The effects of Zn content on the microstxucture and the mechanical and corrosion properties of as-cast low-alloyed Mg-xZn~.2Ca alloys （x = 0.6wt%, 2.0wt%, 2.5wt%, hereafter denoted as 0.6Zn, 2.0Zn, and 2.5Zn alloys, ...The effects of Zn content on the microstxucture and the mechanical and corrosion properties of as-cast low-alloyed Mg-xZn~.2Ca alloys （x = 0.6wt%, 2.0wt%, 2.5wt%, hereafter denoted as 0.6Zn, 2.0Zn, and 2.5Zn alloys, respectively） axe investigated. The results show that the Zn content not only influences grain refinement but also induces different phase precipitation behaviors. The as-cast microstxucture of the 0.6Zn alloy is composed of ct-Mg, Mg2Ca, and Ca2Mg6Zn3 phases, whereas 2.0Zn and 2.5Zn alloys only contain ct-Mg and Ca2Mg6Zn3 phases, as revealed by X-ray diffraction （XRD） and txonsmission electron microscopy （TEM） analyses. Moreover, with in- creasing Zn content, both the ultimate tensile strength （UTS） and the elongation to fracture first increase and then decrease. Among the three investigated alloys, the largest UTS （178 MPa） and the highest elongation to fracture （6.5%） are obtained for the 2.0Zn alloy. In addition, the corrosion rate increases with increasing Zn content. This paper provides on updated investigation of the alloy composi- tion-microstxucture-property relationships of different Zn-containing Mg-Zn-Ca alloys.展开更多
A novel extrusion-shearing(ES) composite process was designed to fabricate fine-grained, high strength and tough magnesium alloy. The structural parameters of an ES die were optimized by conducting an orthogonal simul...A novel extrusion-shearing(ES) composite process was designed to fabricate fine-grained, high strength and tough magnesium alloy. The structural parameters of an ES die were optimized by conducting an orthogonal simulation experiment using finite element software Deform-3D, and Mg-3 Zn-0.6 Ca-0.6 Zr(ZXK310) alloy was processed using the ES die. The results show that the optimized structural parameters of ES die are extrusion angle(α) of 90°, extrusion section height(h) of 15 mm and inner fillet radius(r) of 10 mm. After ES at an extrusion temperature and a die temperature of 350 °C, ZXK310 alloy exhibited good ES forming ability, and obvious dynamic recrystallization occurred in the forming area. The grain size decreased from 1.42 μm of extrusion area to 0.85 μm of the forming area. Owing to the pinning of second phase and formation of ultrafine grains, the tensile strength, yield strength and elongation of alloy reached 362 MPa, 289 MPa and 21.7%, respectively.展开更多
The microstructure,mechanical properties and corrosion behavior of quaternary degradable Mg−1Zn−0.2Ca−xAg(x=1,2,4 wt.%)alloy wires,intended as anastomotic nails,were investigated.It was found that these Ag-containing ...The microstructure,mechanical properties and corrosion behavior of quaternary degradable Mg−1Zn−0.2Ca−xAg(x=1,2,4 wt.%)alloy wires,intended as anastomotic nails,were investigated.It was found that these Ag-containing alloy wires mainly consist of Mg matrix and Ag17Mg54 phase,characterized by SEM,EDS,XRD and TEM.Tensile and knotting tests results demonstrate the superior mechanical properties of these alloy wires.Especially,Mg−1Zn−0.2Ca−4Ag alloy exhibits the highest mechanical properties,i.e.an ultimate tensile strength of 334 MPa and an elongation of 8.6%.Moreover,with increasing Ag content,the corrosion rates of these alloy wires remarkably increase due to the formation of more micro-galvanic coupling between Mg matrix and Ag17Mg54 phase,shown by mass loss and scanning Kelvin probe force microscopy(SKPFM)results.The present alloy can be completely degraded within 28 d,satisfying the property requirements of anastomotic nails.展开更多
Biodegradable Mg-based implants are widely used in clinical applications because they exhibit mechanical properties comparable to those of human bone and require no revision surgery for their removal.Among Mg-based al...Biodegradable Mg-based implants are widely used in clinical applications because they exhibit mechanical properties comparable to those of human bone and require no revision surgery for their removal.Among Mg-based alloys,Mg–Zn–Ca–(Mn)alloys have been extensively investigated for medical applications because the constituent elements of these alloys,Mg,Zn,Ca,and Mn,are present in human tissues as nutrient elements.In this study,we investigated the effect of the hot extrusion temperature on the microstructure,mechanical properties,and biodegradation rate of Mg–Zn–Ca–(Mn)alloys.The results showed that the addition of Mn and a decrease in the extrusion temperature resulted in grain refinement followed by an increase in the strength and a decrease in the elongation at fracture of the alloys.The alloys showed different mechanical properties along the directions parallel and perpendicular to the extrusion direction.The corrosion test of the alloys in the Hanks’solution revealed that the addition of Mn significantly reduced the corrosion rate of the alloys.The Mg–2 wt%Zn–0.7 wt%Ca–1 wt%Mn alloy hot-extruded at 300℃ with an ultimate tensile strength of 278MPa,an yield strength of 229MPa,an elongation at fracture of 10%,and a corrosion rate of 0.3 mm/year was found to be suitable for orthopedic implants.展开更多
The microstructure, mechanical, and corrosion properties of extruded low-alloyed Mg xZn 0.2Ca (x=0, 1.0, 2.0, 3.0) alloys were investigated in this study. Findings from scanning electron microscope, X-ray diffraction ...The microstructure, mechanical, and corrosion properties of extruded low-alloyed Mg xZn 0.2Ca (x=0, 1.0, 2.0, 3.0) alloys were investigated in this study. Findings from scanning electron microscope, X-ray diffraction and transmission electron microscopy results indicate that the amount of ternary Ca2Mg6Zn3 phase, as the only secondary phase in 1.0Zn, 2.0Zn, and 3.0Zn alloys, gradually increases with the addition of Zn, while the Mg2Ca phase was observed in the Mg 0.2Ca alloy only. Zn has a strong effect on the orientation and intensity of textures, which also influence mechanical behaviors, as revealed by electron back-scatter diffraction. Among all the alloys, the Mg 2.0Zn 0.2Ca alloy obtains the maximum tensile strength (278 MPa) and yield strength (230 MPa). Moreover, Zn addition has an evident influence on the corrosion properties of Mg xZn 0.2Ca alloy, and Mg 1.0Zn 0.2Ca alloy exhibits the minimum corrosion rate. This paper provides a novel low-alloyed magnesium alloy as a potential biodegradable material.展开更多
The influence of equal channel angular pressing on the tension-compression yield asymmetry of extruded Mg-5.3 Zn-0.6 Ca(weight percent)alloy has been investigated.The microstructure was obviously refined by the large ...The influence of equal channel angular pressing on the tension-compression yield asymmetry of extruded Mg-5.3 Zn-0.6 Ca(weight percent)alloy has been investigated.The microstructure was obviously refined by the large strain during the equal channel angular pressing,accompanied with very fine Ca_(2)Mg_(6)Zn_(3) phases with average diameter of 70 nm.The weak tension-compression yield asymmetry after equal channel angular pressing is mainly attributed to the reduced volume fraction of extension twinning during the compression,because the slope(k)of twinning in Hall-Petch relationship is higher than that of dislocation slip,and the twinning deformation is difficult to take place with decreasing grain size.The basal slip is more active in the alloy after equal channel angular pressing,due to the non-basal texture components,which hinders the twinning activation and reduces the yield asymmetry.Furthermore,the presence of fine precipitate restricts the twinning activation,which also contributes to the reduction of yield asymmetry.展开更多
The microstructure and mechanical properties of as-cast Mg-3.8Zn-2.2Ca alloy with different Ce contents were investigated by both optical and electron microscopy, X-ray diffraction, differential scanning calorimetry a...The microstructure and mechanical properties of as-cast Mg-3.8Zn-2.2Ca alloy with different Ce contents were investigated by both optical and electron microscopy, X-ray diffraction, differential scanning calorimetry analysis, tensile and creep tests. The results indi-cated that adding 0.41 wt.%-1.83 wt.% Ce could refine the grains of the alloy, and the grain size gradually decreased as the Ce content in-creased. Furthermore, addition of either 0.41 wt.% or 0.89 wt.% Ce caused the morphology of the Ca2Mg6Zn3 phase to change partially from semi-continuous block to discrete fine particles. However, after adding 1.83 wt.% Ce, portions of the Ca2Mg6Zn3 and Mg12Ce phases were mixed and this Ca2Mg6Zn3＋Mg12Ce eutectic changed to a different coarse semi-continuous morphology. In addition, addition of 0.41 wt.%-1.83 wt.% Ce improved the tensile and creep properties of the alloy. Amongst these Ce-containing alloys, the alloy with 0.89 wt.% Ce exhibited the best ultimate tensile strength and elongation while the alloy with 1.83 wt.% Ce had the best yield strength and creep properties.展开更多
In the present work, ribbon and 2-mm rod samples of Mg-Zn-Ca-Mn alloys were prepared by meltspinning and copper mold injection methods, respectively. Effects of Mn doping on glass-forming ability and corrosion perform...In the present work, ribbon and 2-mm rod samples of Mg-Zn-Ca-Mn alloys were prepared by meltspinning and copper mold injection methods, respectively. Effects of Mn doping on glass-forming ability and corrosion performance in simulated body fluid of Mg65Zn30Ca5 alloy were studied through X-ray diffraction, scanning electron microscopy, differential scanning calorimeter, and electrochemical and immersion tests. Results show that with the Mn addition increasing, all the ribbon samples are completely in amorphous state. However, the microstructure of 2-mm rod samples transfers from fully amorphous for the Mn-free alloy to almost polycrystalline state with precipitated Mg, Mn, and MgZn phases. Glass-forming ability of Mg65Zn30Ca5 alloy is decreased by Mn addition. Results of electrochemical and immersion tests demon- strate that the Mn-doped samples exhibit more negative corrosion potential and larger corrosion current density, suggesting that the corrosion resistance decreases with doping amount of Mn element increasing.展开更多
The effect of Ce/La misch metal addition on the microstructural evolution of as-cast and as-soluted Mg-5.3Zn-0.5Ca（wt.%） alloys was systematically investigated. It was found that Ce/La could effectively refine the a...The effect of Ce/La misch metal addition on the microstructural evolution of as-cast and as-soluted Mg-5.3Zn-0.5Ca（wt.%） alloys was systematically investigated. It was found that Ce/La could effectively refine the as-cast alloy and restrain grain growth during solution treatment, which was derived from the constitutional supercooling during solidification process and the formation of stable intermetallic compounds Ce Mg12 and Mg17La2. Furthermore, Ce/La microalloying and solution treatment resulted in an evolution from the original lamellar Ca2Mg6Zn3/α-Mg to the divorced eutectic structure. The thermal stability of Mg-Zn-Ca alloy could be effectively improved by Ce/La addition, because the low-melting-point binary Mg-Zn phase was transformed to Mg x Zn y-Ca-（Ce/La） phase with higher thermal stability and the amount of Ca2Mg6Zn3/α-Mg eutectic structure was reduced.展开更多
Mg69Zn27Ca4 alloys with diameters of 1.5, 2 and 3 mm were fabricated using copper mold injection casting method. Microstructural analysis reveals that the alloy with a diameter of 1.5 mm is almost completely composed ...Mg69Zn27Ca4 alloys with diameters of 1.5, 2 and 3 mm were fabricated using copper mold injection casting method. Microstructural analysis reveals that the alloy with a diameter of 1.5 mm is almost completely composed of amorphous phase. However, with the cooling rate decline, a little α-Mg and MgZn dendrites can be found in the amorphous matrix. Based on the microstructural and tensile results, the ductile dendrites are conceived to be highly responsible for the enhanced compressive strain from 1.3% to 3.1% by increasing the sample diameter from 1.5 mm to 3 mm. In addition, the Mg69Zn27Ca4 alloy with 1.5 mm diameter has the best corrosion properties. The current Mg-based alloys show much better corrosion resistance than the traditionally commercial wrought magnesium alloy ZK60 in simulated sea-water.展开更多
The microstructural evolution,texture and mechanical properties of nine Mg-4Zn-xCa-yMn alloys(x=0.3,0.6,1.0;y=0.2,0.3,0.7 wt.%)were investigated systematically.Alloying with Ca and Mn refined the grains of the extrude...The microstructural evolution,texture and mechanical properties of nine Mg-4Zn-xCa-yMn alloys(x=0.3,0.6,1.0;y=0.2,0.3,0.7 wt.%)were investigated systematically.Alloying with Ca and Mn refined the grains of the extruded sheets and increased the unDRX fraction.Mn could be the heterogeneous nucleation site of Ca2Mg6Zn3 phase because of a good atom matching at the orientation relationship of(211)_(Mn)//(1211)_(Ca2Mg6Zn3),(251)_(Mn)//〈1103〉_(Ca2Mg6Zn3).The traditional texture weakening effect of Ca was strongly decreased for the simultaneously addition of Mn.With increasing Ca and Mn concentration,the strength increased and ductility decreased.Mg-4Zn-0.6Ca-0.7Mn exhibited a good combination of ultimate tensile strength(320 MPa),yield strength(286 MPa)and elongation(16%).A model of strengthening indicated that grain boundary strengthening and precipitate strengthening made a large contribution to the strength of Mg-4Zn-0.6Ca-0.7Mn.In addition,the dynamic recrystallization,texture modification and the strengthening effect from different parts also have been analyzed in detail.展开更多
基金supported by the National Natural Science Foundation of China(No.51671017)Fundamental Research Funds for the Central Universities(No.FRF-GF-17-B3)+1 种基金Beijing Laboratory of Metallic Materials and Processing for Modern Transportation,the Opening Research Fund of State Key Laboratory for Advanced Metals and Materials(Nos.2016Z-11,2017Z-08)State's Key Project of Research and Development Plan(No.2016YFB0300801)
文摘The effects of Zn content on the microstxucture and the mechanical and corrosion properties of as-cast low-alloyed Mg-xZn~.2Ca alloys （x = 0.6wt%, 2.0wt%, 2.5wt%, hereafter denoted as 0.6Zn, 2.0Zn, and 2.5Zn alloys, respectively） axe investigated. The results show that the Zn content not only influences grain refinement but also induces different phase precipitation behaviors. The as-cast microstxucture of the 0.6Zn alloy is composed of ct-Mg, Mg2Ca, and Ca2Mg6Zn3 phases, whereas 2.0Zn and 2.5Zn alloys only contain ct-Mg and Ca2Mg6Zn3 phases, as revealed by X-ray diffraction （XRD） and txonsmission electron microscopy （TEM） analyses. Moreover, with in- creasing Zn content, both the ultimate tensile strength （UTS） and the elongation to fracture first increase and then decrease. Among the three investigated alloys, the largest UTS （178 MPa） and the highest elongation to fracture （6.5%） are obtained for the 2.0Zn alloy. In addition, the corrosion rate increases with increasing Zn content. This paper provides on updated investigation of the alloy composi- tion-microstxucture-property relationships of different Zn-containing Mg-Zn-Ca alloys.
基金supported by Liaoning Revitalization Talents Program, China (XLYC1807021)Joint Research Fund of Liaoning - Shenyang National Laboratory for Materials Science, China (2019JH3/30100014)+1 种基金Innovation Talent Program in Sciences and Technologies for Young and Middle-aged Scientists of Shenyang, China (RC200414)Scientific Research Fund of Liaoning Provincial Department of Education, China (LJGD2020008)
文摘A novel extrusion-shearing(ES) composite process was designed to fabricate fine-grained, high strength and tough magnesium alloy. The structural parameters of an ES die were optimized by conducting an orthogonal simulation experiment using finite element software Deform-3D, and Mg-3 Zn-0.6 Ca-0.6 Zr(ZXK310) alloy was processed using the ES die. The results show that the optimized structural parameters of ES die are extrusion angle(α) of 90°, extrusion section height(h) of 15 mm and inner fillet radius(r) of 10 mm. After ES at an extrusion temperature and a die temperature of 350 °C, ZXK310 alloy exhibited good ES forming ability, and obvious dynamic recrystallization occurred in the forming area. The grain size decreased from 1.42 μm of extrusion area to 0.85 μm of the forming area. Owing to the pinning of second phase and formation of ultrafine grains, the tensile strength, yield strength and elongation of alloy reached 362 MPa, 289 MPa and 21.7%, respectively.
基金The authors are grateful for the financial supports from the National Natural Science Foundation of China(51671017 and 51971020)the Beijing Municipal Natural Science Foundation,China(2202033)+2 种基金Beijing Laboratory of Metallic Materials and Processing for Modern Transportation,China,the Fundamental Research Funds for the Central Universities,China(FRF-IC-19-015)the Major State Research and Development Program of China(2016YFB0300801)the Opening Research Fund of State Key Laboratory for Advanced Metals and Materials,China(2018-Z04).
文摘The microstructure,mechanical properties and corrosion behavior of quaternary degradable Mg−1Zn−0.2Ca−xAg(x=1,2,4 wt.%)alloy wires,intended as anastomotic nails,were investigated.It was found that these Ag-containing alloy wires mainly consist of Mg matrix and Ag17Mg54 phase,characterized by SEM,EDS,XRD and TEM.Tensile and knotting tests results demonstrate the superior mechanical properties of these alloy wires.Especially,Mg−1Zn−0.2Ca−4Ag alloy exhibits the highest mechanical properties,i.e.an ultimate tensile strength of 334 MPa and an elongation of 8.6%.Moreover,with increasing Ag content,the corrosion rates of these alloy wires remarkably increase due to the formation of more micro-galvanic coupling between Mg matrix and Ag17Mg54 phase,shown by mass loss and scanning Kelvin probe force microscopy(SKPFM)results.The present alloy can be completely degraded within 28 d,satisfying the property requirements of anastomotic nails.
基金The authors gratefully acknowledge the financial support from the Ministry of Science and Higher Education of the Russian Federation in the framework of Increase Competitiveness Program of NUST 《MISiS》(№ К2-2019-008)implemented by a governmental decree dated 16th of March 2013,N 211.
文摘Biodegradable Mg-based implants are widely used in clinical applications because they exhibit mechanical properties comparable to those of human bone and require no revision surgery for their removal.Among Mg-based alloys,Mg–Zn–Ca–(Mn)alloys have been extensively investigated for medical applications because the constituent elements of these alloys,Mg,Zn,Ca,and Mn,are present in human tissues as nutrient elements.In this study,we investigated the effect of the hot extrusion temperature on the microstructure,mechanical properties,and biodegradation rate of Mg–Zn–Ca–(Mn)alloys.The results showed that the addition of Mn and a decrease in the extrusion temperature resulted in grain refinement followed by an increase in the strength and a decrease in the elongation at fracture of the alloys.The alloys showed different mechanical properties along the directions parallel and perpendicular to the extrusion direction.The corrosion test of the alloys in the Hanks’solution revealed that the addition of Mn significantly reduced the corrosion rate of the alloys.The Mg–2 wt%Zn–0.7 wt%Ca–1 wt%Mn alloy hot-extruded at 300℃ with an ultimate tensile strength of 278MPa,an yield strength of 229MPa,an elongation at fracture of 10%,and a corrosion rate of 0.3 mm/year was found to be suitable for orthopedic implants.
基金The Major State Research and Development Program of China (No. 2016YFB0300801)the National Natural Science Foundation of China (Nos. 51671017 and 51971020)+3 种基金the Fundamental Research Funds for the Central Universities (No. FRF-IC-19-010)Beijing Laboratory of Metallic Materials and Processing for Modern Transportationthe fund of the State Key Laboratory of Solidification Processing in NWPU (No. SKLSP201835)the Opening Research Fund of State Key Laboratory for Advanced Metals and Materials (2018-Z04)
文摘The microstructure, mechanical, and corrosion properties of extruded low-alloyed Mg xZn 0.2Ca (x=0, 1.0, 2.0, 3.0) alloys were investigated in this study. Findings from scanning electron microscope, X-ray diffraction and transmission electron microscopy results indicate that the amount of ternary Ca2Mg6Zn3 phase, as the only secondary phase in 1.0Zn, 2.0Zn, and 3.0Zn alloys, gradually increases with the addition of Zn, while the Mg2Ca phase was observed in the Mg 0.2Ca alloy only. Zn has a strong effect on the orientation and intensity of textures, which also influence mechanical behaviors, as revealed by electron back-scatter diffraction. Among all the alloys, the Mg 2.0Zn 0.2Ca alloy obtains the maximum tensile strength (278 MPa) and yield strength (230 MPa). Moreover, Zn addition has an evident influence on the corrosion properties of Mg xZn 0.2Ca alloy, and Mg 1.0Zn 0.2Ca alloy exhibits the minimum corrosion rate. This paper provides a novel low-alloyed magnesium alloy as a potential biodegradable material.
基金The authors wish to highly acknowledge Prof.L.M.Wang of Changchun Institute of Applied Chemistry,Chinese Academy of Sciences,for his valuable suggestions and discussions.Thanks to the financial aid from the National Science&Technology Pillar Program(Grant No.2012BAE01B04)the National Natural Science Foundation of China(Grant No.51401200)the Natural Science Foundation of Jilin Province(Grant No.20140520099JH).
文摘The influence of equal channel angular pressing on the tension-compression yield asymmetry of extruded Mg-5.3 Zn-0.6 Ca(weight percent)alloy has been investigated.The microstructure was obviously refined by the large strain during the equal channel angular pressing,accompanied with very fine Ca_(2)Mg_(6)Zn_(3) phases with average diameter of 70 nm.The weak tension-compression yield asymmetry after equal channel angular pressing is mainly attributed to the reduced volume fraction of extension twinning during the compression,because the slope(k)of twinning in Hall-Petch relationship is higher than that of dislocation slip,and the twinning deformation is difficult to take place with decreasing grain size.The basal slip is more active in the alloy after equal channel angular pressing,due to the non-basal texture components,which hinders the twinning activation and reduces the yield asymmetry.Furthermore,the presence of fine precipitate restricts the twinning activation,which also contributes to the reduction of yield asymmetry.
基金Project supported by the National Natural Science Foundation of China (50725413)the Major State Basic Research Development Program of China (973) (2007CB613704)+1 种基金the Chongqing Science and Technology Commission in China (CSTC, 2011ggB50013, 2011jjA50019, 2011AC4119 and 2010AC4085)the Program for Hundreds of Distinguished Leading Scientists of CQ CSTC (2010CSTC-HDLS)
文摘The microstructure and mechanical properties of as-cast Mg-3.8Zn-2.2Ca alloy with different Ce contents were investigated by both optical and electron microscopy, X-ray diffraction, differential scanning calorimetry analysis, tensile and creep tests. The results indi-cated that adding 0.41 wt.%-1.83 wt.% Ce could refine the grains of the alloy, and the grain size gradually decreased as the Ce content in-creased. Furthermore, addition of either 0.41 wt.% or 0.89 wt.% Ce caused the morphology of the Ca2Mg6Zn3 phase to change partially from semi-continuous block to discrete fine particles. However, after adding 1.83 wt.% Ce, portions of the Ca2Mg6Zn3 and Mg12Ce phases were mixed and this Ca2Mg6Zn3＋Mg12Ce eutectic changed to a different coarse semi-continuous morphology. In addition, addition of 0.41 wt.%-1.83 wt.% Ce improved the tensile and creep properties of the alloy. Amongst these Ce-containing alloys, the alloy with 0.89 wt.% Ce exhibited the best ultimate tensile strength and elongation while the alloy with 1.83 wt.% Ce had the best yield strength and creep properties.
基金financially supported by the National Natural Science Foundation of China (Nos. 51201120 and 51401155)the Science & Technology Coordination & Innovation Project of Shaanxi Province(No. 2016KTZDGY-04-01)the Key Laboratory Program Funded by Shaanxi Provincial Education Department(No.17JS053)
文摘In the present work, ribbon and 2-mm rod samples of Mg-Zn-Ca-Mn alloys were prepared by meltspinning and copper mold injection methods, respectively. Effects of Mn doping on glass-forming ability and corrosion performance in simulated body fluid of Mg65Zn30Ca5 alloy were studied through X-ray diffraction, scanning electron microscopy, differential scanning calorimeter, and electrochemical and immersion tests. Results show that with the Mn addition increasing, all the ribbon samples are completely in amorphous state. However, the microstructure of 2-mm rod samples transfers from fully amorphous for the Mn-free alloy to almost polycrystalline state with precipitated Mg, Mn, and MgZn phases. Glass-forming ability of Mg65Zn30Ca5 alloy is decreased by Mn addition. Results of electrochemical and immersion tests demon- strate that the Mn-doped samples exhibit more negative corrosion potential and larger corrosion current density, suggesting that the corrosion resistance decreases with doping amount of Mn element increasing.
基金supported by the National Natural Science Foundation of China(51401200)Natural Science Foundation of Jilin Province(20140520099JH)+4 种基金National Science & Technology Pillar Program(2012BAE01B04)Chinese Academy of Sciences of Western Action Plan Project(KZCX2-XB3-06)the National Natural Science Foundation of China Major Project(91122030)National High Technology Research and Development Program of China(2011AA03A407)National Natural Science Foundation for Creative Research Group(20921002)
文摘The effect of Ce/La misch metal addition on the microstructural evolution of as-cast and as-soluted Mg-5.3Zn-0.5Ca（wt.%） alloys was systematically investigated. It was found that Ce/La could effectively refine the as-cast alloy and restrain grain growth during solution treatment, which was derived from the constitutional supercooling during solidification process and the formation of stable intermetallic compounds Ce Mg12 and Mg17La2. Furthermore, Ce/La microalloying and solution treatment resulted in an evolution from the original lamellar Ca2Mg6Zn3/α-Mg to the divorced eutectic structure. The thermal stability of Mg-Zn-Ca alloy could be effectively improved by Ce/La addition, because the low-melting-point binary Mg-Zn phase was transformed to Mg x Zn y-Ca-（Ce/La） phase with higher thermal stability and the amount of Ca2Mg6Zn3/α-Mg eutectic structure was reduced.
基金Project(NCET-11-0554)supported by the Program for New Century Excellent Talents in UniversityProject(2011BAE22B04)supportedby the National Key Technology R&D Program of ChinaProject(51271206)supported by the National Natural Science Foundation of China
文摘Mg69Zn27Ca4 alloys with diameters of 1.5, 2 and 3 mm were fabricated using copper mold injection casting method. Microstructural analysis reveals that the alloy with a diameter of 1.5 mm is almost completely composed of amorphous phase. However, with the cooling rate decline, a little α-Mg and MgZn dendrites can be found in the amorphous matrix. Based on the microstructural and tensile results, the ductile dendrites are conceived to be highly responsible for the enhanced compressive strain from 1.3% to 3.1% by increasing the sample diameter from 1.5 mm to 3 mm. In addition, the Mg69Zn27Ca4 alloy with 1.5 mm diameter has the best corrosion properties. The current Mg-based alloys show much better corrosion resistance than the traditionally commercial wrought magnesium alloy ZK60 in simulated sea-water.
基金supported by National Key R&D Program of China(2016YFB0301100)National Natural Science Foundation of China(51571043)Fundamental Research Funds for the Central Universities(2020CDJDPT001,cqu2018CDHB1A08)。
文摘The microstructural evolution,texture and mechanical properties of nine Mg-4Zn-xCa-yMn alloys(x=0.3,0.6,1.0;y=0.2,0.3,0.7 wt.%)were investigated systematically.Alloying with Ca and Mn refined the grains of the extruded sheets and increased the unDRX fraction.Mn could be the heterogeneous nucleation site of Ca2Mg6Zn3 phase because of a good atom matching at the orientation relationship of(211)_(Mn)//(1211)_(Ca2Mg6Zn3),(251)_(Mn)//〈1103〉_(Ca2Mg6Zn3).The traditional texture weakening effect of Ca was strongly decreased for the simultaneously addition of Mn.With increasing Ca and Mn concentration,the strength increased and ductility decreased.Mg-4Zn-0.6Ca-0.7Mn exhibited a good combination of ultimate tensile strength(320 MPa),yield strength(286 MPa)and elongation(16%).A model of strengthening indicated that grain boundary strengthening and precipitate strengthening made a large contribution to the strength of Mg-4Zn-0.6Ca-0.7Mn.In addition,the dynamic recrystallization,texture modification and the strengthening effect from different parts also have been analyzed in detail.
