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phase transformation behavior of a dual-phase nanostructured Fe-Ni-B-Si-P-Nb metallic glass and its correlation with stress-impedance properties

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稀有金属:英文版 2023年第8期42卷 2757-2766页

作者： Jia-Cheng Ge Ai-Hua Liu Zhen-Duo Wu Yao Gu Yu-Bin Ke An-Ding Wang Yang Ren Song Tang Hui-Qiang Ying He Zhu Xun-Li Wang Si Lan Herbert Gleiter Institute of Nanoscience School of Materials Science and EngineeringNanjing University of Science and TechnologyNanjing 210094China Department of Physics City University of Hong KongHong Kong999077China City University of Hong Kong(Dongguan) Dongguan 523000China Center for Neutron Scattering City University of Hong Kong Shenzhen Research InstituteShenzhen 518057China Spallation Neutron Source Science Center Dongguan 523803China Guangdong-Hong Kong-Macao Joint Laboratory for Neutron Scattering Science and Technology Dongguan 523803China School of Materials Science and Engineering Dongguan University of TechnologyDongguan 523808China

A study of the phase transformation process of a Fe-Ni-B-Si-P-Nb metallic glass using a suite of advanced characterization tools is reported.Transmission electron microscopy(TEM)and small angle neutron scattering(SANS)experiments show that the as-spun metallic glass ribbon has a dual-phase structure with bcc nanoclusters of a size of 2-3 nm.In situ high-energy X-ray diffraction(XRD)reveals a three-stage crystallization process when heating the metallic glass into supercooled liquid states.The isothermal annealing experiment shows the nanoclusters grow instantly without incubation.The easy formation and phase stability of the nanoclusters are due to the low interfacial energy between the amorphous matrix and clusters,as real space analysis shows that the nanoclusters and the amorphous matrix share similar short-to-mediumrange orders.We further find that the dual-phase structure reduces local magneto-anisotropy and enhances effective magnetic permeability,resulting in an excellent stressimpedance effect without sacrificing coercivity.Our work sheds light on the structure-property engineering of soft magnetic metallic glasses and provides a foundation for developing novel magnetic functional materials with nanostructured dual-phases.

关键词： Soft-magnetic property Metallic glass phase transformation Synchrotron and neutron scattering Stressimpedance(SI)

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 identified.The 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 microscopy.The 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 phases.This 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 and structural evolution in a Ti-5at.%Al alloy induced by cold-rolling

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Journal of Materials Science & Technology 2020年第14期47卷 211-223页

作者： Bingqiang Wei Song Ni Yong Liu Xiaozhou Liao Min Song State Key Laboratory of Powder Metallurgy Central South UniversityChangsha 410083China School of Aerospace Mechanical and Mechatronic EngineeringThe University of SydneySydneyNSW 2006Australia

The phase transformation,deformation mechanism and their correlation in a cold-rolled Ti-5 at.%Al alloy were investigated.Two types of phase transformations from a hexagonal close-packed(HCP)structure to a face-centered cubic(FCC)structure were observed:the basal-type(B-type)with an orientation relation-ship oftransformations both accommodate the strain along theaxis of the HCP matrix.With the proceeding of deformation,different deformation mechanisms were activated in the FCC and the HCP structures,respectively,which led to a faster grain refinement rate in the FCC structure than in the HCP matrix.Deformation twins with zero macroscopic strain were prevalent in the FCC domains produced by the B-type transformation,while deformation twins with macroscopic strain were normally observed in the FCC domains produced by the P-type transformation.This is in accordance with the lattice mismatches produced during phase transformation.The easy occurrence of deformation twinning in the FCC structure contributed significantly to the grain refinement process.In addition,the interaction between neighboring FCC domains produced by the two types of phase transformations also accelerated the grain refinement process.

关键词： Ti-Al alloy Deformation mechanism phase transformation Grain refinement Deformation twinning

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 materials.Understanding the physics of such phase transformation processes is critical to designing materials with controlled structure and with desired properties.However,in traditional ex situ experiments,it is hard to achieve position controlled phase transformations or obtain desirable crystal phase on nanometer scale.Meanwhile the underlying mechanisms of the reaction processes are not fully understood due to the lack of direct and real-time observation.In 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 sample.We 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 methods.Upon 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 porous.In 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

phase transformation under Continuous Cooling Conditions in Medium Carbon Microalloyed Steels

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Journal of Materials Science & Technology 2014年第5期30卷 511-516页

作者： Manuel Gomez Lucia Rancel Esther Escudero Sebastian F.Medina National Centre for Metallurgical Research CENIM-CSICAv.Gregorio del Amo 828040 MadridSpain

Several 35CrMo4 and 38MnV7 steels with different additions of Ti and V were manufactured by electroslag remelting. The influence of the alloying and microalloying elements on phase transformation at different cooling rates was studied and the continuous cooling transformation diagrams were plotted. In order to optimize the heat treatment and improve the mechanical properties, the range of cooling rates leading to a fully bainitic microstructure （without ferrite, pearlite and especially without martensite） was determined. Bainite and martensite transformation start temperatures （Bs, Ms） were also established and compared with the values predicted by empirical equations. The important role of precipitates （especially V carbonitride particles） on final microstructure and mechanical properties was assessed.

关键词： Microalloyed steel phase transformation Precipitation Dilatometry Continuous cooling transformation diagram

phase transformation kinetics of Ti-1300 alloy during continuous heating

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Rare Metals 2015年第4期34卷 233-238页

作者： Ming-Pan Wan Yong-Qing Zhao Wei-Dong Zeng State Key Laboratory of Solidification Processing Northwest Polytechnical University College of Materials and Metallurgy Guizhou University Northwest Institute for Nonferrous Metal Research

Abstract The α ＋ β→β phase transformation kinetics of Ti-1300 alloy during continuous heating at different heating rates were investigated using dilatometric method. Results show that the curves of the α ＋ β→β phase transformation exhibit a typical S-shaped pattern, which indicates that the α ＋ β→β phase transformation is a nucleation-growth-controlled process. The overall activation energy of the α ＋ β→β transformation of the alloy is 797 kJ·mol^-1. The nucleation and growth mechanism of the α ＋ β→β transformation was also investigated using the non-isothermal Avrami exponent. The Avrami exponent during α ＋ β→β transformation process significantly changes with transformed volume fraction increasing, which indicates that the α ＋ β→β transformation mechanism in the Ti-1300 alloy varies at different sections.

关键词： Ti-1300 alloy phase transformation Dilatometry Kinetics

phase transformation from cubic ZnS to hexagonal ZnO by thermal annealing

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Journal of Semiconductors 2015年第3期36卷 19-22页

作者： K.Mahmood M.Asghar N.Amin Adnan Ali Department of Physics GC University Faisalabad Department of Physics The Islamia University of Bahawalpur

We have investigated the mechanism of phase transformation from ZnS to hexagonal ZnO by high- temperature thermal annealing. The ZnS thin films were grown on Si （001） substrate by thermal evaporation system using ZnS powder as source material. The grown films were annealed at different temperatures and characterized by X-ray diffraction （XRD）, photoluminescence （PL）, four-point probe, scanning electron microscope （SEM） and energy dispersive X-ray diffraction （EDX）. The results demonstrated that as-deposited ZnS film has mixed phases but high-temperature annealing leads to transition from ZnS to ZnO. The observed result can be explained as a two- step process：（1） high-energy O atoms replaced S atoms in lattice during annealing process, and （2） S atoms diffused into substrate and/or diffused out of the sample. The dissociation energy of ZnS calculated from the Arrhenius plot of 1000/T versus log （resistivity） was found to be 3.1 eV. PL spectra of as-grown sample exhibits a characteristic green emission at 2.4 eV of ZnS but annealed samples consist of band-to-band and defect emission of ZnO at 3.29 eV and 2.5 eV respectively. SEM and EDX measurements were additionally performed to strengthen the argument.

关键词： ZnS phase transformation EDX XRD PL

phase transformation During Intercritical Tempering with High Heating Rate in a Fe-13%Cr-4%Ni-Mo Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2013年第6期26卷 669-674页

作者： Pei WANG Shenghua ZHANG Shanping LU Dianzhong LI Yiyi LI Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences

The phase transformation from martensite to austenite during intercritical tempering with high heating rate in a low carbon martensitic stainless steel Fe-13%Cr-4%Ni-Mo has been investigated to clarify the microstructure evolution in some regions of the weld joint heat affected zone （HAZ）. The experimental results indicate that the start and finish temperatures of the martensite to austenite transformation keep constant when the heating rate is higher than 10 K/s, and the transformation is much faster than nickel diffusion. The mechanism of the martensite to austenite transformation changes from diffusion to diffusionless during the intercritical tempering when the heating rate is higher than 10 K/s. The diffusionless transformation and higher As temperature render it difficult for any austenite to remain at room temperature during the intercritical tempering with high heating rate that occurs in the HAZ. Adding a proper intercritical tempering with low heating rate can induce some reversed austenite in the rapid heated sample.

关键词： Martensitic stainless steel phase transformation Intercritical tempering Heating rate Microstructure

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 resources.According 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