The effects of Y on the microstructure and mechanical properties of Mg-6Zn-lMn alloy were investigated. The results show that the addition of Y has significant effect on the phase composition, microstructure and mecha...The effects of Y on the microstructure and mechanical properties of Mg-6Zn-lMn alloy were investigated. The results show that the addition of Y has significant effect on the phase composition, microstructure and mechanical properties of Mg-6Zn-lMn alloy. Varied phases compositions, including Mg7Zn3, I-phase （Mg3YZn6）, W-phase （Mg3Y2Zn3） and X-phase （MgI2YZn）, are obtained by adjusting the Zn to Y mass ratio. Mn element exists as the fine Mn particles, which are well distributed in the alloy. Thermal analysis and microstructure observation reveal that the phase stability follows the trend of X〉W〉/〉MgTZn3. In addition, Y can improve the mechanical properties of Mg-Zn-Mn alloy significantly, and the alloy with Y content of 6.09% has the best mechanical properties. The high strength is mainly due to the strengthening by the grain size refinement, dispersion strengthening by fine Mn particles, and introduction of the Mg-Zn-Y ternary phases.展开更多
The microstructures and mechanical properties of Mg-6Zn-1Mn-4Sn and Mg-6Zn-1Mn-4Sn-0.5Y alloys under extrusion and T6 aging conditions were investigated by optical microscopy（OM）, X-ray diffraction（XRD）, scanning ...The microstructures and mechanical properties of Mg-6Zn-1Mn-4Sn and Mg-6Zn-1Mn-4Sn-0.5Y alloys under extrusion and T6 aging conditions were investigated by optical microscopy（OM）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and tensile test. The results show that Y element refines the grains and improves the comprehensive mechanical properties of ZMT614-0.5Y both in as-extruded and T6 states. The phase compositions of Mg-6Zn-1Mn-4Sn-0.5Y are α-Mg, Mg Zn2, Mn, Mg2 Sn and Mg Sn Y phases. After T6 treatment, the ultimate tensile strength（UTS） and yield strength（YS） increase while the elongation decreases severely. For both of these alloys, the theoretical results combined with the experimental values demonstrate that the grain boundary strengthening and solid solution strengthening play an important role in enhancing the YS in the as-extruded state, while the precipitation strengthening is the key factor for the enhancement of YS in the T6 state.展开更多
In order to broaden the application of wrought Mg alloy sheets in the automotive industry,the influence of Ca and Sm alloying on the texture evolution,mechanical properties,and formability of a hot-rolled Mg-2Zn-0.2Mn...In order to broaden the application of wrought Mg alloy sheets in the automotive industry,the influence of Ca and Sm alloying on the texture evolution,mechanical properties,and formability of a hot-rolled Mg-2Zn-0.2Mn alloy was investigated by OM,XRD,SEM,EBSD,tensile tests,and Erichsen test.The results showed that the average grain size and basal texture intensity of Mg-2Zn-0.2Mn alloys were remarkably decreased after Ca and Sm additions.0.64 wt.%Ca or 0.48 wt.%Sm addition significantly increased the tensile strength,ductility and formability.Moreover,the synergetic addition of Sm and Ca improved the ductility and formability of Mg-2Zn-0.2Mn alloy,which was due to the change of Ca distribution and further reduction of the size of Ca-containing particles by Sm addition.The results provided a possibility of replacing RE elements with Ca and Sm in Mg alloys which bring about outstanding mechanical properties and formability.展开更多
The roles of Zn content and thermo-mechanical treatment in affecting microstructures and mechanical properties of Mg-x%Zn-1%Mn（mass fraction,x=4,5,6,7,8,9） wrought Mg alloys were investigated.The microstructure was ...The roles of Zn content and thermo-mechanical treatment in affecting microstructures and mechanical properties of Mg-x%Zn-1%Mn（mass fraction,x=4,5,6,7,8,9） wrought Mg alloys were investigated.The microstructure was extremely refined by dynamic recrystallization（DRC） during extrusion.With increasing Zn content,the DRC grains tended to grow up,at the same time,more second phase streamlines would be present,which restricted the further growing.During solution treatment,the DRC grains would rapidly grow up;however,higher Zn content could hinder the grain boundary expanding,which results in finer ultimate grains.MgZn2 dispersoid particles which are coherent with the matrix would precipitate from the supersaturated solid solution during the one-step aging process,and nano-sized GP zones formed during the pre-aging stage of the two-step aging provide a huge amount of effective nuclei for the MgZn2 phases formed in the second stage,which makes the MgZn2 particles much finer and more dispersed.The mechanical properties of as-extruded samples were not so sensitive to the variation of Zn content,the tensile strength fluctuates between 300 and 320 MPa,and the elongation maintains a high value between 11% and 14%.The strength of aged samples rises as a parabolic curve with increasing Zn content,specifically,the tensile strength of one-step aged samples rises from 278 to 374 MPa,and that of two-step aged ones rises from 284 to 378 MPa,yet the elongation of all aged samples is below 8%.When Zn content exceeds its solid solution limit in Mg-Zn system（6.2%,mass fraction）,the strength rises slowly but the elongation deteriorates sharply,so a Mg-Zn-Mn alloy with 6% Zn possesses the best mechanical properties,that is,the tensile strengths after one-and two-step aging are 352 and 366 MPa,respectively,and the corresponding elongations are 7.98% and 5.2%,respectively.展开更多
The microstructure and properties of the as-cast,as-homogenized and as-extruded Mg−6Zn−4Sn−1Mn(ZTM641)alloy with various Al contents(0,0.5,1,2,3 and 4 wt.%)were investigated by OM,XRD,DSC,SEM,TEM and uniaxial tensile ...The microstructure and properties of the as-cast,as-homogenized and as-extruded Mg−6Zn−4Sn−1Mn(ZTM641)alloy with various Al contents(0,0.5,1,2,3 and 4 wt.%)were investigated by OM,XRD,DSC,SEM,TEM and uniaxial tensile tests.The results show that when the Al content is not higher than 0.5%,the alloys are mainly composed of α-Mg,Mg_(2)Sn,Al_(8)Mn_(5)and Mg_(7)Zn_(3)phases.When the Al content is higher than 0.5%,the alloys mainly consist ofα-Mg,Mg_(2)Sn,MgZn,Mg_(32)(Al,Zn)_(49),Al_(2)Mg_(5)Zn_(2),Al_(11)Mn_(4)and Al_(8)Mn_(5)phases.A small amount of Al(≤1%)can increase the proportion of fine dynamic recrystallized(DRXed)grains during hot-extrusion process.The roomtemperature tensile test results show that the ZTM641−1Al alloy has the best comprehensive mechanical properties,in which the ultimate tensile strength is 332 MPa,yield strength is 221 MPa and the elongation is 15%.Elevatedtemperature tensile test results at 150 and 200℃ show that ZTM641−2Al alloy has the best comprehensive mechanical properties.展开更多
The influence of Mn content on the microstructure,tensile properties and strain-hardening behaviors of extruded Mg−1Gd−0.5Zn−xMn(x=0,0.3 and 1,wt.%)alloy sheets was investigated by X-ray diffraction(XRD),scanning elec...The influence of Mn content on the microstructure,tensile properties and strain-hardening behaviors of extruded Mg−1Gd−0.5Zn−xMn(x=0,0.3 and 1,wt.%)alloy sheets was investigated by X-ray diffraction(XRD),scanning electron microscope(SEM),and electron backscatter diffraction(EBSD).The results show that the completely recrystallized grain structure and the extrusion direction(ED)-titling texture are observed in all the extruded sheets.The mean grain size and weakened ED-titling texture of the extruded sheets are gradually reduced with increasing Mn content.This is primarily associated with the formation of new fineα-Mn particles by Mn addition.Tensile properties show that the addition of Mn also leads to the improvement of yield strengths,ultimate tensile strengths and elongations of the extruded Mg−1Gd−0.5Zn−xMn sheets,which is mainly due to the fine grains andα-Mn particles.In addition,the Mg−1Gd−0.5Zn−1Mn sheet has the lowest strain-hardening exponent and the best hardening capacity among all prepared Mg−1Gd−0.5Zn−xMn sheets.展开更多
Mg−1Mn−0.5Al−0.5Ca−0.5Zn(wt.%)alloy was fabricated by conventional extrusion at 673 K with an extrusion ratio of 25:1,followed by aging at 473 K.The microstructure was characterized by scanning electron microscopy,ele...Mg−1Mn−0.5Al−0.5Ca−0.5Zn(wt.%)alloy was fabricated by conventional extrusion at 673 K with an extrusion ratio of 25:1,followed by aging at 473 K.The microstructure was characterized by scanning electron microscopy,electron back-scattered diffraction,and transmission electron microscopy.The mechanical properties were determined by the tensile test.The peak-aged sample shows fine recrystallized grains with an average grain size of 1.7μm.Area fraction of Al−Ca particles in the alloy increases significantly after peak aging.Meanwhile,botháañandác+añdislocations were observed to remain in the alloy after hot extrusion.Thus,the peak-aged sample exhibits simultaneously high strength and good ductility with the ultimate tensile stress,tensile yield stress,and tension fracture elongation of 320 MPa,314 MPa,and 19.0%,respectively.展开更多
Biodegradable Zn-based alloys, particularly Zn-Mg alloys with the addition of alloying elements, have been intensively investigated aiming to improve both mechanical properties and corrosion behavior. Since such prope...Biodegradable Zn-based alloys, particularly Zn-Mg alloys with the addition of alloying elements, have been intensively investigated aiming to improve both mechanical properties and corrosion behavior. Since such properties are strongly dependent on the alloy microstructure, any evaluation should commence on understanding the conditions influencing its formation. In this study, the effect of the solidification cooling rate on the microstructural evolution of Zn-1 wt.%Mg-(0.5 wt.%Ca, 0.5 wt.%Mn) alloys during transient solidification was investigated. The results show that the microstructures of both alloys have three phases in common: η-Zn dendritic matrix, intermetallic compounds(IMCs) Zn11Mg2, and Zn2 Mg in the eutectic mixture. MnZn9 and two Ca-bearing phases(CaZn11 and CaZn13) are associated with Mn and Ca additions, respectively. These additions are shown to refine the dendritic matrix and the eutectic mixture as compared to the Zn-1 wt.%Mg alloy. A correlation between cooling rate, dendritic or eutectic spacings was developed, thus permitting experimental growth laws to be proposed. Additionally, hardness tests were performed to evaluate the effects of additions of Ca and Mn. Experimental correlations between Vickers microhardness and secondary dendritic spacings were proposed, showing that the microstructural refinement and characteristic Ca and Mn based IMCs induce an increase in hardness as compared to the binary alloy.展开更多
The as-cast microstructures and mechanical properties of Mg-3Ce-1.2Mn-0.9Sc and Mg-3Ce-1.2Mn-1Zn magnesium alloys were investigated and compared. The results indicate that the Sc-containing alloy mainly consists of α...The as-cast microstructures and mechanical properties of Mg-3Ce-1.2Mn-0.9Sc and Mg-3Ce-1.2Mn-1Zn magnesium alloys were investigated and compared. The results indicate that the Sc-containing alloy mainly consists of α-Mg, Mg12Ce and Mn2Sc phases, and the Zn-containing alloy is mainly composed of α-Mg and Mg12Ce phases. The morphologies of the Mg12Ce phases in the two as-cast alloys are different. The Mg12Ce phases in the Sc- and Zn-containing alloys mainly exhibit particle-like shapes and continuous and/or quasti-continuous nets, respectively. Furthermore, the grains of the Sc-containing alloy are finer than those of the Zn-containing alloy. In addition, the Sc- and Zn-containing alloys have similar as-cast tensile properties at room temperature and 300 °C. However, the Sc-containing alloy exhibits higher creep-resistant properties at 300 °C and 30 MPa for 100 h than the Zn-containing alloy.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52071276)the Natural Science Foundation of Chongqing City,China(No.cstc2020jcyj-msxm X0933)。
基金Project(2007CB613700)supported by the National Basic Research Program of ChinaProject(2011BAE22B01-3)supported by the National Key Technologies R&D Program of China+1 种基金Project(2010DFR50010,2008DFR50040)supported by the International Scientific and Technological Cooperation Program of Ministry of Science and Technology of ChinaProject(CSTC,2010AA4048)supported by Chongqing Science and Technology Commission,China
文摘The effects of Y on the microstructure and mechanical properties of Mg-6Zn-lMn alloy were investigated. The results show that the addition of Y has significant effect on the phase composition, microstructure and mechanical properties of Mg-6Zn-lMn alloy. Varied phases compositions, including Mg7Zn3, I-phase （Mg3YZn6）, W-phase （Mg3Y2Zn3） and X-phase （MgI2YZn）, are obtained by adjusting the Zn to Y mass ratio. Mn element exists as the fine Mn particles, which are well distributed in the alloy. Thermal analysis and microstructure observation reveal that the phase stability follows the trend of X〉W〉/〉MgTZn3. In addition, Y can improve the mechanical properties of Mg-Zn-Mn alloy significantly, and the alloy with Y content of 6.09% has the best mechanical properties. The high strength is mainly due to the strengthening by the grain size refinement, dispersion strengthening by fine Mn particles, and introduction of the Mg-Zn-Y ternary phases.
基金Project(2013CB632200)supported by National Basic Research Program of ChinaProject(2010DFR50010)supported by International Scientific and Technological Cooperation Program of Ministry of Science and Technology of ChinaProject supported by Sharing Fund of Chongqing University’s Large-scale Equipment,China
文摘The microstructures and mechanical properties of Mg-6Zn-1Mn-4Sn and Mg-6Zn-1Mn-4Sn-0.5Y alloys under extrusion and T6 aging conditions were investigated by optical microscopy（OM）, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and tensile test. The results show that Y element refines the grains and improves the comprehensive mechanical properties of ZMT614-0.5Y both in as-extruded and T6 states. The phase compositions of Mg-6Zn-1Mn-4Sn-0.5Y are α-Mg, Mg Zn2, Mn, Mg2 Sn and Mg Sn Y phases. After T6 treatment, the ultimate tensile strength（UTS） and yield strength（YS） increase while the elongation decreases severely. For both of these alloys, the theoretical results combined with the experimental values demonstrate that the grain boundary strengthening and solid solution strengthening play an important role in enhancing the YS in the as-extruded state, while the precipitation strengthening is the key factor for the enhancement of YS in the T6 state.
基金financially supported by the National Key Research and Development Program of China(Nos.2018YFA0702903,2016YFB0701204)the Fundamental Research Funds for the Central Universities,China(No.DUT20GF102)。
文摘In order to broaden the application of wrought Mg alloy sheets in the automotive industry,the influence of Ca and Sm alloying on the texture evolution,mechanical properties,and formability of a hot-rolled Mg-2Zn-0.2Mn alloy was investigated by OM,XRD,SEM,EBSD,tensile tests,and Erichsen test.The results showed that the average grain size and basal texture intensity of Mg-2Zn-0.2Mn alloys were remarkably decreased after Ca and Sm additions.0.64 wt.%Ca or 0.48 wt.%Sm addition significantly increased the tensile strength,ductility and formability.Moreover,the synergetic addition of Sm and Ca improved the ductility and formability of Mg-2Zn-0.2Mn alloy,which was due to the change of Ca distribution and further reduction of the size of Ca-containing particles by Sm addition.The results provided a possibility of replacing RE elements with Ca and Sm in Mg alloys which bring about outstanding mechanical properties and formability.
基金Project(2007CB613700)supported by the National Basic Research Program of ChinaProject(2007BAG06B04)supported by the National Science and Technology Pillar Program During the 11th Five-Year Plan Period,China+1 种基金Project(50725413)supported by the National Natural Science Foundation of ChinaProject(CDJXS10132202)supported by the Fundamental Research Funds for the Central Universities,China
文摘The roles of Zn content and thermo-mechanical treatment in affecting microstructures and mechanical properties of Mg-x%Zn-1%Mn（mass fraction,x=4,5,6,7,8,9） wrought Mg alloys were investigated.The microstructure was extremely refined by dynamic recrystallization（DRC） during extrusion.With increasing Zn content,the DRC grains tended to grow up,at the same time,more second phase streamlines would be present,which restricted the further growing.During solution treatment,the DRC grains would rapidly grow up;however,higher Zn content could hinder the grain boundary expanding,which results in finer ultimate grains.MgZn2 dispersoid particles which are coherent with the matrix would precipitate from the supersaturated solid solution during the one-step aging process,and nano-sized GP zones formed during the pre-aging stage of the two-step aging provide a huge amount of effective nuclei for the MgZn2 phases formed in the second stage,which makes the MgZn2 particles much finer and more dispersed.The mechanical properties of as-extruded samples were not so sensitive to the variation of Zn content,the tensile strength fluctuates between 300 and 320 MPa,and the elongation maintains a high value between 11% and 14%.The strength of aged samples rises as a parabolic curve with increasing Zn content,specifically,the tensile strength of one-step aged samples rises from 278 to 374 MPa,and that of two-step aged ones rises from 284 to 378 MPa,yet the elongation of all aged samples is below 8%.When Zn content exceeds its solid solution limit in Mg-Zn system（6.2%,mass fraction）,the strength rises slowly but the elongation deteriorates sharply,so a Mg-Zn-Mn alloy with 6% Zn possesses the best mechanical properties,that is,the tensile strengths after one-and two-step aging are 352 and 366 MPa,respectively,and the corresponding elongations are 7.98% and 5.2%,respectively.
基金the financial supports from the National Natural Science Foundation of China(No.51701172)Educational Commission of Hunan Province,China(No.20B579)+2 种基金Major Program of Hunan Province,China(No.2018RS3091)China Postdoctoral Science Foundation(No.2018M632977)the Natural Science Foundation of Hunan Province,China(No.2018JJ3504).
文摘The microstructure and properties of the as-cast,as-homogenized and as-extruded Mg−6Zn−4Sn−1Mn(ZTM641)alloy with various Al contents(0,0.5,1,2,3 and 4 wt.%)were investigated by OM,XRD,DSC,SEM,TEM and uniaxial tensile tests.The results show that when the Al content is not higher than 0.5%,the alloys are mainly composed of α-Mg,Mg_(2)Sn,Al_(8)Mn_(5)and Mg_(7)Zn_(3)phases.When the Al content is higher than 0.5%,the alloys mainly consist ofα-Mg,Mg_(2)Sn,MgZn,Mg_(32)(Al,Zn)_(49),Al_(2)Mg_(5)Zn_(2),Al_(11)Mn_(4)and Al_(8)Mn_(5)phases.A small amount of Al(≤1%)can increase the proportion of fine dynamic recrystallized(DRXed)grains during hot-extrusion process.The roomtemperature tensile test results show that the ZTM641−1Al alloy has the best comprehensive mechanical properties,in which the ultimate tensile strength is 332 MPa,yield strength is 221 MPa and the elongation is 15%.Elevatedtemperature tensile test results at 150 and 200℃ show that ZTM641−2Al alloy has the best comprehensive mechanical properties.
基金the National Natural Science Foundation of China(Nos.U1764253,U2037601,52001037 and 51971044)the National Defense Basic Scientific Research Program of China+1 种基金the Chongqing Science and Technology Commission,China(No.cstc2017zdcyzdzx X0006)the Qinghai Science and Technology Program,China(No.2018-GX-A1)。
文摘The influence of Mn content on the microstructure,tensile properties and strain-hardening behaviors of extruded Mg−1Gd−0.5Zn−xMn(x=0,0.3 and 1,wt.%)alloy sheets was investigated by X-ray diffraction(XRD),scanning electron microscope(SEM),and electron backscatter diffraction(EBSD).The results show that the completely recrystallized grain structure and the extrusion direction(ED)-titling texture are observed in all the extruded sheets.The mean grain size and weakened ED-titling texture of the extruded sheets are gradually reduced with increasing Mn content.This is primarily associated with the formation of new fineα-Mn particles by Mn addition.Tensile properties show that the addition of Mn also leads to the improvement of yield strengths,ultimate tensile strengths and elongations of the extruded Mg−1Gd−0.5Zn−xMn sheets,which is mainly due to the fine grains andα-Mn particles.In addition,the Mg−1Gd−0.5Zn−1Mn sheet has the lowest strain-hardening exponent and the best hardening capacity among all prepared Mg−1Gd−0.5Zn−xMn sheets.
基金the financial supports from the Fundamental Research Funds for the Central Universities,China(Nos.2019CDCGCL316,2020CDJDPT001)Chongqing Research Program of Basic Research and Frontier Technology,China(No.cstc2019jcjy-msxmX0539)。
文摘Mg−1Mn−0.5Al−0.5Ca−0.5Zn(wt.%)alloy was fabricated by conventional extrusion at 673 K with an extrusion ratio of 25:1,followed by aging at 473 K.The microstructure was characterized by scanning electron microscopy,electron back-scattered diffraction,and transmission electron microscopy.The mechanical properties were determined by the tensile test.The peak-aged sample shows fine recrystallized grains with an average grain size of 1.7μm.Area fraction of Al−Ca particles in the alloy increases significantly after peak aging.Meanwhile,botháañandác+añdislocations were observed to remain in the alloy after hot extrusion.Thus,the peak-aged sample exhibits simultaneously high strength and good ductility with the ultimate tensile stress,tensile yield stress,and tension fracture elongation of 320 MPa,314 MPa,and 19.0%,respectively.
基金The authors are grateful to FAPESP-São Paulo Research Foundation,Brazil(2014/50502-5 and 2017/16058-9)Capes-Coordenação de Aperfeiçoamento de Pessoal de Nível Superior,Brazil(Funding code 001)and CNPq-National Council for Scientific and Technological Development(406239/2018-5)for their financial supportThe authors would like to thank the Brazilian Nanotechnology National Laboratory–LNNano for allowing us to use its facilities.
文摘Biodegradable Zn-based alloys, particularly Zn-Mg alloys with the addition of alloying elements, have been intensively investigated aiming to improve both mechanical properties and corrosion behavior. Since such properties are strongly dependent on the alloy microstructure, any evaluation should commence on understanding the conditions influencing its formation. In this study, the effect of the solidification cooling rate on the microstructural evolution of Zn-1 wt.%Mg-(0.5 wt.%Ca, 0.5 wt.%Mn) alloys during transient solidification was investigated. The results show that the microstructures of both alloys have three phases in common: η-Zn dendritic matrix, intermetallic compounds(IMCs) Zn11Mg2, and Zn2 Mg in the eutectic mixture. MnZn9 and two Ca-bearing phases(CaZn11 and CaZn13) are associated with Mn and Ca additions, respectively. These additions are shown to refine the dendritic matrix and the eutectic mixture as compared to the Zn-1 wt.%Mg alloy. A correlation between cooling rate, dendritic or eutectic spacings was developed, thus permitting experimental growth laws to be proposed. Additionally, hardness tests were performed to evaluate the effects of additions of Ca and Mn. Experimental correlations between Vickers microhardness and secondary dendritic spacings were proposed, showing that the microstructural refinement and characteristic Ca and Mn based IMCs induce an increase in hardness as compared to the binary alloy.
基金Project (50725413) supported by the National Natural Science Foundation of ChinaProject (2007CB613704) supported by the National Basic Research Program of China+1 种基金Projects (2010AC4085, 2009AB4134) supported by the Chongqing Science and Technology Commission of ChinaProject (2010CSTC-HDLS) supported by the Program for Hundreds of Distinguished Leading Scientists of CQ CSTC, China
文摘The as-cast microstructures and mechanical properties of Mg-3Ce-1.2Mn-0.9Sc and Mg-3Ce-1.2Mn-1Zn magnesium alloys were investigated and compared. The results indicate that the Sc-containing alloy mainly consists of α-Mg, Mg12Ce and Mn2Sc phases, and the Zn-containing alloy is mainly composed of α-Mg and Mg12Ce phases. The morphologies of the Mg12Ce phases in the two as-cast alloys are different. The Mg12Ce phases in the Sc- and Zn-containing alloys mainly exhibit particle-like shapes and continuous and/or quasti-continuous nets, respectively. Furthermore, the grains of the Sc-containing alloy are finer than those of the Zn-containing alloy. In addition, the Sc- and Zn-containing alloys have similar as-cast tensile properties at room temperature and 300 °C. However, the Sc-containing alloy exhibits higher creep-resistant properties at 300 °C and 30 MPa for 100 h than the Zn-containing alloy.
