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Enhanced Grain Refining Effect of Mg–Zr Master Alloy on Magnesium Alloys via a Synergistic Strategy Involving heterogeneous nucleation and Solute‑Driven Growth Restriction

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Acta Metallurgica Sinica(English Letters) 2024年第8期37卷 1354-1366页

作者： Gang Zeng Hong Liu Jing‑Peng Xiong Jian‑Long Li Yong Liu Key Laboratory of Lightweight and High Strength Structural Materials of Jiangxi Province School of Advanced ManufacturingNanchang UniversityNanchang 330031China

Zirconium(Zr)emerges as the most effective grain refiner for magnesium(Mg)alloys incorporating ***,Zr is introduced in the form of an Mg–Zr master ***,within Mg–Zr master alloys,Zr predominantly exists in a particle form,which tends to aggregate due to attractive van der Waals *** clustered Zr is prone to settling,thereby reducing its refining impact on Mg *** this work,a combined pretreatment process for Mg–Zr master alloys was proposed,encompassing the introduction of a physical field to intervene the agglomeration of particle Zr and the employ of high-temperature dissolution and peritectic reactions to promote the solid solution of *** results demonstrate that the particle Zr within the pretreated Mg–Zr master alloy is effectively dispersed and refined,and greater solute Zr levels can be *** subsequent grain refinement ability was studied on a typical Mg–6Zn–0.6Zr(wt%)*** outcome highlights that an improvement in the grain refinement efficacy(32.4%)of Mg–Zr master alloys was obtained with a holding time of 60 *** pretreated Mg–Zr master alloy significantly augments the efficiency of grain refinement for Mg alloys through a synergistic strategy involving heterogeneous nucleation and solute-driven growth *** crucial factor in achieving effective grain refinement of Zr in Mg alloys lies in regulating the presence and morphology of Zr in the Mg–Zr master alloy,distinguishing between particle Zr and solute *** study introduces a novel method for developing more efficient Mg–Zr refiners.

关键词： Magnesium alloy Mg-Zr master alloy Grain refinement heterogeneous nucleation Solute-driven growth restriction Synergistic strategy

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Enhancing reversible hydrogen storage performance of 2LiBH4–MgH2 via in-situ building heterogeneous nucleation sites

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Rare Metals 2024年第9期43卷 4367-4376页

作者： Wei Chen Ya-Hui Sun Tian Xu Xue-Bin Yu Guang-Lin Xia Department of Materials Science Fudan University

2LiBH4-MgH2composite is one of the most attractive reactive hydride composites with a theoretic hydrogen capacity of 10.8 wt%.However,the large nucleation restriction of MgB2during the second step of dehydrogenation results in sluggish hydrogen storage kinetics and high operating temperature,which hinders its practical application as on-board hydrogen storage ***,Al3Ti doped Al nanoparticles （AT NPs） are prepared by a facile chemical reduction reaction to improve the hydrogen storage performance of *** the initial H2desorption process,MgAlB4and TiB2that have identical crystal structure and low d-value mismatch with MgB2resulting from the reaction between AT NPs and 2LiBH4-MgH2composite serve as effective nucleation sites for the formation of *** a result,the apparent activation energy of the two-step H2desorption of AT NPs doped 2LiBH4-MgH2composite are notably decreased to （110.0±5.9） and（119.6±1.4） kJ·mol-1,which is 55.5 and 33.5 kJ·mol-1lower than that of the undoped *** importantly,a reversible hydrogen storage capacity of 9.2 wt%after 10cycles of H2desorption and adsorption could be achieved,corresponding to a capacity retention rate of 99%.The building of reactive bimetallic catalyst towards in situ formation of heterogeneous nucleation sites provides a new strategy for improving the hydrogen storage performance of reactive hydride composites.

关键词： Catalytic effects heterogeneous nucleation Reactive hydride composites Reversible hydrogen storage

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Atomic insights into heterogeneous nucleation and growth kinetics of Al on TiB_(2) particles in undercooled Al-5Ti-1B melt

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Journal of Materials Science & Technology 2023年第25期156卷 72-82页

作者： Jing Feng Yanfeng Han Xiaocang Han Xiaodong Wang Shuangxi Song Baode Sun Mingwei Chen Pan Liu Shanghai Key Laboratory of Advanced High-temperature Materials and Precision Forming State Key Laboratory of Metal Matrix Composites School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Department of Materials Science and Engineering Johns Hopkin UniversityBaltimoreMD 21218USA

Titanium diboride(TiB_(2))is an effective grain refiner of Al alloys in the industry that facilitates casting processes by forming uniformly refined *** our understanding of the underlying refinement mechanisms has advanced,the atomic kinetics of heterogeneous nucleation of Al on TiB2 remains ***,we report atomic-scale observations of the heterogeneous nucleation and growth kinetics of Al on self-formed TiB_(2) particles by in situ heating of undercooled Al-5Ti-1B *** demonstrate that an ordered Al monolayer forms on the Ti-terminated{0001}TiB_(2) surface;then,the surrounding Al atoms are initiated to form an island-shaped Al nucleus with face-centered cubic{111}stacking without the assistance of a Ti-rich buffer *** interfacial lattice mismatch between{111}Al and{0001}TiB_(2) causes remarkable out-of-plane strain that decreases gradually with Al nucleus layers increasing to 6 atomic *** elastic strain energy originating from this interfacial strain increases the free energy of the Al/TiB2 heterostructure,hence impeding the rapid growth of the Al *** found that TiB2 particles stabilize the Al nuclei rather than activating their free growth into grains when the experimental undercoolingΔT is lower than the onset undercoolingΔT fg in Greer's free growth *** findings provide an atomic-scale physical image of the heterogeneous nucleation and growth mechanisms of Al with inoculator participation and elucidate the strain-dependent growth kinetics of Al nuclei.

关键词： In situ tem heterogeneous nucleation Lattice strain Aluminum TiB2 particles

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7YSZ coating prepared by PS-PVD based on heterogeneous nucleation

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Chinese Journal of Aeronautics 2018年第4期31卷 820-825页

作者： Ziqian DENG Xiaofeng ZHANG Kesong ZHOU Min LIU Chunming DENG Jie MAO Zhikun CHEN School of Materials and Energy Guangdong University of Technology Guangzhou 510006 China National Engineering Laboratory for Modern Materials Surface Engineering Technology & the Key Lab of Guangdong for Modern Surfuce Engineering Technology Guangdong Institute of New Materials Guangzhou 510650 China School of Materials Science and Engineering South China University of Technology Guangzhou 510640 China

Plasma spray-physical vapor deposition（PS-PVD） as a novel coating process based on low-pressure plasma spray（LPPS） has been significantly used for thermal barrier coatings（TBCs）.A coating can be deposited from liquid splats, nano-sized clusters, and the vapor phase forming different structured coatings, which shows obvious advantages in contrast to conventional technologies like atmospheric plasma spray（APS） and electron beam-physical vapor deposition（EBPVD）. In addition, it can be used to produce thin, dense, and porous ceramic coatings for special applications because of its special characteristics, such as high power, very low pressure, etc. These provide new opportunities to obtain different advanced microstructures, thus to meet the growing requirements of modern functional coatings. In this work, focusing on exploiting the potential of gas-phase deposition from PS-PVD, a series of 7 YSZ coating experiments with various process conditions was performed in order to better understand the deposition process in PS-PVD, where coatings were deposited on different substrates including graphite and zirconia. Meanwhile, various substrate temperatures were investigated for the same substrate. As a result, a deposition mechanism of heterogeneous nucleation has been presented showing that surface energy is an important influencing factor for coating structures. Besides, undercooling of the interface between substrate and vapor phase plays an important role in coating structures.

关键词： 7YSZ Deposition mechanism heterogeneous nucleation PS-PVD TBC

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Effects of alloying elements X( X = Zr,V,Cr,Mn,Mo,W,Nb,Y) on ferrite/TiC heterogeneous nucleation interface: first-principles study

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Journal of Iron and Steel Research International 2017年第3期24卷 328-334页

作者： Hui-hui Xiong Heng-hua Zhang Hui-ning Zhang Yang Zhou State Key Laboratory of Advanced Special Steel Shanghai Key Laboratory of Advanced FerrometallurgySchool of Materials Science and EngineeringShanghai University School of Metallurgy and Chemical Engineering Jiangxi University of Science and Technology

The segregation behavior of alloying elements X（ X = Zr,V,Cr,Mn,Mo,W,Nb,Y） on the ferrite（ 100） /TiC（ 100） interface has been investigated using first principles method,and the work of separation and interface energy of ferrite / TiC interfaces alloyed by these elements were also analyzed. The results indicated that all these alloying additives except Y were thermodynamically favorable because of the negative segregation energy,showing that they have the tendency to segregate to the ferrite / TiC interface. When the Fe atom in the ferrite /TiC interface is replaced by Y,Zr,or Nb,the adhesive strength of the interface will be weakened due to the lower separation work,larger interfacial energy,and weaker electron effects. However,the introduction of Cr,Mo,W,Mn and V will improve the stability of the ferrite / TiC interface through strong interaction between these elements and C,and Cr-doped interface is the most stable structure. Therefore,the Cr,Mo,W,Mn and V in ferrite side of the interface can effectively promote ferrite heterogeneous nucleation on TiC surface to form fine ferrite grain.

关键词： Fe/TiC interface Alloying element heterogeneous nucleation Segregation First-principles

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Simultaneous refinement of α-Mg grains and β-Mg_(17)Al_(12) in Mg-Al based alloys via heterogeneous nucleation on Al_(8)Mn_(4)Sm

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Journal of Magnesium and Alloys 2023年第1期11卷 348-360页

作者： Jun-Chen Chen Mei-Xuan Li Zhi-Yang Yu Zhao-Yuan Meng Cheng Wang Zhi-Zheng Yang Hui-Yuan Wang State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130012PR China Key Laboratory of Automobile Materials of Ministry of Education&School of Materials Science and Engineering Jilin UniversityNanling CampusNo.5988 Renmin StreetChangchun 130025PR China International Center of Future Science Jilin UniversityChangchun 130012PR China

Due to the significant differences in the formation temperature and crystal structure between the primaryα-Mg and eutecticβ-Mg_(17)Al_(12),it is a great challenge to achieve simultaneous refinement of the primary and eutectic phases in Mg-Al based alloys via heterogeneous ***,we found that theα-Mg andβ-Mg_(17)Al_(12) in the AZ80 alloy can be simultaneously refined after 0.2 wt.%Sm addition,with the grain size decreasing from∼217±15μm to∼170±10μm and theβ-Mg_(17)Al_(12) morphology changing from a typical continuous network to a nod-like or spherical *** simultaneous refinement mechanism is investigated through solidification simulation,transmission electron microscopy(TEM),and differential thermal analysis(DTA).In the AZ80-0.2Sm alloy,many Al8Mn4Sm particles can be observed near the center of theα-Mg grains or inside theβ-Mg_(17)Al_(12).Crystallographic calculations further reveal that the Al8Mn4Sm has good crystallographic matching with both theα-Mg andβ-Mg_(17)Al_(12),so it possesses the potency to serve as heterogeneous nucleation sites for both *** promoted heterogeneous nucleation on the Al8Mn4Sm decreases the undercooling required by the nucleation of the primary and eutectic phases,which enhances the heterogeneous nucleation rate,thus causing the simultaneous refinement of theα-Mg andβ-Mg_(17)Al_(12).The orientation relationships between the Al8Mn4Sm and Mg/Mg_(17)Al_(12) are identified,which are[1210]_(Mg)//[010]_(Al8Mn4Sm),(1010)_(Mg)//(301)_(Al8Mn4Sm) and[112]_(Mg_(17)Al_(12))//[010]_(Al8Mn4Sm),(110)_(Mg_(17)Al_(12))//(301)_(Al8Mn4Sm),***,the refinement of theβ-Mg_(17)Al_(12) accelerates its dissolution during the solution treatment,which is beneficial for cost saving in industrial *** Al8Mn4RE compounds such as Al8Mn4Y might have the same positive effect on the simultaneous refinement due to the similar physicochemical properties of rare earth *** work not only proves the po

关键词： Magnesium alloys Microstructure refinement Primaryα-Mg Eutecticβ-Mg_(17)Al_(12) Rare earth heterogeneous nucleation

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Experimental determination of grain density function of AZ91/SiC composite with different mass fractions of SiC and undercoolings using heterogeneous nucleation model

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China Foundry 2011年第1期8卷 101-106页

作者： J.Lelito P.Zak J.S.Suchy W.Krajewski A.L.Greer P.Darlak Department of Foundry Engineering Processes AGH University of Science and Technology Department of Materials Science & Metallurgy University of Cambridge Foundry Institute

The grain density,Nv,in the solid state after solidification of AZ91/SiC composite is a function of maximum undercooling,ΔT,of a liquid *** type of function depends on the characteristics of heterogeneous nucleation sites and number of SiC present in the *** aim of this paper was selection of parameters for the model describing the relationship between the grain density of primary phase and *** model in connection with model of crystallisation,which is based on chemical elements diffusion and grain interface kinetics,can be used to predict casting quality and its *** models have parameters,which exact values are usually not known and sometimes even their physical meaning is under *** parameters can be obtained after mathematical analysis of the experimental *** composites with 0,1,2,3 and 4wt.% of SiC particles were *** AZ91 alloy was a matrix of the composite reinforcement SiC *** composite was cast to prepare four different thickness *** were taken from the region near to the thermocouple,to analyze the undercooling for different composites and thickness plates and its influence on the grain *** microstructure and thermal analysis gave set of values that connect mass fraction of SiC particles,and undercooling with grain *** values were used to approximate nucleation model adjustment *** model can be very useful in modelling composites microstructure.

关键词： heterogeneous nucleation mass fraction of SiC particles AZ91/SiC composite grain density mathematical modelling

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Effect of substrate micro-morphology on heterogeneous nucleation

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China Foundry 2012年第3期9卷 234-238页

作者： Zhang Ying Wang Meng Lin Xin Huang Weidong State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072ShaanxiChina

The heterogeneous nucleation process of NH4Cl crystals from a NH4Cl-70wt.%H2O solution on rough chilling substrates was considered in this paper. Scratched and etched substrates of aluminum were prepared with different surface morphologies. It was concluded that for nucleation to occur on a rough substrate surface, the wettability or the generally said roughness are not the key factors affecting the heterogeneous nucleation process. Rather the surface morphologies on the nanometer scale, which is close to the scale of the critical nucleation radius, are more important.

关键词： grain refinement heterogeneous nucleation substrate micro-morphology

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Integration of homogeneous and heterogeneous nucleation growth via 3D alloy framework for stable Na/K metal anode

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eScience 2021年第1期1卷 75-82页

作者： Shufen Ye Lifeng Wang Fanfan Liu Pengcheng Shi Yan Yu Hefei National Laboratory for Physical Sciences at the Microscale Department of Materials Science and EngineeringNational Synchrotron Radiation LaboratoryCAS Key Laboratory of Materials for Energy ConversionUniversity of Science and Technology of China.HefeiAnhui 230026China School of Materials and Energy Guangdong University of TechnologyGuangzhouGuangdong510006China

Sodium/Potassium(Na/K)metal anodes have been considered as the promising anodes for next-generation Na/K secondary batteries owing to their ultrahigh specific capacity,low redox potential and low ***,their practical application is still hampered due to unstable solid electrolyte interphase,infinite volume change,and dendrite ***,we design a 3D-Na_(3)Bi/3D-K_(3)Bi alloy host which enables the homogeneous and heterogeneous nucleation growth of Na/K *** unique structure with periodic alternating of electron and ion conductivity improves the mass transfer kinetics and prevents the volume expansion during ***,the sodiophilicity of Na_(3)Bi/potassiophilicity of K_(3)Bi framework can avoid dendritic *** lifespans over 700 h with 1 mAh cm^(−2)for 3D-Na_(3)Bi@Na electrode and about 450 h with 1 mAh cm^(−2)for 3D-K_(3)Bi@K electrode are achieved,respectively.3D-Na_(3)Bi@Na||Na_(3)V_(2)(PO_(4))3 full battery shows sustainable cycle performance over 400 *** design provides a simple but effective approach for achieving safety of sodium/potassium metal anodes.

关键词： Na/K metal anode 3D host structure Homogeneous nucleation heterogeneous nucleation Na_(3)Bi/K_(3)Bi

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Graphite Surface Modification by heterogeneous nucleation Process

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China's Refractories 2006年第3期15卷 6-9页

作者： CAO Ran LI Hongxia Sinosteel Luoyang Institute of Refractories Research Luoyang 471039

Flaky graphite particles were coated by ZrOCl2 · 8H2O as precursors by heterogeneous nucleation process. The effects of factors such as pH values （ 2. 4 - 5. 1 ）, concentration of the precursor solution （ 0. 005 - 0. 1 mol · L^-1） , mixing method of graphite and precursor solution on the surface modification of graphite were studied. Result shows that ：1 ） the preferable technical process for heterogeneous nucleation modified graphite is to mix the graphite suspension and precursor solution with concentration 0. 025 mol ·L^-1 and then drip ammonia water to adjust the pH value to 3.6 ; 2 ） By surface modification, the ZrO2 particles are evenly coated on graphite surface and therefore improve oxidation resistance and dispersion ability of graphite.

关键词： Graphite Surface modification heterogeneous nucleation Zirconia Oxidation resistance

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