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In vitro and in vivo studies on pure Mg, Mg-1Ca and Mg-2Sr alloys processed by equal channel angular pressing

Nano Materials Science 2020年第1期2卷 96-108页

作者： Wenting Li Yunong Shen Jie Shen Danni Shen Xiao Liu Yufeng Zheng Kelvin W.K.Yeung Shaokang Guan Olga B.Kulyasova R.Z.Valiev Department of Materials Science and Engineering College of EngineeringPeking UniversityBeijing100871China College of Materials Science and Engineering University of Science and Technology BeijingBeijing100083China Department of Orthopaedics and Traumatology The University of Hong KongPokfulamHong KongChina School of Materials Science and Engineering Zhengzhou UniversityZhengzhou450001China Ufa State Aviation Technical University 12 Karl Marx StreetUfa450008Russia

In the present work,the biomedical as-cast pure Mg,Mg–1 Ca and Mg–2 Sr alloys were processed with equal channel angular pressing(ECAP)technique to develop ultrafine microstructure within the materials,and their microstructures,mechanical properties,degradation behavior,cytocompatibility in vitro and biocompatibility in vivo were studied comprehensively.Finer-gained microstructures and improved mechanical properties of these three materials after ECAP were confirmed compared to their as-cast counterparts.Moreover,after ECAP the degradation rate of pure Mg was increased while that of Mg–1 Ca or Mg–2 Sr alloys decreased compared to the ascast counterparts.Additionally,good in vitro cytocompatibility and in vivo biocompatibility of these three materials were revealed by cell cultural tests using osteoblastic MC3 T3-E1 and human mesenchymal stem cells(h MSC)and in vivo animal tests at the lateral epicondyle of SD-rats’femur.This study offers an alternative powerful avenue to achieve good comprehensive properties of magnesium-based biodegradable metals.It might also help to extend the applied range of magnesium-based biodegradable metals in orthopedic field.

关键词： Magnesium alloys Equal channel angular pressing Mechanical property Degradation behavior Biocompatibility

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Uncertainty-quantified parametrically homogenized constitutive models (UQ-PHCMs) for dual-phase α/β titanium alloys

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npj Computational Materials 2020年第1期6卷 677-696页

作者： Shravan Kotha Deniz Ozturk Somnath Ghosh Departments of Civil Mechanical and Materials Science&EngineeringJohns Hopkins University3400 N.Charles StreetBaltimoreMD 21218USA

This paper develops an uncertainty-quantified parametrically homogenized constitutive model(UQ-PHCM)for dual-phase α/βtitanium alloys such as Ti6242S.Their microstructures are characterized by primaryα-grains consisting of hcp crystals and transformedβ-grains consisting of alternating laths ofα(hcp)and β(bcc)phases.The PHCMs bridge length-scales through explicit microstructural representation in structure-scale constitutive models.The forms of equations are chosen to reflect fundamental deformation characteristics such as anisotropy,length-scale dependent flow stresses,tension-compression asymmetry,strain-rate dependency,and cyclic hardening under reversed loading conditions.Constitutive coefficients are functions of representative aggregated microstructural parameters or RAMPs that represent distributions of crystallographic orientation and morphology.

关键词： alloys deformation constitutive

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Linking electronic structure calculations to generalized stacking fault energies in multicomponent alloys

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npj Computational Materials 2020年第1期6卷 989-997页

作者： Anirudh Raju Natarajan Anton Van der Ven Materials Department University of CaliforniaSanta BarbaraCA 93106USA

The generalized stacking fault energy is a key ingredient to mesoscale models of dislocations.Here we develop an approach to quantify the dependence of generalized stacking fault energies on the degree of chemical disorder in multicomponent alloys.We introduce the notion of a“configurationally-resolved planar fault”(CRPF)energy and extend the cluster expansion method from alloy theory to express the CRPF as a function of chemical occupation variables of sites surrounding the fault.We apply the approach to explore the composition and temperature dependence of the unstable stacking fault energy(USF)in binary Mo–Nb alloys.First-principles calculations are used to parameterize a formation energy and CRPF cluster expansion.Monte Carlo simulations show that the distribution of USF energies is significantly affected by chemical composition and temperature.The formalism is broadly applicable to arbitrary crystal structures and alloy chemistries and will enable the development of rigorous models for deformation mechanisms in high-entropy alloys.

关键词： alloy alloys fault

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Coupling physics in machine learning to predict properties of high-temperatures alloys

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npj Computational Materials 2020年第1期6卷 477-483页

作者： Jian Peng Yukinori Yamamoto Jeffrey A.Hawk Edgar Lara-Curzio Dongwon Shin Materials Science and Technology Division Oak Ridge National LaboratoryOak RidgeTN 37831USA Materials Performance Division National Energy Technology LaboratoryAlbanyOR 97321-2198USA

High-temperature alloy design requires a concurrent consideration of multiple mechanisms at different length scales.We propose a workflow that couples highly relevant physics into machine learning(ML)to predict properties of complex high-temperature alloys with an example of the 9–12 wt% Cr steels yield strength.We have incorporated synthetic alloy features that capture microstructure and phase transformations into the dataset.Identified high impact features that affect yield strength of 9Cr from correlation analysis agree well with the generally accepted strengthening mechanism.

关键词： alloys alloy strength

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Microstructure and mechanical properties of Fe_xCoCrNiMn high-entropy alloys

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Journal of Materials Science & Technology 2019年第10期35卷 2331-2335页

作者： Tao Zhang Lijun Xin Fufa Wu Rongda Zhao Jun Xiang Minghua Chen Songshanjiang Yongjiang Huang Shunhua Chen School of Materials Science and Engineering Liaoning University of TechnologyJinzhou121001China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin150001China School of Mechanical Engineering Hefei University of TechnologyHefei230009China

The microstructure and tensile properties of FexCo Cr Ni Mn high-entropy alloys(HEAs) were investigated.It was found that the FexCo Cr Ni Mn HEA has a single face-centered cubic(fcc) structure in a wide range of Fe content. Further increasing the Fe content endowed the FexCo Cr Ni Mn alloys with an fcc/bodycentered cubic(bcc) dual-phase structure. The yield strength of the FexCo Cr Ni Mn HEAs slightly decreased with the increase of Fe content. An excellent combination of strength and ductility was achieved in the FexCo Cr Ni Mn HEA with higher Fe content, which can be attributed to the outstanding deformation coordination capability of the fcc/bcc dual phase structure.

关键词： High-entropy alloys Microstructure Mechanical properties Strength Ductility

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Tunable chemical complexity to control atomic diffusion in alloys

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npj Computational Materials 2020年第1期6卷 1360-1367页

作者： Yuri Osetsky Alexander V.Barashev Laurent K.Béland Zhongwen Yao Keyvan Ferasat Yanwen Zhang Materials Science and Technology Division Oak Ridge National LaboratoryOak RidgeTN 37831USA Department of Nuclear Engineering and Radiological Sciences University of MichiganAnn ArborMI 48109USA Department of Mechanical and Materials Engineering Queen’s UniversityKingstonON K7L 3N6Canada Department of Materials Science and Engineering University of TennesseeKnoxvilleTN 37996USA

In this paper we report a new fundamental understanding of chemically-biased diffusion in Ni–Fe random alloys that is tuned/controlled by the intrinsic quantifiable chemical complexity.Development of radiation-tolerant alloys has been a long-standing challenge.Here we show how intrinsic chemical complexity can be utilized to guide the atomic diffusion and suppress radiation damage.The influence of chemical complexity is shown by the example of interstitial atom(IA)diffusion that is the most important defect in radiation effects.We useμs-scale molecular dynamics to reveal sluggish diffusion and percolation of IAs in concentrated Ni–Fe alloys.We develop a mean field diffusion model to take into account the effect of migrating defect energy properties on diffusion percolation,which is verified by a new kinetic Monte Carlo approach addressing detailed processes.We demonstrate that the local variations in the ground state energy of IA configurations in alloys,reflecting the chemical difference between alloying components,drives the percolation effects for atomic diffusion.Percolation,chemically-biased and sluggish diffusion are phenomena that are directly related to the chemical complexity intrinsically to multicomponent alloys.

关键词： alloys alloying diffusion

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Cluster-formula-embedded machine learning for design of multicomponent β-Ti alloys with low Young’s modulus

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npj Computational Materials 2020年第1期6卷 824-834页

作者： Fei Yang Zhen Li Qing Wang Beibei Jiang Biaojie Yan Pengcheng Zhang Wei Xu Chuang Dong Peter K.Liaw Key Laboratory of Materials Modification by Laser Ion and Electron Beams(Ministry of Education)School of Materials Science and EngineeringDalian University of TechnologyDalian116024 LiaoningChina School of Mechanical Engineering Dalian University of TechnologyDalian116024 LiaoningChina Analysis and Test Center Guangdong University of TechnologyGuangzhou510006 GuangdongChina Institute of Materials China Academy of Engineering PhysicsJiangyou621908 SichuanChina State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang110819 LiaoningChina Department of Materials Science and Engineering The University of TennesseeKnoxville37996 TNUSA

The present work formulated a materials design approach,a cluster-formula-embedded machine learning(ML)model,to search for body-centered-cubic(BCC)β-Ti alloys with low Young’s modulus(E)in the Ti–Mo–Nb–Zr–Sn–Ta system.The characteristic parameters,including the Mo equivalence and the cluster-formula approach,are implemented into the ML to ensure the accuracy of prediction,in which the former parameter represents the BCC-βstructural stability,and the latter reflects the interactions among elements expressed with a composition formula.Both auxiliary gradient-boosting regression tree and genetic algorithm methods were adopted to deal with the optimization problem in the ML model.

关键词： alloys modulus formula

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Ab initio modeling of the energy landscape for screw dislocations in body-centered cubic high-entropy alloys

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npj Computational Materials 2020年第1期6卷 754-764页

作者： Sheng Yin Jun Ding Mark Asta Robert O.Ritchie Department of Materials Science and Engineering University of CaliforniaBerkeleyCA 94720USA Materials Sciences Division Lawrence Berkeley National LaboratoryBerkeleyCA 94720USA

In traditional body-centered cubic(bcc)metals,the core properties of screw dislocations play a critical role in plastic deformation at low temperatures.Recently,much attention has been focused on refractory high-entropy alloys(RHEAs),which also possess bcc crystal structures.However,unlike face-centered cubic high-entropy alloys(HEAs),there have been far fewer investigations into bcc HEAs,specifically on the possible effects of chemical short-range order(SRO)in these multiple principal element alloys on dislocation mobility.Here,using density functional theory,we investigate the distribution of dislocation core properties in MoNbTaW RHEAs alloys,and how they are influenced by SRO.The average values of the core energies in the RHEA are found to be larger than those in the corresponding pure constituent bcc metals,and are relatively insensitive to the degree of SRO.However,the presence of SRO is shown to have a large effect on narrowing the distribution of dislocation core energies and decreasing the spatial heterogeneity of dislocation core energies in the RHEA.It is argued that the consequences of the mechanical behavior of HEAs is a change in the energy landscape of the dislocations,which would likely heterogeneously inhibit their motion.

关键词： alloys deformation cubic

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Incipient plasticity and activation volume of dislocation nucleation for TiZrNbTaMo high-entropy alloys characterized by nanoindentation

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Journal of Materials Science & Technology 2019年第5期35卷 812-816页

作者： Shao-Ping Wang Jian Xu Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences 72 Wenhua Road Shenyang 110016 China University of Chinese Academy of Sciences 19(A) Yuquan Road Beijing 100049 China

With instrumented nanoindentation, incipient plasticity of two as-cast BCC TiZrNbTa and TiZrNbTaMo high-entropy alloys(HEAs) are investigated in terms of pop-in events during loading, to characterize the dislocation behavior in these solid-solution alloys. It is shown that the maximum shear stress (max)required for dislocation nucleation is determined to be 1/16-1/12 and 1/18-1/14 of shear modulus for the TiZrNbTa and TiZrNbTaMo HEAs, respectively, which is nearly comparative to the theoretical shear stress of these alloys. The activation volumes of dislocation nucleation the TiZrNbTa and TiZrNbTaMo HEAs are determined to be 1.2 b^3 for and 1.3 b^3, respectively, which is substantially irrespective of alloying with Mo. Furthermore, activation volumes of these two HEAs are on the order of cubic burger’s vector and only one-third of the value for TiZrHfNb HEA, suggesting that a heterogeneous nucleation of dislocation took place in a way of direct atom-vacancy exchange, rather than of the cooperative motion of several atoms. These findings reveal the unique feature in deformation of BCC solid-solution complex alloys.

关键词： High-entropy alloys Nanoindentation Refractory metals BCC phase Incipient plasticity

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Fatigue crack initiation of magnesium alloys under elastic stress amplitudes:A review

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Frontiers of Mechanical Engineering 2019年第1期14卷 113-127页

作者： B.J.WANG D.K.XU S.D.WANG E.H.HAN School of Environmental and Chemical Engineering Shenyang Ligong UniversityShenyang 110159China CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The most advantageous property of magnesium(Mg)alloys is their density,which is lower compared with traditional metallic materials.Mg alloys,considered the lightest metallic structural material among others,have great potential for applications as secondary load components in the transportation and aerospace industries.The fatigue evaluation of Mg alloys under elastic stress amplitudes is very important in ensuring their service safety and reliability.Given their hexagonal close packed structure,the fatigue crack initiation of Mg and its alloys is closely related to the deformation mechanisms of twiuning and basal slips.However,for Mg alloys with shrinkage porosities and inclusions,fatigue cracks will preferentially initiate at these defects,remarkably reducing the fatigue lifetime.In this paper,some fundamental aspects about the fatigue crack initiation mechanisms of Mg alloys are reviewed,in cluding the 3 followings:1)Fatigue crack initiation of as-cast Mg alloys,2)influence of microstructure on fatigue crack initiation of wrought Mg alloys,and 3)the effect of heat treatment on fatigue initiation mechanisms.Moreover,some unresolved issues and future target on the fatigue crack initiation mechanism of Mg alloys are also described.

关键词： Mg alloys fatigue behavior microstructure crack initiation deformation mechanism

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