This study investigated the influence of graded Zn content on the evolution of precipitated and iron-rich phases and grain struc-ture of the alloys,designed and developed the Al–8.0Zn–1.5Mg–1.5Cu–0.2Fe(wt%)alloy w...This study investigated the influence of graded Zn content on the evolution of precipitated and iron-rich phases and grain struc-ture of the alloys,designed and developed the Al–8.0Zn–1.5Mg–1.5Cu–0.2Fe(wt%)alloy with high strength and formability.With the increase of Zn content,forming the coupling distribution of multiscale precipitates and iron-rich phases with a reasonable matching ratio and dispersion distribution characteristics is easy.This phenomenon induces the formation of cell-like structures with alternate distribu-tion of coarse and fine grains,and the average plasticity–strain ratio(characterizing the formability)of the pre-aged alloy with a high strength is up to 0.708.Results reveal the evolution and influence mechanisms of multiscale second-phase particles and the corresponding high formability mechanism of the alloys.The developed coupling control process exhibits considerable potential,revealing remarkable improvements in the room temperature formability of high-strength Al–Zn–Mg–Cu alloys.展开更多
通过显微组织观察、织构分析和拉伸测试等手段研究挤压比对双相Mg-8Li-6Zn-2Gd合金显微组织、织构和力学性能的影响。结果表明:均匀化态Mg-8Li-6Zn-2Gd合金中含有α-Mg、β-Li、Mg Li Zn、I相和W相。经热挤压后,共晶I相被碾碎成细小颗粒...通过显微组织观察、织构分析和拉伸测试等手段研究挤压比对双相Mg-8Li-6Zn-2Gd合金显微组织、织构和力学性能的影响。结果表明:均匀化态Mg-8Li-6Zn-2Gd合金中含有α-Mg、β-Li、Mg Li Zn、I相和W相。经热挤压后,共晶I相被碾碎成细小颗粒状,而W相保持原有块状形状。合金中α-Mg基体和β-Li基体在热挤压过程中均发生了动态再结晶(DRX),且晶粒随着挤压比的增加逐渐细化。经热挤压后,α-Mg基体的基面织构弱化和柱面织构增强是由于非基面滑移的激活;β-Li基体中形成明显的α和γ纤维织构主要与动态回复与动态再结晶相关。热挤压同时提升Mg-8Li-6Zn-2Gd合金的抗拉强度和伸长率,并在挤压比为16:1时获得最佳的综合力学性能。展开更多
In the current study,a homogenous ultra-fine grained microstructure with average grain size of 1.0μm is achieved in the Mg-Zn-Ca-Mn alloy through the reduplicative equal channel angular pressing(ECAP)at 300℃,and the...In the current study,a homogenous ultra-fine grained microstructure with average grain size of 1.0μm is achieved in the Mg-Zn-Ca-Mn alloy through the reduplicative equal channel angular pressing(ECAP)at 300℃,and the mechanical properties are remarkably improved,with room-temperature yield strength of 269.6 MPa and elongation of 22.7%.The twinning deformation results in a discontinuous recrystallization behavior in the initial stage of ECAP.With further deformation,the continuously dynamic recrystallization contributes to an obvious grain refinement effect.The activation of non-basal slip system leads to the formation of a unique basal texture,which is related to the elevated ECAP temperature and the decreased grain size.Both grain refinement and texture modification derived from ECAP process result in the increase of yield strength,while the cracked secondary phase particles are beneficial to the enhanced ductility,through reducing the stress concentration and hindering premature failure.展开更多
In this study,the effects of Al addition on the corrosion behavior of pure Mg with controlled impurity contents were systematically analyzed according to the processing history.The results revealed that the corrosion ...In this study,the effects of Al addition on the corrosion behavior of pure Mg with controlled impurity contents were systematically analyzed according to the processing history.The results revealed that the corrosion behavior of high-purity Mg-Al alloys is strongly related to changes in the microstructure,including theβphase and Al-Mn or Al-Fe phases,and the protectiveness of the surface film according to the Al content and processing history.In the as-cast alloys,the corrosion rate increased due to the increase ofβphase as the Al content increased,but in the as-extruded alloys,the corrosion rate,which was high due to intermetallic compounds caused by impurities in the low Al alloy,decreased as the Al content increased,and then increased again.This is due to the combined effect of the increase of theβphase and decrease of the impurity effect,and the increase of the dissolved Al content.The results suggest that it is necessary to analyze the effect of alloying elements on the corrosion behavior of pure Mg with information concerning the impurity content and processing history.展开更多
Magnesium alloys with a long-period stacking ordered(LPSO)structure usually possess excellent static strength,but their fatigue behaviors are poorly understood.This work presents the effect of the LPSO structure on th...Magnesium alloys with a long-period stacking ordered(LPSO)structure usually possess excellent static strength,but their fatigue behaviors are poorly understood.This work presents the effect of the LPSO structure on the crack behaviors of Mg alloys in a very high cycle fatigue(VHCF)regime.The LPSO lamellas lead to a facet-like cracking process along the basal planes at the crack initiation site and strongly prohibit the early crack propagation by deflecting the growth direction.The stress intensity factor at the periphery of the faceted area is much higher than the conventional LPSO-free Mg alloys,contributing higher fatigue crack propagation threshold of LPSO-containing Mg alloys.Microstructure observation at the facets reveals a layer of ultrafine grains at the fracture surface due to the cyclic contact of the crack surface,which supports the numerous cyclic pressing model describing the VHCF crack initiation behavior.展开更多
1 Introduction As the lightest metal with the unique properties of energy production and storage,lithium is regarded as the new century energy metal.Lithium and its compounds were widely used in various industrial fie...1 Introduction As the lightest metal with the unique properties of energy production and storage,lithium is regarded as the new century energy metal.Lithium and its compounds were widely used in various industrial fields,especially in展开更多
High pressure solidification rules of Al-Mg alloy needs to be discussed further for its wide range of application. Microstructures and phases of Al-25wt% Mg alloy solidified at 4 GPa were studied by optical microscope...High pressure solidification rules of Al-Mg alloy needs to be discussed further for its wide range of application. Microstructures and phases of Al-25wt% Mg alloy solidified at 4 GPa were studied by optical microscope,X-ray diffractmeter,energy dispersive X-ray spectroscopy and transmission electron microscopy( TEM). The microstructure evolution mechanism of Al-25Mg alloy under high pressure was analyzed. The result shows that the alloy consists of α-Al phase and Al 3 Mg 2 phase under normal pressure. However,only Al 12 Mg 17 phase forms without Al 3 Mg 2 phase at 4 GPa. In addition,Mg concentration in α-Al phase increases and that of the lattice constant also increases. The α-Al dendrite presents the broken arms under normal pressure, after high pressure solidification,the morphology of the dendrite tends to integrate and the size of the dendrite arms展开更多
The non-equilibrium microstructure and a new metastable phase of Al-9.6wt%Mg alloy solidified at 6 GPa were studied by optical microscope,differential scanning calorimetry,X-ray diffraction and transmission electron m...The non-equilibrium microstructure and a new metastable phase of Al-9.6wt%Mg alloy solidified at 6 GPa were studied by optical microscope,differential scanning calorimetry,X-ray diffraction and transmission electron microscope.The results showed that dendrite microstructure was refined,and the solid solubility of Mg in α-Al phase increased greatly.Correspondingly,the lattice parameter of α-Al phase increased.Al3Mg2 phases disappeared under high pressure solidification.In particular,a metastable phase with small size(20 nm or so) was produced in the alloy,its melting temperature range was 464~518.2 ℃,which was higher than that of Al3Mg2 phase(453~465 ℃) under normal pressure.These metastable phases located in the interdendritic position.It was the first time that the metastable phase was found in Al-Mg alloy at a high pressure of 6 GPa.The formation mechanism of the metastable phases was discussed.展开更多
The high-Mg volcanic rocks of the Yixian Formation in the Sihetun area have the obvious characteristics of mantie-derived lava in rare earth, trace element characteristics with high Mg # (62 - 70) and high content o...The high-Mg volcanic rocks of the Yixian Formation in the Sihetun area have the obvious characteristics of mantie-derived lava in rare earth, trace element characteristics with high Mg # (62 - 70) and high content of compatible elements. In the meantime, the volcanic rocks also have the obvious characteristics of Crust-source material in rare earth, trace element characteristics with high ∑ REE ( 158.78 × 10^-6 - 359.66 × 10^-6 ), high (La/Yb) N ( 14.61 - 29.60), high La/Nb(2.37 - 7.52) and high Ba/Nb (67.58- 205.96), obvious positive anomaly of Pb and negative anomaly of Nb, Ta in trace element spider-gram. In Sr-Nd-Pb isotope the (^87Sr/^86Sr)i ratio is higher than 0.706 and the εNd( t ) ratio is from - 3.4 to - 13, both reflect enriched Mantle characteristics. The characteristics above of the volcanic rocks combined with the content of Sr, Ba, Y, Yb and the ratio of Sr/Y show that the volcanic rocks have the property of the Sanukite rocks in Setouchi Japan beside subduction zone, and illuminate that the Sanukite rocks can be formed not only in island-arc near subduction zone but also in intro-plate. The analysis indicates that the high-Mg volcanic rocks in the Sihetun area result from the collective function of mantle-derived lava and crust-source materials. The result illuminates that the West Liaoning region is very special in tectonic geochemical background in Cretaceous in East China, and is an ideal region for us to further study the characteristics of magmatic activity as well as the process of Crust-Mantle interaction in Eastern China.展开更多
基金support from the National Science Foundation of China (No.51971249)the Natural Science Foundation of Shandong Province,China (No.ZR2020KE012)the Science and Technology Planning Project of Longkou City,China (No.2021KJJH025).
基金supported by the Open Fund of State Key Laboratory of Advanced Forming Technology and Equipment (No. SKL202005)the Major Scientific and Technological Innovation Project of Luoyang,China(No. 2201029A)+1 种基金the National Natural Science Foundation of China (Nos. 51771115, 51775334)the Research Program of SAST-SJTU Joint Research Center of Advanced Spaceflight Technologies,China (No. USCAST2020-14)。
基金the National Natural Science Foundation of China (Nos. 52071179, 5227010325)the Natural Science Foundation of Jiangsu Province, China (No. BK20221493)the Fundamental Research Funds for the Central Universities, China (Nos. 30920021160, 30919011405)。
基金supported by the National Key Research and Development Program of China(No.2021YFE0115900)the National Natural Science Foundation of China(Nos.52371016,51871029,and 51571023)the Opening Project of State Key Laboratory for Advanced Metals and Materials(Nos.2020-ZD02 and No.2022-Z03).
文摘This study investigated the influence of graded Zn content on the evolution of precipitated and iron-rich phases and grain struc-ture of the alloys,designed and developed the Al–8.0Zn–1.5Mg–1.5Cu–0.2Fe(wt%)alloy with high strength and formability.With the increase of Zn content,forming the coupling distribution of multiscale precipitates and iron-rich phases with a reasonable matching ratio and dispersion distribution characteristics is easy.This phenomenon induces the formation of cell-like structures with alternate distribu-tion of coarse and fine grains,and the average plasticity–strain ratio(characterizing the formability)of the pre-aged alloy with a high strength is up to 0.708.Results reveal the evolution and influence mechanisms of multiscale second-phase particles and the corresponding high formability mechanism of the alloys.The developed coupling control process exhibits considerable potential,revealing remarkable improvements in the room temperature formability of high-strength Al–Zn–Mg–Cu alloys.
基金financial supports from the Open Project of Key Laboratory of Green Fabrication and Surface Technology of Advanced Metal Materials,Ministry of Education,China (Nos. GFST2021KF04, GFST2021KF09)the Natural Science Research Project of Anhui Educational Committee,China (Nos. KJ2021A0394, KJ2021A0395)Anhui Provincial Natural Science Foundation,China (No. 2208085QE124)。
文摘通过显微组织观察、织构分析和拉伸测试等手段研究挤压比对双相Mg-8Li-6Zn-2Gd合金显微组织、织构和力学性能的影响。结果表明:均匀化态Mg-8Li-6Zn-2Gd合金中含有α-Mg、β-Li、Mg Li Zn、I相和W相。经热挤压后,共晶I相被碾碎成细小颗粒状,而W相保持原有块状形状。合金中α-Mg基体和β-Li基体在热挤压过程中均发生了动态再结晶(DRX),且晶粒随着挤压比的增加逐渐细化。经热挤压后,α-Mg基体的基面织构弱化和柱面织构增强是由于非基面滑移的激活;β-Li基体中形成明显的α和γ纤维织构主要与动态回复与动态再结晶相关。热挤压同时提升Mg-8Li-6Zn-2Gd合金的抗拉强度和伸长率,并在挤压比为16:1时获得最佳的综合力学性能。
基金the National Natural Science Foundation of China(Nos.51822509,51701034)the Scientific and Technological Research Program of Chongqing Municipal Education Commission,China(Nos.KJQN201801137,KJQN201901106)the Basic and Advanced Research Project of CQ CSTC,China(No.cstc2018jcyjAX0035).
基金financial aid from the National Natural Science Foundation(Grant nos.51771178,51671152,51874225)the Key Research and Development Program of Shanxi Province(Grant no.2018ZDXMGY-149)+1 种基金the Youth Innovation Team of Shanxi Universitiesthe Natural Science Foundation of Jilin Province(Grant no.20180414016GH)。
文摘In the current study,a homogenous ultra-fine grained microstructure with average grain size of 1.0μm is achieved in the Mg-Zn-Ca-Mn alloy through the reduplicative equal channel angular pressing(ECAP)at 300℃,and the mechanical properties are remarkably improved,with room-temperature yield strength of 269.6 MPa and elongation of 22.7%.The twinning deformation results in a discontinuous recrystallization behavior in the initial stage of ECAP.With further deformation,the continuously dynamic recrystallization contributes to an obvious grain refinement effect.The activation of non-basal slip system leads to the formation of a unique basal texture,which is related to the elevated ECAP temperature and the decreased grain size.Both grain refinement and texture modification derived from ECAP process result in the increase of yield strength,while the cracked secondary phase particles are beneficial to the enhanced ductility,through reducing the stress concentration and hindering premature failure.
基金the main research program of the Korea Institute of Materials Science(Grant No.PNK8150)for financially supporting this study
文摘In this study,the effects of Al addition on the corrosion behavior of pure Mg with controlled impurity contents were systematically analyzed according to the processing history.The results revealed that the corrosion behavior of high-purity Mg-Al alloys is strongly related to changes in the microstructure,including theβphase and Al-Mn or Al-Fe phases,and the protectiveness of the surface film according to the Al content and processing history.In the as-cast alloys,the corrosion rate increased due to the increase ofβphase as the Al content increased,but in the as-extruded alloys,the corrosion rate,which was high due to intermetallic compounds caused by impurities in the low Al alloy,decreased as the Al content increased,and then increased again.This is due to the combined effect of the increase of theβphase and decrease of the impurity effect,and the increase of the dissolved Al content.The results suggest that it is necessary to analyze the effect of alloying elements on the corrosion behavior of pure Mg with information concerning the impurity content and processing history.
基金The authors gratefully acknowledge the financial support from the National Natural Science Foundation of China(Nos.12072212 and 11832007)the National Key Research and Development Program of China(No.2018YFE0307104)the Applied Basic Research Programs of Sichuan Province(No.2021YJ0071).We also highly appreciate the help of Dr.Yan Li from the Department of Mechanics,Sichuan University.
文摘Magnesium alloys with a long-period stacking ordered(LPSO)structure usually possess excellent static strength,but their fatigue behaviors are poorly understood.This work presents the effect of the LPSO structure on the crack behaviors of Mg alloys in a very high cycle fatigue(VHCF)regime.The LPSO lamellas lead to a facet-like cracking process along the basal planes at the crack initiation site and strongly prohibit the early crack propagation by deflecting the growth direction.The stress intensity factor at the periphery of the faceted area is much higher than the conventional LPSO-free Mg alloys,contributing higher fatigue crack propagation threshold of LPSO-containing Mg alloys.Microstructure observation at the facets reveals a layer of ultrafine grains at the fracture surface due to the cyclic contact of the crack surface,which supports the numerous cyclic pressing model describing the VHCF crack initiation behavior.
基金Financial support from the National Natural Science Foundation of China (21276194)the Specialized Research Fund for the Doctoral Program of Chinese Higher Education (20101208110003)the Key Pillar Program of Tianjin Municipal Science and Technology (11ZCKGX02800)
文摘1 Introduction As the lightest metal with the unique properties of energy production and storage,lithium is regarded as the new century energy metal.Lithium and its compounds were widely used in various industrial fields,especially in
基金Sponsored by the Scientific Research Foundation of Heilongjiang Institute of Science and Technology for the Introduction of High-Qualified Talents(Grant No.08-12)Department of Education of Heilongjiang Province Science and Technology Research Projects(Grant No.12523042)
文摘High pressure solidification rules of Al-Mg alloy needs to be discussed further for its wide range of application. Microstructures and phases of Al-25wt% Mg alloy solidified at 4 GPa were studied by optical microscope,X-ray diffractmeter,energy dispersive X-ray spectroscopy and transmission electron microscopy( TEM). The microstructure evolution mechanism of Al-25Mg alloy under high pressure was analyzed. The result shows that the alloy consists of α-Al phase and Al 3 Mg 2 phase under normal pressure. However,only Al 12 Mg 17 phase forms without Al 3 Mg 2 phase at 4 GPa. In addition,Mg concentration in α-Al phase increases and that of the lattice constant also increases. The α-Al dendrite presents the broken arms under normal pressure, after high pressure solidification,the morphology of the dendrite tends to integrate and the size of the dendrite arms
基金This work is financially supported by the Science Foundation of Harbin Institute of Technology ( No HIT2002 29)
文摘The non-equilibrium microstructure and a new metastable phase of Al-9.6wt%Mg alloy solidified at 6 GPa were studied by optical microscope,differential scanning calorimetry,X-ray diffraction and transmission electron microscope.The results showed that dendrite microstructure was refined,and the solid solubility of Mg in α-Al phase increased greatly.Correspondingly,the lattice parameter of α-Al phase increased.Al3Mg2 phases disappeared under high pressure solidification.In particular,a metastable phase with small size(20 nm or so) was produced in the alloy,its melting temperature range was 464~518.2 ℃,which was higher than that of Al3Mg2 phase(453~465 ℃) under normal pressure.These metastable phases located in the interdendritic position.It was the first time that the metastable phase was found in Al-Mg alloy at a high pressure of 6 GPa.The formation mechanism of the metastable phases was discussed.
基金Project supported bythe Chinese National Ministry of Science and Technology (35 ,2000) the Chinese Ministry of Land andResources (200413000024 ,2000010403)
文摘The high-Mg volcanic rocks of the Yixian Formation in the Sihetun area have the obvious characteristics of mantie-derived lava in rare earth, trace element characteristics with high Mg # (62 - 70) and high content of compatible elements. In the meantime, the volcanic rocks also have the obvious characteristics of Crust-source material in rare earth, trace element characteristics with high ∑ REE ( 158.78 × 10^-6 - 359.66 × 10^-6 ), high (La/Yb) N ( 14.61 - 29.60), high La/Nb(2.37 - 7.52) and high Ba/Nb (67.58- 205.96), obvious positive anomaly of Pb and negative anomaly of Nb, Ta in trace element spider-gram. In Sr-Nd-Pb isotope the (^87Sr/^86Sr)i ratio is higher than 0.706 and the εNd( t ) ratio is from - 3.4 to - 13, both reflect enriched Mantle characteristics. The characteristics above of the volcanic rocks combined with the content of Sr, Ba, Y, Yb and the ratio of Sr/Y show that the volcanic rocks have the property of the Sanukite rocks in Setouchi Japan beside subduction zone, and illuminate that the Sanukite rocks can be formed not only in island-arc near subduction zone but also in intro-plate. The analysis indicates that the high-Mg volcanic rocks in the Sihetun area result from the collective function of mantle-derived lava and crust-source materials. The result illuminates that the West Liaoning region is very special in tectonic geochemical background in Cretaceous in East China, and is an ideal region for us to further study the characteristics of magmatic activity as well as the process of Crust-Mantle interaction in Eastern China.