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The anisotropic grain size effect on the mechanical response of polycrystals:The role of columnar grain morphology in additively manufactured metals

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Journal of Materials Science & Technology 2024年第14期181卷 240-256页

作者： S.Amir H.Motaman Dilay Kibaroglu Institut für Eisenhüttenkunde RWTH Aachen UniversityIntzestraße 1Aachen 52072Germany

Additively manufactured(AM)metals exhibit highly complex microstructures,particularly in terms of grain morphology which typically features heterogeneous grain size distribution,irregular and anisotropic grain shapes,and the so-called columnar *** conventional morphological descriptors based on grain shape idealization are generally inadequate for representing complex and anisotropic grain mor-phology of AM *** primary aspect of microstructural grain morphology is the state of grain boundary spacing or grain size whose effect on the mechanical response is known to be *** this paper,we formally introduce the notion of axial grain size from which we derive mean axial grain size,effective grain size,and grain size anisotropy as robust morphological descriptors ca-pable of effectively representing highly complex grain *** instantiated a discrete sample of polycrystalline aggregate as a representative volume element(RVE)featuring random crystallographic orientation and misorientation ***,the instantiated RVE incorporates the typical mor-phological features of AM microstructures including distinctive grain size heterogeneity and anisotropic grain size owing to its pronounced columnar grain *** ensured that any anisotropy ob-served in the macroscopic mechanical response of the instantiated sample primarily originates from its underlying anisotropic grain *** RVE was then employed for mesoscale full-field crystal plasticity simulations corresponding to uniaxial tensile deformation along various axes via a spectral solver and a physics-based crystal plasticity constitutive model which was developed,calibrated,and validated in ear-lier *** the numerical analyses,we isolated the contribution of anisotropic grain size to the anisotropy in the mechanical response of polycrystalline aggregates,particularly those with the charac-teristic complex grain morphology of AM *** contribution c

关键词： Axial grain size grain size anisotropy Strain hardening anisotropy grain morphology Morphological texture Columnar grains Additive manufacturing

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Tailoring grain morphology in Ti-6Al-3Mo through heterogeneous nucleation in directed energy deposition

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Journal of Materials Science & Technology 2021年第29期88卷 132-142页

作者： Fengying Zhang Panpan Gao Hua Tan Yao Li Yongnan Chen Min Mei Adam T.Clare Lai-Chang Zhang School of Material Science and Engineering Chang’an UniversityXi’an710064China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China Advanced Component Engineering Laboratory Faculty of EngineeringUniversity of NottinghamNG72RDUnited Kingdom School of Engineering Edith Cowan University270 Joondalup DriveJoondalupPerthWA6027Australia

A common challenge in direct energy deposition(DED)is eliminating the anisotropy in mechanical performance associated with microstructure and the formation of coarse columnar *** this work,a heterogeneous nucleation mechanism was introduced into the melt pool,and,from this mechanism,an almost fully equiaxed grain morphology was obtained in the DED of Ti-6 Al-3 *** types of grain morphologies in DED Ti-6 Al-3 Mo,including full columnar grains,near-equiaxed grains and almost fully equiaxed grains were obtained from premixed and satellite powder blends from Ti,6 wt.%Al and 3 wt.%Mo,*** with the analysis of the interactions between powder particles and the melt pool in DED,the formation mechanism of the equiaxed grains caused by the incomplete melting of high melting point Mo particles was *** the prior-βgrains transformed from coarse columnar grains to fine-equiaxed grains,the strongfiber texture along the deposition direction was weakened,while the size of theα-laths in the prior-βgrains slightly decreased,and the selection ofα-variants was *** to the transformation of the prior-βgrains from coarse columnar grains to fine-equiaxed grains,the tensile strength of the deposited samples increased from 982 MPa to 1082 MPa,while the yield strength increased from 840 MPa to 922 MPa,and the elongation of the as-deposited alloy also increased from 9.0%to 9.8%,which confirmed that the presence of fine-equiaxed grains is beneficial to the strength and plasticity of the DED *** work further demonstrates the role that satelliting powders can play in terms of enhancing the columnar to equiaxed transition(CET)behavior associated with DED.

关键词： Direct energy deposition Titanium alloy grain morphology Microstructure Mechanical properties

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Mechanical and corrosion properties of biodegradable magnesium mini-tubes with different grain morphologies:Size and distribution

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Journal of Materials Science & Technology 2024年第16期183卷 165-174页

作者： Xiang Wang Chun Chen Bozun Miao Zilong Wang Hua Huang Shaokang Guan Guangyin Yuan National Engineering Research Center of Light Alloy Net Forming and Key State Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240 China School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450002China

Biodegradable magnesium(Mg)alloys have received much attention due to their biocompatibility and *** this study,to uncover the effects of grain morphologies,including grain size and distribution on mechanical and corrosion properties,biodegradable Mg-2.1Nd-0.2Zn-0.5Zr(wt.%)(denoted as JDBM)alloy mini-tubes for stent application with three typical microstructures were achieved success-fully by adjusting drawing *** with the bimodal structure exhibit the highest strengthductility balance attributed to the combined effects of fine grains and coarse grains,but show the fastest corrosion rate of about 1.00±0.136 mm/year mainly due to the formation of micro galvanic couples between coarse and fined *** with fine equiaxed grains show the lowest corrosion rate of about 0.17±0.059 mm/year,as well as uniform corrosion mode and mechanical properties of yield strength(YS)256±5.7 MPa,ultimate tensile strength(UTS)266±3.8 MPa,and elongation to failure(EL)13.5%±1.8%,attributed to the high-density grain *** with coarse equiaxed grains exhibit medium corrosion resistance and mechanical properties of about 175±4.8 MPa,221±4.0 MPa,and 21.53%±4.1%.Considering the mechanical and in vitro corrosion properties,biodegradable JDBM alloy implants are recommended to be composed of fine equiaxed grains,which can be used as microstructural targets for fabrication and processing.

关键词： Magnesium alloy grain morphology Corrosion Mechanical properties Mini-tubes

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Kernel position effects of grain morphological characteristics by X-ray micro-computed tomography (μCT)

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International Journal of Agricultural and Biological Engineering 2021年第2期14卷 159-166页

作者： Xuebo Yin Junfeng Hou Bo Ming Ying Zhang Xinyu Guo Shang Gao Keru Wang Peng Hou Shaokun Li Ruizhi Xie Institute of Crop Sciences Chinese Academy of Agricultural SciencesKey Laboratory of Crop Physiology and EcologyMinistry of Agriculture and Rural AffairsBeijing 100081China Institute of Maize and Featured Dryland Crops Zhejiang Academy of Agriculture SciencesJinhua 322100ZhejiangChina Beijing Key Laboratory of Digital Plant Beijing Research Center for Information Technology in AgricultureBeijing 100097China

grain size and shape are important factors for yield and *** difference in grain phenotypic characteristics in the same maize hybrid is related to its position in the *** study aimed to clarify the distribution characteristics of grain morphological characteristics in the ear and to provide guidance for research of grain phenotype and kernel position *** maize hybrids were used in the experiment,namely,Denghai 618(DH618),KX3564,and Xianyu 335(XY335),and the kernel number per row were 40,40,and 36,*** X-rayμCT was applied to obtain five kernel morphological indicators,including grain length,width,thickness,volume,surface *** sphericity,length-width ratio,specific surface area,and volume coefficient were further *** results showed that there were three types of maize ear morphological indicators trends:grain length,width,volume,and surface area were parabolic;thickness and sphericity were inverted parabolic;length-to-width ratio and specific surface area were *** volume coefficient of grain at different parts of the ear,namely the relation coefficient between grain volume and grain length,width,and thickness,was *** average value of the middle grains morphological indicators of the ear was taken to select kernels representing stable characteristics of the *** the range of 5%deviation from the morphological mean value of the middle grains of the ear,the grains in the middle part accounted for 26.39%of the total ear,about 10 grains extending from the 14th grain at the base of the ear to the *** the range of 10%deviation,the middle accounted for 47.22%,about 18 grains extending from the 12th grain at the base of the ear to the *** study found that grain morphological indicators were greatly different at different positions of the maize ear,and showed different change rules as extend from the base to the top of the ***,there were different grain volume coefficients

关键词： grain morphology X-rayμCT kernel position effects maize(Zea Mays L.)

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Microstructure Modification and Ductility Improvement for TaMoNbZrTiAl Refractory High Entropy Alloys via Increasing Ti Content

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Acta Metallurgica Sinica(English Letters) 2024年第7期37卷 1186-1200页

作者： Yujing Zhou Siyi Peng Yueling Guo Xiaoxiang Wu Changmeng Liu Zhiming Li School of Mechanical Engineering Beijing Institute of TechnologyBeijing100081China Shagang School of Iron and Steel Soochow UniversitySuzhou215137China School of Materials Science and Engineering Central South UniversityChangsha410083China

Here, the composition of TaMoNbZrTiAl refractory high entropy alloy (RHEA) is optimized by increasing Ti content to improve its mechanical property especially the ductility, through comparing two RHEAs with different Ti content. The RHEAs contain two body-centered-cubic (BCC) phases. The BCC phase in the dendritic region is rich in Ta, Mo and Nb, and the BCC phase in the interdendritic region is enriched in Zr, Ti and Al. The as-cast RHEA with a higher Ti content remains dendritic microstructures, and Ti is mainly enriched in the interdendritic region. After annealing treatment at 1300 ℃ for 48 h, the dendritic microstructures change into equiaxed-grain morphology, accompanied by needle-like micron precipitates at grain boundaries in the RHEA with higher Ti content. For the as-cast RHEAs, the fracture strain increases by ~ 6.6% and the uniform plastic strain increases by ~ 5.9% at the compression test due to the increase of Ti content. Our work offers a reference for the composition design of RHEAs and makes a preliminary exploration of the optimization of the microstructures and mechanical properties.

关键词： Refractory high entropy alloys Solidification grain morphology Microstructure Mechanical property

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Anisotropy of mechanical properties of 2297-T87 Al–Li alloy thick plates

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International Journal of Minerals,Metallurgy and Materials 2023年第11期30卷 2212-2223页

作者： Yuji Bai Zhixiu Wang Bo Jiang Mengqi Li Cong Zhu Xiaotong Gu Hai Li School of Materials Science and Engineering Changzhou UniversityChangzhou 213164China Jiangsu Key Laboratory of Material Surface Science and Technology Changzhou UniversityChangzhou 213164China

The tensile properties of 2297-T87 Al–Li alloy thick plates at different thickness position and in different direction were analyzed via tensile testing,optical microscopy(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM),energy dispersive spectrometry(EDS),and transmission electron microscopy(TEM).Results indicated that the ultimate tensile strength(UTS)and yield strength(YS)of the alloy decreased firstly and then increased from the 1/8T position to the 1/2T position,whereas elongation to failure(Ef)decreased gradually such that its value along the rolling direction(RD)was higher than those along the transverse direction(TD)at the same thickness *** the 1/8T position to the 3/8T position of the alloy,the UTS and YS along the TD were higher than those along the *** the 1/2T position of the alloy,the UTS,YS,and Ef along the RD were the highest,whereas those along the normal direction(ND)were the *** observations further revealed that the anisotropy of tensile properties was related to grain morphology,crystal texture,second-phase particles,and Li atom segregation.

关键词： 2297 alloy thick plate tensile properties anisotropy grain morphology second-phase particles

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Rice grains from Slightly Saline Field Exhibited Unchanged Starch Physicochemical Properties but Enhanced Nutritional Values

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Rice science 2024年第3期31卷 343-360,I0055-I0057页

作者： Supranee SANTANOO Wichian SANGWONGCHAI Maysaya THITISAKSAKUL Suphatta PHOTHISET Paweena PONGDONTRI Noppawan NOUNJAN Piyada THEERAKULPISUT Department of Biology Faculty of ScienceKhon Kaen UniversityKhon Kaen 40002Thailand Salt-Tolerant Rice Research Group Khon Kaen UniversityKhon Kaen 40002Thailand Biological Science Program Faculty of ScienceKhon Kaen UniversityKhon Kaen 40002Thailand Department of Biochemistry Faculty of ScienceKhon Kaen UniversityKhon Kaen 40002Thailand Department of Food Technology and Nutrition Faculty of Natural Resources and Agro-IndustryKasetsart UniversityChalermphrakiat Sakon Nakhon Province CampusSakon Nakhon 47000Thailand International College Khon Kaen UniversityKhon Kaen 40002Thailand

This study aims to investigate grain quality and nutritional values of rice(Pokkali,a salt-tolerant cultivar;RD73,a new cultivar improved from KDML105 introgressed with Saltol QTL from Pokkali,and KDML105,a moderately salt-susceptible cultivar)grown under non-saline(0.04–0.87 dS/m)and slightly saline(1.08–4.83 dS/m)field *** results revealed that salinity caused significant reduction in grain size but significant increments in reducing sugar and total protein contents in the ***,the amounts of starch in the grains of KDML105 and Pokkali rice genotypes were unaffected by the *** starch granule size distribution was also unaffected by ***,only starch from Pokkali was significantly diminished in amylose content,from 19.18%to 16.99%.Accordingly,parameters relating to starch gelatinization,retrogradation,and pasting properties of KDML105 and RD73 were unaffected by salinity;only Pokkali showed a significant increase in percentage of retrogradation along with a significant reduction in gelatinization *** the saline field,total phenolic content and antioxidant capacity in the grains of all rice cultivars tended to increase,particularly in *** average,essential element contents in grains from the saline-treated plants showed a 33%,32%,32%,22%,20%,11%,and 10%increase in total P,N,K,Mg,Zn,Fe,and Ca content,***,total Fe content exhibited the greatest percentage of increments in KDML105(187%).Taken together,cultivation of rice in the slightly saline field did not alter its eating and cooking qualities,while enhanced some nutritional properties such as proteins,minerals,and secondary metabolites like phenolic compounds.

关键词： antioxidant capacity elemental composition gelatinization grain morphology retrogradation rice salt stress starch granule

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Influence of thermal-decomposition temperatures on structures and properties of V2O5 as cathode materials for lithium ion battery

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Progress in Natural Science:Materials International 2015年第1期25卷 42-46页

作者： Yu Chen Cheng Chen Wei Chen Heng Liu Jianguo Zhu School of Aeronautics and Astronautics Sichuan University Chengdu University of Information and Technology Beijing Beiji Mechanical & Electric Industry Co. Ltd College of Materials Science and Engineering Sichuan University

Submicron spherical V2O5 particles with a uniform size and a lower crystallinity were successfully synthesized by a chemical precipitationthermal decomposition technique using the commercial V2O5 powders as starting material. The crystal structure and grain morphology of samples were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM), respectively. Electrochemical testing such as discharge–charge cycling(CD) and cyclic voltammetry(CV) were employed in evaluating their electrochemical properties as cathode materials for lithium ion battery. Results reveal that the crystallinity and crystalline size of V2O5 particles increased when the thermal-decomposition temperature increased from 400 ℃ to 500 ℃, and their adhesiveness was also synchronously increased. This indicate that the thermaldecomposition temperature palyed a significant influence on electrochemical properties of V2O5 cathodes. The V2O5 sample obtained at 400 ℃ delivered not only a high initial discharge capacity of 330 m A h g-1and also the good cycle stability during 50 cycles due to its higher values ofα in crystal structure and better dispersity in grain morphology.

关键词： V2O5 Thermal decomposition Crystal structure grain morphology Electrochemical properties

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Comparison of irradiation-induced void formations in tungsten with equiaxed and columnar structures

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Tungsten 2024年第4期6卷 794-805页

作者： Liu Xi Jia-Jun Zhao Ji-Jun Zhao Yuan-Yuan Wang Key Laboratory of Materials Modification by Laser Ion and Electron Beams(Ministry of Education)Dalian University of TechnologyDalian116024China

Tungsten(W)has been received much attention,since it is regarded as one of the most promising plasma facing materials for fusion *** are two typical morphologies of unirradiated polycrystalline W,which have the equiaxed and columnar grains,***,the role of arrangement of grain boundary(GB)in absorbing irradiation-generated point defects is still waiting to be *** current investigation,irradiation-induced void formations in W with equiaxed and columnar microstructures are predicted,respectively,using the developed phase-field *** significant kinetic behavior,such as the generation and annihilation of point defects and the interaction between point defects and GB,is reasonably *** density,size and porosity of void formed in these two microstructures are examined and analyzed according to the effects of GB ratio,temperature and damage *** analytical results show that higher GB ratio can effectively reduce void porosity,and the columnar-grained structure has better irradiation resistance than that of the equiaxed one in the case of small grain *** importantly,the predicted void sizes changed with temperature and damage rate agree well with the experimentally measured *** work has a more beneficial contribution to the microstructural improvement of International Thermonuclear Experimental Reactor-grade W.

关键词： Tungsten Phase-field Irradiation-induced void grain morphology

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Microstructure and mechanical properties of TA15/TC11 graded structural material by wire arc additive manufacturing process

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Transactions of Nonferrous Metals Society of China 2021年第8期31卷 2323-2335页

作者： He WANG Shu-yuan MA Jia-chen WANG Tao LU Chang-meng LIU School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China

A graded structural material(GSM)with a material transition from TA15 to TC11 was fabricated by wire arc additive manufacturing(WAAM)*** grain morphology,chemical composition,microstructure and mechanical properties of the as-deposited GSM were all characterized to investigate their variations along the deposition *** results indicate that from TA15 to TC11,the grain size decreases and a transition from columnar grains to equiaxed grains *** content of alloy element alters greatly within a short distance,and the width of the mutation zone is 800μ*** TA15 and TC11 regions exhibit basketweave microstructure withα-phase andβ-***,during the transition from TA15 to TC11,theα-lath becomes fine,which leads to an increase in *** tensile test shows that the bonding strength at the interface is higher than the longitudinal strength of TA15,and the lateral elongation at the interface is higher than that of TA15 and TC11.

关键词： wire arc additive manufacturing graded structural material grain morphology microstructure mechanical properties

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