhang Xuan Su Chen-Hao Qian Yulin Chen Weixi Ji Manping Liu Department of Mechanical Engineering Jiangnan UniversityWuxi214122China Jiangsu Key Laboratory of Advanced Food Manufacturing Equipment and Technology Jiangnan UniversityWuxi214122China School of Materials Science and Engineering Jiangsu UniversityZhenjiang212013China

In this work,mechanical alloying of the alternating stacked pure Al and Zn thin foils was accomplished via high-pressure torsion(HPT).In the alloyed Al-Zn system,an exotic phase transformation from hexagonal close-packed(HCP)to face-centered cubic(FCC)was *** atomic-scale evolution process and underlying mechanism of phase transformation down to atomic scale are provided by molecular dynamics simulation and high-resolution transmission electron *** HCP→FCC phase transformation was attributed to the sliding of Shockley partial dislocations generated at the Al-Zn grain boundaries,which resulted in an[2110][011]and(0001)/(111)orientation relationship between the two *** work provides a new approach for the in-depth study of the solid phase transformation of Al-Zn alloys and also shed lights on understanding the mechanical properties of the HPT processed Al-Zn alloys.

关键词： High-pressure torsion phase transformation Al/Zn multilayers Mechanical alloying

phase transformation in suspension roasting of oolitic hematite ore

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Journal of Central South University 2015年第12期22卷 4560-4565页

作者：李艳军王儒韩跃新魏新超 School of Resources and Civil Engineering Northeastern University College of Engineering The State University of New York Polytechnic Institute

Suspension roasting followed by magnetic separation is a promising method to upgrade oolitic hematite *** oolitic hematite ore was roasted using suspension roasting technology at different *** phase transformation for iron minerals was investigated by XRD and Mossbauer spectrum,and the characteristics of roasted product were analyzed by VSM and *** indicate that the magnetic concentrate is of 58.73% Fe with iron recovery of 83.96% at 650 °*** hematite is rapidly transformed into magnetite during the roasting with transformation ratio of 92.75% at 650 °*** temperature has a significant influence on the phase transformation of hematite to *** transformation ratio increases with increased *** roasting,the magnetic susceptibility is significantly improved,while iron ore microstructure is not altered significantly.

关键词： oolitic hematite ore suspension roasting Mossbauer spectrum magnetic property phase transformation

phase transformation of Nanosized Zirconia

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Chinese Journal of Structural Chemistry 2006年第4期25卷 424-432页

作者：刘欣梅阎子峰 State Key Laboratory of Heavy Oil Processing CNPC Key Laboratory of Catalysis China University of Petroleum Dongying 257061 China

The nanosized zirconia was synthesized via solid state reaction in the presence of surfactant. The results indicate that crystal phase of zirconia can be controlled by tuning the synthesis parameters such as OH^-/Zr molar ratio, crystallizing temperature and time. It can be transformed among amorphous, tetragonal and monoclinic phases. The transformation is driven by particle size. The research shows the nanocrystalline zirconia possesses the higher thermal stability compared with amorphous framework. The ＂glow exotherm＂ can be observed for the amorphous samples. Otherwise, it is in the absence for nanocrystalline samples. Herein, the reason for retention of tetragonal zirconia is demonstrated.

关键词： solid state reaction zirconia nanosize phase transformation

phase transformation at controlled locations in nanowires by in situ electron irradiation

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Nano Research 2020年第7期13卷 1912-1919页

作者： Hongtao Zhang Wen Wang Tao Xu Feng Xu Litao Sun SEU-FEI Nano-Pico Center Key Laboratory ofMEMS of Ministry of EducationSoutheast UniversityNanjing 210096China Center for Advanced Materials and Manufacture Southeast University-Monash University Joint Research InstituteSuzhou 215123China

Solid state phase transtormations have drawn great attention because they can be effectively exploited to control the microstructure and property of *** the physics of such phase transformation processes is critical to designing materials with controlled structure and with desired ***,in traditional ex situ experiments,it is hard to achieve position controlled phase transformations or obtain desirable crystal phase on nanometer *** the underlying mechanisms of the reaction processes are not fully understood due to the lack of direct and real-time *** this paper,we observe phase transformation from body-centered tetragonal PX PbTiO3 to monclinic TiO2(B)on the atomic scale by in situ electron iradiation during heat treatment in transmission electron microscope,at pre-defined locations on the *** demonstrate that by controlling the location of the incident electron beam,a porous TiO2(B)crystal structure can be formed at the desired area on the nanowire,which is dificult to achieve by traditional synthesis *** in situ heating,the Pb atoms in the crystal migrate out of the pristine nanowire through inelastic scattering under incident electrons while high temperature(>400℃)provides energy for the crytalization of TiO2(B)and the vlatlization of a substantial number of Pb atoms,which makes the resultingTiO2(B)nanowires to be *** contrast,at temperaturesphase transition from the PX-PbTiO3 to monoclinic TiO2(B),but also suggests a crystallography engineering strategy to obtain the desired crystal phase at controlled locations on the nanometer scale.

关键词： phase transformation controlled locations in situ transmission electron microscopy