Microstructure and tensile properties of a Mg-Sm-Zn-Zr alloy with various extrusion ratios(ERs)of 6.9,10.4 and 17.6 were systematically investigated.It was identified that,greater ER increased dynamic recrystallizatio...Microstructure and tensile properties of a Mg-Sm-Zn-Zr alloy with various extrusion ratios(ERs)of 6.9,10.4 and 17.6 were systematically investigated.It was identified that,greater ER increased dynamic recrystallization(DRX)fraction and coarsened DRX grains,which further suggests weakened basal fiber texture for the studied alloy.This is mainly due to the rising temperature from massive deformation heat when hot-extrusion.As a result,greater ER corresponds to a decreased strength but improved ductility.Finally,transmission electron microscopy(TEM)observations reveal that the dominant intermetallic phase,Mg_(3)Sm,is metastable,and it will transform into Mg_(41)Sm_(5)during extrusion with high-ER.This transformation leads to the accumulation of surplus Sm and Zn atoms,which induces the precipitation of Sm Zn_(3)phase at the surface of Mg_(41)Sm_(5)matrix.展开更多
The microstructure and tensile properties of the Mg-1.0%Sn-xY(x=1.5%,3.0%,3.5%,atom fraction)alloys extruded indirectly at 350℃ were investigated by means of optical microscopy,scanning electron microscopy and tensil...The microstructure and tensile properties of the Mg-1.0%Sn-xY(x=1.5%,3.0%,3.5%,atom fraction)alloys extruded indirectly at 350℃ were investigated by means of optical microscopy,scanning electron microscopy and tensile test.The mean grain sizes ofα-Mg matrix in the three extruded alloys are 6,8 and 12μm,respectively,slightly increasing with the addition of Y. The relationship between microstructure and strength was discussed in detail.The results show that the addition of Y has little effect on the grain refinement of the as-extruded Mg-Sn based alloys above.The only MgSnY phase is detected in the Mg-Sn-1.5%Y alloy, and the Sn3Y5 phase in the Mg-Sn-3.5%Y alloy,whereas both of them simultaneously exist in the Mg-Sn-3.0%Y alloy.The particle shape of MgSnY and Sn3Y5 phase,inherited from the solidification,has little change before and after hot extrusion.Mg-Sn-3.0%Y alloy has the highest ultimate tensile strength(UTS),305 MPa,by over 50%compared with that of the other two alloys.展开更多
The microstructure and mechanical properties of Mg-xSn(x=3,7 and 14,mass fraction,%) alloys extruded indirectly at 300℃ were investigated by means of optical microscopy,scanning electron microscopy and tensile test.T...The microstructure and mechanical properties of Mg-xSn(x=3,7 and 14,mass fraction,%) alloys extruded indirectly at 300℃ were investigated by means of optical microscopy,scanning electron microscopy and tensile test.The grain size of theα-Mg matrix decreases from 220,160 and 93μm after the homogenization treatment to 28,3 and 16μm in the three alloys after extrusion,respectively.The results show that the grain refinement is most remarkable in the as-extruded Mg-7Sn alloy.At the same time,the amount of the Mg2Sn particles remarkably increases in the Mg-7Sn alloy with very uniform distribution in theα-Mg matrix.In contrast,the Mg2Sn phase inherited from the solidification with a large size is mainly distributed along grain boundary in the Mg-14Sn alloy.The tensile tests at room temperature show that the ultimate tensile strength of the as-extruded Mg-7Sn alloy is the highest,i.e.,255 MPa,increased by 120%as compared with that of as-cast samples.展开更多
Indirect extrusion of Mg-10%Sn (mass fraction) alloys was performed at three different working temperatures. The effect of working temperature on the microstructure, texture and tensile properties of the extruded allo...Indirect extrusion of Mg-10%Sn (mass fraction) alloys was performed at three different working temperatures. The effect of working temperature on the microstructure, texture and tensile properties of the extruded alloys was investigated by optical microscope (OM), scanning electronic microscope (SEM), X-ray diffraction (XRD) and a standard universal testing machine. Grain size, area fraction of second phase particles and texture of the alloys are found to be significantly influenced by working temperature. The grain size refinement is greatly dependent on processing conditions with the low working temperature being the most effective. While the high working temperature results in a coarser grain size and a stronger fiber texture and the reason for this phenomenon was examined in terms of second phase particle, grain type and dynamic recrystallization mechanism. Tested in the different conditions, the tensile strengths of the Mg-10Sn alloys extruded at the high working temperature are remarkably better than those of the other studied alloys. This significant improvement in tensile properties is mainly due to the particle strengthening and texture strengthening resulted from the more and finer primary dispersed particles and stronger texture, respectively.展开更多
Microstructure of as-cast and extruded Mg-8Li-1Al-1Y alloy specimens was analyzed with OM,SEM and XRD.Results show that as-cast specimens are composed of α phase(Mg),β phase(Li) and rod-like Al2Y compound.In the ext...Microstructure of as-cast and extruded Mg-8Li-1Al-1Y alloy specimens was analyzed with OM,SEM and XRD.Results show that as-cast specimens are composed of α phase(Mg),β phase(Li) and rod-like Al2Y compound.In the extruded specimens,the microstructure is refined and the β phase has the effect of coordination during deformation.After extruding process,the Al2Y compound distributes evenly in the extruding direction.The results of mechanical properties tests show that the strength and elongation are both improved after extruding deformation.展开更多
Through an investigation of the microstructure and mechanical properties of extruded Mg–5Bi–x Sn(BT5x, x = 0, 2, 4, and 6 wt%) alloys,this study demonstrates that the addition of Sn to an Mg–5Bi binary alloy signif...Through an investigation of the microstructure and mechanical properties of extruded Mg–5Bi–x Sn(BT5x, x = 0, 2, 4, and 6 wt%) alloys,this study demonstrates that the addition of Sn to an Mg–5Bi binary alloy significantly improves the tensile strength of the extruded alloy.All the extruded alloys exhibit a typical basal fiber texture and a partially dynamically recrystallized(DRXed) microstructure consisting of fine DRXed grains and coarse un DRXed grains. As the Sn content increases from 0 wt% to 6 wt%, the average size of the DRXed grains decreases from 4.2 to 2.8 μm owing to the increase in the amount of precipitates via their grain-boundary pinning effect. The extruded B5 and BT52 alloys contain numerous Mg_(3)Bi_(2) precipitates, but their size and number density are smaller and higher, respectively, in the latter alloy.Numerous Mg_(2)Sn precipitates as well as Mg_(3)Bi_(2)precipitates are present in the extruded BT54 and BT56 alloys, and the number density of the Mg_(2)Sn precipitates is higher in the latter alloy because of its higher Sn content. The addition of 2 wt% Sn to the B5 alloy significantly improves the yield strength(YS) and ultimate tensile strength(UTS) of the extruded alloy—by 76 and 57 MPa, respectively. This drastic improvement is the combined outcome of enhanced grain-boundary hardening, precipitation hardening, and solid-solution hardening effects induced by the refined DRXed grains, numerous precipitates, and Sn solute atoms, respectively. The further addition of 2 wt% or 4 wt% Sn to the BT52 alloy leads to moderate increments in the YS and UTS of the extruded alloy. Specifically, each addition of 2 wt% Sn increases the YS and UTS by ~26 and ~20 MPa, respectively, which is attributed mainly to the additional precipitation hardening effect induced by the Mg_(2)Sn precipitates.展开更多
The microstructure of as-cast and extruded Mg-14 Li-1 Al-(0, 0.3) La alloys was examined with XRD,OM, SEM, and EDS. The mechanical properties of the extruded specimens with and without La were compared. The results ...The microstructure of as-cast and extruded Mg-14 Li-1 Al-(0, 0.3) La alloys was examined with XRD,OM, SEM, and EDS. The mechanical properties of the extruded specimens with and without La were compared. The results show that La addition has an obvious effect on the microstructure of the as-cast LA141 alloy by reducing the average grain size from 600 to 220 μm. β-Li and LiMgAl2 phases are observed in both alloys, and long-rod-shaped Al2 La phase is also observed in the La containing alloy. After extrusion, Al2 La phases are short-rod-shaped and distribute evenly in the alloy. LAl41-0.3 La alloy has higher elongation(34%), which is attributed to refined microstructure and weak texture due to shortrod-like Al2 La phase.展开更多
In this study,the tensile and high-cycle fatigue properties of as-cast,solid solution treated and as-extruded Mg-8Li-3Al-2Zn-0.5Y alloy are investigated.The results show that the yield strength and ultimate tensile st...In this study,the tensile and high-cycle fatigue properties of as-cast,solid solution treated and as-extruded Mg-8Li-3Al-2Zn-0.5Y alloy are investigated.The results show that the yield strength and ultimate tensile strength of as-cast alloy is 198.1 MPa and 222.5 MPa,which are improved to 274.7 MPa and 321.7 MPa,282.4 MPa and 319.3 MPa after solid solution and extrusion treatment,respectively.The high-cycle fatigue strength(at 10^(7)cycles,R=-1)of as-cast studied alloy is 65 MPa,which is improved to 90 MPa and 105 MPa after solid solution and extrusion treatment,respectively.The improvement of fatigue property of the solid solution treated alloy is mainly due to the lattice distortion caused by solid solution hindering the crack propagation.However,the improvement of fatigue property of the as-extruded alloy is mainly due to that the refined grains,stacked dislocations and dispersed secondary particles impede the crack propagation.展开更多
基金supported by the National Natural Science Foundation of China(No.52071093,51871069,51701200)Fundamental Research Funds for the Central Universities(3072020CF1009)+1 种基金the Open Funds of the State Key Laboratory of Rare Earth Resource Utilization(RERU2020012)Grant-in-Aid for JSPS Fellows from the Japan Society for the Promotion of Science。
文摘Microstructure and tensile properties of a Mg-Sm-Zn-Zr alloy with various extrusion ratios(ERs)of 6.9,10.4 and 17.6 were systematically investigated.It was identified that,greater ER increased dynamic recrystallization(DRX)fraction and coarsened DRX grains,which further suggests weakened basal fiber texture for the studied alloy.This is mainly due to the rising temperature from massive deformation heat when hot-extrusion.As a result,greater ER corresponds to a decreased strength but improved ductility.Finally,transmission electron microscopy(TEM)observations reveal that the dominant intermetallic phase,Mg_(3)Sm,is metastable,and it will transform into Mg_(41)Sm_(5)during extrusion with high-ER.This transformation leads to the accumulation of surplus Sm and Zn atoms,which induces the precipitation of Sm Zn_(3)phase at the surface of Mg_(41)Sm_(5)matrix.
基金Project(2008S089)supported by the Key Laboratory Fund of Liaoning Province,ChinaProject(2007010303025)supported by Shenyang Talents Supporting ProgramProject(50731002)supported by the National Natural Science Foundation of China
文摘The microstructure and tensile properties of the Mg-1.0%Sn-xY(x=1.5%,3.0%,3.5%,atom fraction)alloys extruded indirectly at 350℃ were investigated by means of optical microscopy,scanning electron microscopy and tensile test.The mean grain sizes ofα-Mg matrix in the three extruded alloys are 6,8 and 12μm,respectively,slightly increasing with the addition of Y. The relationship between microstructure and strength was discussed in detail.The results show that the addition of Y has little effect on the grain refinement of the as-extruded Mg-Sn based alloys above.The only MgSnY phase is detected in the Mg-Sn-1.5%Y alloy, and the Sn3Y5 phase in the Mg-Sn-3.5%Y alloy,whereas both of them simultaneously exist in the Mg-Sn-3.0%Y alloy.The particle shape of MgSnY and Sn3Y5 phase,inherited from the solidification,has little change before and after hot extrusion.Mg-Sn-3.0%Y alloy has the highest ultimate tensile strength(UTS),305 MPa,by over 50%compared with that of the other two alloys.
基金Project(2008S089)supported by the Key Laboratory Program of Liaoning Province,ChinaProject(2007010303025)supported by the Shenyang Talents Supporting,ChinaProject(50731002)supported by the National Natural Science Foundation of China
文摘The microstructure and mechanical properties of Mg-xSn(x=3,7 and 14,mass fraction,%) alloys extruded indirectly at 300℃ were investigated by means of optical microscopy,scanning electron microscopy and tensile test.The grain size of theα-Mg matrix decreases from 220,160 and 93μm after the homogenization treatment to 28,3 and 16μm in the three alloys after extrusion,respectively.The results show that the grain refinement is most remarkable in the as-extruded Mg-7Sn alloy.At the same time,the amount of the Mg2Sn particles remarkably increases in the Mg-7Sn alloy with very uniform distribution in theα-Mg matrix.In contrast,the Mg2Sn phase inherited from the solidification with a large size is mainly distributed along grain boundary in the Mg-14Sn alloy.The tensile tests at room temperature show that the ultimate tensile strength of the as-extruded Mg-7Sn alloy is the highest,i.e.,255 MPa,increased by 120%as compared with that of as-cast samples.
基金Fo undation item: Proj ect(2012R 1A 1A 1012802) supported by the National Research Foundation of Korea Funded by the Ministry of Education, Science and Technology Project(2013021013-4) supported by Shanxi Province Science Foundation for Youths, China+1 种基金 Project(2012L003) supported by Advanced Programs of Department of Human Resources and Social Security of Shauxi Province for Returned Scholars, China Project supported by Foundation for Young Scholars of Taiyuan University of Technology, China
文摘Indirect extrusion of Mg-10%Sn (mass fraction) alloys was performed at three different working temperatures. The effect of working temperature on the microstructure, texture and tensile properties of the extruded alloys was investigated by optical microscope (OM), scanning electronic microscope (SEM), X-ray diffraction (XRD) and a standard universal testing machine. Grain size, area fraction of second phase particles and texture of the alloys are found to be significantly influenced by working temperature. The grain size refinement is greatly dependent on processing conditions with the low working temperature being the most effective. While the high working temperature results in a coarser grain size and a stronger fiber texture and the reason for this phenomenon was examined in terms of second phase particle, grain type and dynamic recrystallization mechanism. Tested in the different conditions, the tensile strengths of the Mg-10Sn alloys extruded at the high working temperature are remarkably better than those of the other studied alloys. This significant improvement in tensile properties is mainly due to the particle strengthening and texture strengthening resulted from the more and finer primary dispersed particles and stronger texture, respectively.
文摘Microstructure of as-cast and extruded Mg-8Li-1Al-1Y alloy specimens was analyzed with OM,SEM and XRD.Results show that as-cast specimens are composed of α phase(Mg),β phase(Li) and rod-like Al2Y compound.In the extruded specimens,the microstructure is refined and the β phase has the effect of coordination during deformation.After extruding process,the Al2Y compound distributes evenly in the extruding direction.The results of mechanical properties tests show that the strength and elongation are both improved after extruding deformation.
基金supported by the National Research Foundation of Korea (NRF) grant funded by the Ministry of Science, ICT and Future Planning (MSIP, South Korea) (No.2019R1A2C1085272)by the Materials and Components Technology Development Program of the Ministry of Trade, Industry and Energy (MOTIE, South Korea) (No. 20011091)。
文摘Through an investigation of the microstructure and mechanical properties of extruded Mg–5Bi–x Sn(BT5x, x = 0, 2, 4, and 6 wt%) alloys,this study demonstrates that the addition of Sn to an Mg–5Bi binary alloy significantly improves the tensile strength of the extruded alloy.All the extruded alloys exhibit a typical basal fiber texture and a partially dynamically recrystallized(DRXed) microstructure consisting of fine DRXed grains and coarse un DRXed grains. As the Sn content increases from 0 wt% to 6 wt%, the average size of the DRXed grains decreases from 4.2 to 2.8 μm owing to the increase in the amount of precipitates via their grain-boundary pinning effect. The extruded B5 and BT52 alloys contain numerous Mg_(3)Bi_(2) precipitates, but their size and number density are smaller and higher, respectively, in the latter alloy.Numerous Mg_(2)Sn precipitates as well as Mg_(3)Bi_(2)precipitates are present in the extruded BT54 and BT56 alloys, and the number density of the Mg_(2)Sn precipitates is higher in the latter alloy because of its higher Sn content. The addition of 2 wt% Sn to the B5 alloy significantly improves the yield strength(YS) and ultimate tensile strength(UTS) of the extruded alloy—by 76 and 57 MPa, respectively. This drastic improvement is the combined outcome of enhanced grain-boundary hardening, precipitation hardening, and solid-solution hardening effects induced by the refined DRXed grains, numerous precipitates, and Sn solute atoms, respectively. The further addition of 2 wt% or 4 wt% Sn to the BT52 alloy leads to moderate increments in the YS and UTS of the extruded alloy. Specifically, each addition of 2 wt% Sn increases the YS and UTS by ~26 and ~20 MPa, respectively, which is attributed mainly to the additional precipitation hardening effect induced by the Mg_(2)Sn precipitates.
基金Project supported by Natural Science Foundation of Inner Mongolia,China(2015BS0512)
文摘The microstructure of as-cast and extruded Mg-14 Li-1 Al-(0, 0.3) La alloys was examined with XRD,OM, SEM, and EDS. The mechanical properties of the extruded specimens with and without La were compared. The results show that La addition has an obvious effect on the microstructure of the as-cast LA141 alloy by reducing the average grain size from 600 to 220 μm. β-Li and LiMgAl2 phases are observed in both alloys, and long-rod-shaped Al2 La phase is also observed in the La containing alloy. After extrusion, Al2 La phases are short-rod-shaped and distribute evenly in the alloy. LAl41-0.3 La alloy has higher elongation(34%), which is attributed to refined microstructure and weak texture due to shortrod-like Al2 La phase.
基金supported by National Natural Science Foundation of China(Nos.51771115,51775334 and 51821001)Joint Fund for Space Science and Technology(Nos.6141B06310106 and 6141B06300401)National Defense Science and Technology Innovation Special Zone Project(No.002-002-01)。
文摘In this study,the tensile and high-cycle fatigue properties of as-cast,solid solution treated and as-extruded Mg-8Li-3Al-2Zn-0.5Y alloy are investigated.The results show that the yield strength and ultimate tensile strength of as-cast alloy is 198.1 MPa and 222.5 MPa,which are improved to 274.7 MPa and 321.7 MPa,282.4 MPa and 319.3 MPa after solid solution and extrusion treatment,respectively.The high-cycle fatigue strength(at 10^(7)cycles,R=-1)of as-cast studied alloy is 65 MPa,which is improved to 90 MPa and 105 MPa after solid solution and extrusion treatment,respectively.The improvement of fatigue property of the solid solution treated alloy is mainly due to the lattice distortion caused by solid solution hindering the crack propagation.However,the improvement of fatigue property of the as-extruded alloy is mainly due to that the refined grains,stacked dislocations and dispersed secondary particles impede the crack propagation.
基金National Natural Science Foundation of China(51404166,51301118)Shanxi Province Science Foundation for Youths(2013021013-4)+1 种基金Advanced Programs of Department of Human Resources and Social Security of Shanxi Province for Returned ScholarsShanxi Scholarship Council of China(2014-023)