检索结果-南通市图书馆

Journal of Magnesium and Alloys 2024年第5期12卷 1841-1853页

作者： M.Lv H.L.Ge Q.Q.Jin X.H.Shao Y.T.Zhou b.zhang X.L.Ma Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences School of Materials Science and Engineering University of Science and Technology of China Materials Science and Engineering Research Center Guangxi University of Science and Technology

In-situ electron irradiation and aging are applied to introduce high-density precipitates in an Mg-10Gd-3Y-1Zn-0.5Zr(GWZ1031K, wt.%)alloy to improve the hardness. The results show that the hardness of the Mg alloy after irradiation for 10 h and aging for 9 h at 250 ℃ is 1.64 GPa, which is approximately 64% higher than that of the samples before being treated. It is mainly attributed to γ' precipitates on the basal plane after irradiation and the high-density nanoscale β' precipitates on the prismatic plane after aging, which should be closely related to the irradiation-induced homogenous clusters. The latter plays a key role in precipitation hardening. This result paves a way to improve the mechanical properties of metallic materials by tailoring the precipitation through irradiation and aging.

关键词： Mg alloy Electron beam irradiation Hardening Precipitates In-situ TEM

Enumerating Pattern-avoiding Fishburn Permutations Subject to Seven Statistics

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Mathematical Research with Applications 2024年第4期 427-436页

作者： Yujie DU Philip b.zhang College of Mathematical Science Tianjin Normal University

Fishburn permutations are in bijection with several important combinatorial structures including interval orders. In this paper, we use the method of generating trees to enumerate two classes of pattern-avoiding Fishburn permutations subject to 7 classical statistics simultaneously. The classes of our interest are(321,312)-avoiding and(321,4123)-avoiding Fishburn permutations. The statistics of our interest are ascents, descents, inversions, right-to-left maxima, right-to-left minima, left-to-right maxima and left-to-right minima. Our results generalize a result by Egge.

关键词：

Stabilizing nanograined Fe-Cr alloy by Si-assisted grain boundary segregation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2023年第3期134卷 223-233页

作者： X.F.Xu X.Y.Li b.zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China

Intentional solute segregation at grain boundary(Gb)can effectively stabilize the nanograined alloys by reducing the excess energy and mobility of Gb,but it usually works for binary alloys with sufficient Gb segregation tendency.Here,we found that the segregation of Cr can be enhanced in a nanostruc-tured Fe-8Cr alloy with insufficient Gb segregation tendency through the interaction of another solute Si(1.0 wt.%).After surface mechanical grinding treatment and subsequent annealing,the nanograined Fe-8Cr-1Si is more thermally stable than the nanograined Fe-8Cr,which is mainly attributed to the Si-enhanced Cr segregation as observed by Super-X energy-dispersive X-ray spectroscopy(EDS)mapping system.With the grain refinement to nanoscale,the thermal stability is further improved due to the in-crease of Cr content at Gbs and the precipitates formed at appropriate high temperatures.The present finding provides guidance for the development of advanced nanostructured ternary alloys.

关键词： Segregation Grain boundary Fe-Cr-Si alloy Nanocrystalline Thermal stability

Improving the strength and SCC resistance of an Al-5Mg-3Zn alloy with low-angle grain boundary structure

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2023年第30期161卷 63-73页

作者： Z.C.Tang W.Xu D.Y.Zhao b.zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

The strength of traditional Al-Mg alloys is relatively low because it mainly relies on solid solution strengthening.Adding a third component to form precipitation can improve their strength,but it usually leads to high-stress corrosion cracking(SCC)sensitivity due to the formation of high-density precipitates at grain boundaries(Gbs).So far,it is still challenging to improve the strength of Al-Mg alloys without re-ducing SCC resistance.Herein,a nanostructured Al-5Mg-3 Zn alloy with a good yield strength of 336 MPa and good elongation was successfully produced.by dynamic plastic deformation and appropriate anneal-ing treatment,near-equiaxed nanograins were introduced in the nanostructured Al-5Mg-3 Zn alloy with a high proportion(71%)of the low-angle grain boundary.TEM statistical investigations show that the pre-cipitation of active T’phase at Gbs has been greatly suppressed in the nanostructured Al-5Mg-3 Zn alloy at sensitized conditions,and the area fraction of Gb precipitates is reduced from 72%to 21%,which sig-nificantly decreases the SCC susceptibility.This study provides guidance for developing advanced Al-Mg alloy with high SCC resistance.

关键词： Al-5Mg-3 Zn alloy Stress corrosion cracking Low angle grain boundary Nanostructured Dynamic plastic deformation

Enhanced oxidation resistance of Ce by addition of Ga and nanocrystallization

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2023年第16期147卷 26-36页

作者： T.S.Liang Y.F.Jiang H.Y.Li W.Wang Q.zhang b.zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China The 404 Company Limited China National Nuclear CorporationLanzhou 732850China State Key Laboratory of Material Processing and Die&Mould Technology School of Material Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Ce is prone to catastrophic oxidation at room temperature and its oxidation resistance is difficult to be improved by alloying.Herein,we found that the oxidation resistance of active metal Ce can be significantly improved by the addition of 20 at.%Ga.Focused ion beam lift-out technique and scanning transmission electron microscopy analysis disclosed that a discontinuous Ga-rich layer was generated beneath the oxide layer in the coarse-grained Ce-Ga alloy.The Ga-rich layer formed by selective oxidation of Ce acts as a diffusion barrier for Ce outward diffusion and ceases the O/M interfacial reaction when a critical concentration of Ga(75 at.%)is reached.After nanocrystallization,uniform distribution of Ga was achieved.After oxidation,a relatively continuous Ga-rich layer was formed which further enhanced the oxidation resistance.The introduction of noble elements combining with nanocrystallization may provide a novel strategy for the protection of metals with high activity and poor oxidation resistance.

关键词： Ce-Ga alloy Oxidation resistance Diffusion barrier Nanocrystallization

Formation of β' phase in LPSO structures in an Mg88Co5Y7 alloy

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2022年第1期10卷 175-182页

作者： Q.Q.Jin X.H.Shao Y.T.Zhou b.zhang S.J.Zheng X.L.Ma Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua Road110016 ShenyangChina Materials Science and Engineering Research Center Guangxi University of Science and TechnologyLiuzhou 545006China School of Materials Science and Engineering Research Institute for Energy Equipment MaterialsHebei University of TechnologyTianjin 300130China

Formation of β’ phase in long-period stacking ordered(LPSO) structures in an Mg;Co;Y;(at.%) alloy after aging at 200 °C for 24 h or electron beam(Eb) irradiation has been studied by high-angle annular dark-field scanning transmission electron microscopy(HAADFSTEM). β’ phase was precipitated only in the Mg matrix but not in LPSO structures after aging at 200 °C for 24 h. LPSO structure containing stacking defects transforms into the β’-long phase during Eb irradiation, which plays a key role in accelerating solute atoms’ diffusion. New complex β’(LPSO) structures formed in the alloy after Eb irradiation, such as β’(12 H) structure with an orthorhombic lattice(Mg;Y, Cmcm,a = 2 _(a0)= 0.642 nm, b=4√3_(a0), c = 6 _(c0)= 3.12 nm).

关键词： Magnesium alloys Long-period stacking ordered(LPSO)structure HAADF-STEM β’phase

A review——Pitting corrosion initiation investigated by TEM

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2019年第7期35卷 1455-1465页

作者： b.zhang X.L.Ma Shenyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences

Passive metals have superior resistance to general corrosion but are susceptible to pitting attack in certain aggressive media, leading to material failure with pronounced adverse economic and safety consequences. Over the past decades, the mechanism of pitting corrosion has attracted corrosion community striving to study. However, the mechanism at the pitting initiation stage is still controversy, due to the difficulty encountered in obtaining precise experimental information with enough spatial resolution.Tracking the accurate sites where initial dissolution occurs as well as the propagation of the dissolution by means of multi-scale characterization is key to deciphering the link between microstructure and corrosion at the atomic scale and clarifying the pitting initiation mechanism. Here, we review our recent progresses in this issue by summarizing the results in three representative materials of 316F, and Super 304H stainless steel as well as 2024-Al alloy, using in situ ex-environmental TEM technique.

关键词： Pitting initiation Dissolution TEM Inclusion Second phase

The role of melt cooling rate on the interface between 18R and Mg matrix in Mg_(97)Zn_(1)Y_(2) alloys

在线全文

学校读者我要写书评

暂无评论

Journal of Magnesium and Alloys 2023年第8期11卷 2883-2890页

作者： Q.Q.Jin X.H.Shao J.M.Li Z.Z.Peng M.Lv b.zhang Y.M.Li X.L.Ma Materials Science and Engineering Research Center Guangxi University of Science and TechnologyLiuzhou 545006China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Hebei University of Science and TechnologyShijiazhuangHebei 050018China

The role of melt cooling rate on the interface morphology and dislocation configuration between 18R long-period stacking ordered(LPSO)structure and Mg matrix in Mg_(97)Zn_(1)Y_(2)(at.%)alloys was investigated by atomic-scale HAADF-STEM imaging.The 18R/Mg interface is step-like both in the near-equilibrium alloy and non-equilibrium alloy.Lower cooling rate makes the step size more regular and larger.Only 54R structure can be observed at the interface in the near-equilibrium alloy,and the dislocations are highly ordered.54R and 54R′structure sandwiched by b1 and b2+b3 dislocation arrays,and new dislocation configuration can be detected at the interface in the non-equilibrium alloy,but the dislocations are less ordered.18R/Mg interface containing 54R or 54R′in equilibrium width,parallel to the(010)plane,should be most stable based on elastic calculation.The segregation of solute atoms and its strong interaction with dislocations dominate the LPSO/Mg interface via diffusion-displacive transformation.

关键词： Magnesium alloys Long-period stacking ordered phases Dislocations Interface structure

THE HOT DEFORMATION bEHAVIOR AND DYNAMIC RECRYSTALLIZATION MODEL OF 35CrMo STEEL

在线全文

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2003年第3期16卷 183-191页

作者： b.zhang H.b.zhang X.Y.Ruan Y.zhang Department of Plasticity Technology Shanghai Jiao Tong University Shanghai 200030 ChinaDepartment of Materials Science and Engineering Shanghai Institute of Technology Shanghai 200053ChinaDepartment of Plasticity Technology Shanghai Jiao Tong UniversityShanghai 200030ChinaState Key Laboratory for Advanced Metals & MaterialsUniversity of Science and Technology BeliingBeijing 100083 China

The isothermal single-stage compression of 35CrMo structural steel has been carried out by using Gleeble 1500 simulator at the temperature range of 950℃ to 1150℃ and strain rate range of 0.01s-1 to 10s-1. The effect of hot deformation parameters, such as strain rate, deformed temperature and initial grain size on the flow stress behavior was investigated. The activation energy of tested alloy was calculated, which is 378.16kJ/mol; The relationships between the peak stress (σp), the peak stain (εp), the critical strain (εc) and Z parameter were established. The micro structure evolution shows the pre-existing austenite grain boundaries constitute the principal nucleation sites for dynamic recrystallization (DRX), and the initial austenite grain size affects the grain size of DRX slightly. The kinetic mathematical model of DRX of 35CrMo is: XDRX=1-exp(-3.23-2.28) and Ddyn = 2.252× 10Z-0.22.

关键词： dynamic recrystallization deformation activation energy stress/strain curve grain size

Guided Waves in the Multilayered One-Dimensional Hexagonal Quasi-crystal Plates

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2021年第1期34卷 91-103页

作者： b.zhang J.G.Yu X.M.zhang X.H.Wang School of Mechanical and Power Engineering Henan Polytechnic UniversityJiaozuo454003China

Guided waves in the multilayered one-dimensional quasi-crystal plates are,respectively,investigated in the context of the bak and elasto-hydrodynamic models.Dispersion curves and phonon and phason displacements are calculated using the Legendre polynomial method.Wave characteristics in the context of these two models are analyzed in detail.Results show that the phonon-phason coupling effects on the first two layers are the same at low frequencies;but,they are more significant on the first layer than those on the second layer at high frequencies.These obtained results lay the theoretical basis of guided-wave nondestructive test on multilayered quasi-crystal plates.

关键词： Multilayered structures Quasi-crystal plate Guided wave Phonon-phason coupling effect