为研究Mg-Gd-Er-Zn稀土变形镁合金微观组织与力学性能,通过金属模铸造、固溶处理、热挤压和时效处理工艺过程,制备了Mg-Gd-Er-Zn稀土变形镁合金,并利用金相显微镜(optical microscopy,OM)、X射线衍射仪(Xray diffraction,XRD)、扫描电镜...为研究Mg-Gd-Er-Zn稀土变形镁合金微观组织与力学性能,通过金属模铸造、固溶处理、热挤压和时效处理工艺过程,制备了Mg-Gd-Er-Zn稀土变形镁合金,并利用金相显微镜(optical microscopy,OM)、X射线衍射仪(Xray diffraction,XRD)、扫描电镜(scanning electron microscopy,SEM)及透射电镜(transmission electron microscopy,TEM)等手段进行表征.结果表明:Mg-Gd-Er-Zn合金的铸态组织主要由α-Mg基体和沿晶界分布的(Mg,Zn)3Gd第2相组成,固溶后生成层片状的长周期堆垛有序(long period stacking ordered,LPSO)结构;经过热挤压变形,合金的晶粒得到显著细化;时效处理过程中,合金中析出纳米级尺寸的β'相.最终时效态合金的室温抗拉强度、屈服强度和伸长率可分别达397.5 MPa、359.0 MPa和6.0%.展开更多
The effects of homogenization and isothermal aging treatment on the mechanical properties of Mg-12Gd- 2Er-1Zn-0.6Zr （wt%） alloy were investigated. The precipitated long-period stacking order （LPSO） structure and t...The effects of homogenization and isothermal aging treatment on the mechanical properties of Mg-12Gd- 2Er-1Zn-0.6Zr （wt%） alloy were investigated. The precipitated long-period stacking order （LPSO） structure and the aging precipitation sequence of the conditioned alloys were observed and analyzed, respectively. The results indicate that the 14H-LPSO structure occurs after the homogenization treatment and the 131 phase forms after the isothermal aging process. These two independent processes could be controlled by the precipitation temperature range. The significant increase in the elongation of the as-cast alloy after homogenization treatment is attributed to the disappearance of the coarse primary Mgs（Gd, Er, Zn） phase and the presence of the 14H-LPSO structure. The precipitation sequence of the investigated alloy is α-Mg（SSS）/β″（D019）/β′（cbco）/β. Furthermore, the yield tensile strength （YTS） and ultimate tensile strength （UTS） values of the isothermal aging alloy have a great improvement, which could be attributed to the high density of the precipitated β′ phase.展开更多
The precipitation of the Mg-8Gd-2Er （wt.%） alloy at 200 ℃ was investigated by transmission electron microscopy （TEM） and X-ray diffraction （XRD）. The precipitation sequence was described as supersaturated solid...The precipitation of the Mg-8Gd-2Er （wt.%） alloy at 200 ℃ was investigated by transmission electron microscopy （TEM） and X-ray diffraction （XRD）. The precipitation sequence was described as supersaturated solid solution （S.S.S.S., cph）→β（D019）→β（bco）→ β-phase（fcc）, which was different from previously reported four stages sequence： （S.S.S.S., cph）→β（DO19）→β（bco）→β（fcc）→β-phase（fcc）. The morphologies and crystal structures of both β＇ and,β precipitates in the alloy were studied in the present investigation. The orientation relationship between the precipitate phases and the α-matrix was observed. The ultimate tensile strength （UTS） and tensile yield strength （TYS） of the as-cast alloy were 189 and 110 MPa, respectively, and the UTS and the YTS were improved greatly after ageing treatment. The values of UTS and YTS after peak ageing process were 308 and 246 MPa, respectively. The improved mechanical properties were mainly ascribed to the formation of β phase. The age hardening response decreased with increasing ageing time because the β phase got coarse as ageing time increased.展开更多
The microstructures of as-cast and as-solution Mg–12Gd–2Er–1Zn–0.6Zr alloys were investigated by optical microscopy（OM）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, highresoluti...The microstructures of as-cast and as-solution Mg–12Gd–2Er–1Zn–0.6Zr alloys were investigated by optical microscopy（OM）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, highresolution transmission electron microscopy（HRTEM）X-ray diffraction（XRD） and selected-area electron diffraction（SAED） in the present investigation. The results show that the primary eutectic phase Mg5（Gd, Er, Zn） and some flocculent features are found in the as-cast alloy; the SAED pattern indicates that these flocculent features are the dense areas of stacking faults. The 14H-LPSO structure precipitates in the temperature range of 673–793 K, and the volume fraction of 14H-LPSO structure increases with the extension of heating time; however, there is no precipitation of 14H-LPSO structure when the temperature reaches up to 803 K. In addition, the Mg5（Gd, Er, Zn） phase dissolves gradually along with the precipitation of 14H-LPSO structure.展开更多
文摘为研究Mg-Gd-Er-Zn稀土变形镁合金微观组织与力学性能,通过金属模铸造、固溶处理、热挤压和时效处理工艺过程,制备了Mg-Gd-Er-Zn稀土变形镁合金,并利用金相显微镜(optical microscopy,OM)、X射线衍射仪(Xray diffraction,XRD)、扫描电镜(scanning electron microscopy,SEM)及透射电镜(transmission electron microscopy,TEM)等手段进行表征.结果表明:Mg-Gd-Er-Zn合金的铸态组织主要由α-Mg基体和沿晶界分布的(Mg,Zn)3Gd第2相组成,固溶后生成层片状的长周期堆垛有序(long period stacking ordered,LPSO)结构;经过热挤压变形,合金的晶粒得到显著细化;时效处理过程中,合金中析出纳米级尺寸的β'相.最终时效态合金的室温抗拉强度、屈服强度和伸长率可分别达397.5 MPa、359.0 MPa和6.0%.
基金Projects(2011BAE22B01,2011BAE22B04-2) supported by the National Key Technology R&D Program during the 12th Five-Year PeriodProjects(51071004,51101002) supported by the National Natural Science Foundation of China
基金financially supported by Beijing Natural Science Foundation(No.2142005)the National Natural Science Foundation of China(No.51401005)the Ri Xin Talents Plan of Beijing University of Technology(Nos.2014-RX-L07 and2015-RX-L11)
文摘The effects of homogenization and isothermal aging treatment on the mechanical properties of Mg-12Gd- 2Er-1Zn-0.6Zr （wt%） alloy were investigated. The precipitated long-period stacking order （LPSO） structure and the aging precipitation sequence of the conditioned alloys were observed and analyzed, respectively. The results indicate that the 14H-LPSO structure occurs after the homogenization treatment and the 131 phase forms after the isothermal aging process. These two independent processes could be controlled by the precipitation temperature range. The significant increase in the elongation of the as-cast alloy after homogenization treatment is attributed to the disappearance of the coarse primary Mgs（Gd, Er, Zn） phase and the presence of the 14H-LPSO structure. The precipitation sequence of the investigated alloy is α-Mg（SSS）/β″（D019）/β′（cbco）/β. Furthermore, the yield tensile strength （YTS） and ultimate tensile strength （UTS） values of the isothermal aging alloy have a great improvement, which could be attributed to the high density of the precipitated β′ phase.
基金supported by National Key Basic Research Program (2007CB613706)National Science and Technology Supporting Plan of the Twelve Five-year (2011BAE22B04-2)+1 种基金National Natural Science Foundation of China (51071004)the Innovation Project for Talents (PHR200906101)
文摘The precipitation of the Mg-8Gd-2Er （wt.%） alloy at 200 ℃ was investigated by transmission electron microscopy （TEM） and X-ray diffraction （XRD）. The precipitation sequence was described as supersaturated solid solution （S.S.S.S., cph）→β（D019）→β（bco）→ β-phase（fcc）, which was different from previously reported four stages sequence： （S.S.S.S., cph）→β（DO19）→β（bco）→β（fcc）→β-phase（fcc）. The morphologies and crystal structures of both β＇ and,β precipitates in the alloy were studied in the present investigation. The orientation relationship between the precipitate phases and the α-matrix was observed. The ultimate tensile strength （UTS） and tensile yield strength （TYS） of the as-cast alloy were 189 and 110 MPa, respectively, and the UTS and the YTS were improved greatly after ageing treatment. The values of UTS and YTS after peak ageing process were 308 and 246 MPa, respectively. The improved mechanical properties were mainly ascribed to the formation of β phase. The age hardening response decreased with increasing ageing time because the β phase got coarse as ageing time increased.
基金financially supported by the Projects of Beijing Municipal Science and Technology Commission (No. Z131100003213019)the Projects of Beijing Municipal Commission of Education (Nos. KM201110005001 and KM201310005001)Beijing Natural Science Foundation (No. 2144043)
文摘The microstructures of as-cast and as-solution Mg–12Gd–2Er–1Zn–0.6Zr alloys were investigated by optical microscopy（OM）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, highresolution transmission electron microscopy（HRTEM）X-ray diffraction（XRD） and selected-area electron diffraction（SAED） in the present investigation. The results show that the primary eutectic phase Mg5（Gd, Er, Zn） and some flocculent features are found in the as-cast alloy; the SAED pattern indicates that these flocculent features are the dense areas of stacking faults. The 14H-LPSO structure precipitates in the temperature range of 673–793 K, and the volume fraction of 14H-LPSO structure increases with the extension of heating time; however, there is no precipitation of 14H-LPSO structure when the temperature reaches up to 803 K. In addition, the Mg5（Gd, Er, Zn） phase dissolves gradually along with the precipitation of 14H-LPSO structure.
