An electrochemical approach for the preparation of Mg-Li-Y alloys via co-reduction of Mg, Li, and Y on a molybdenum electrode in LiCl-KCl-MgCl2-YCl3 melts at 943 K was investigated. Cyclic voltammograms （CVs） illumi...An electrochemical approach for the preparation of Mg-Li-Y alloys via co-reduction of Mg, Li, and Y on a molybdenum electrode in LiCl-KCl-MgCl2-YCl3 melts at 943 K was investigated. Cyclic voltammograms （CVs） illuminated that the underpotential deposition （UPD） of yttrium on pre-deposited magnesium led to the formation of a liquid Mg-Y alloy, and the succeeding underpotential deposition of lithium on pre-deposited Mg-Y led to the formation of a liquid Mg-Li-Y alloy. Chronopotentiometry measurements indicated that the order of electrode reactions was as follows： discharge of Mg（II） to Mg-metal, electroreduction of Y on the surface of Mg with formation of ε-Mg24＋xY5 and after that the discharge of Li＋ with the deposition of Mg-Li-Y alloys. X-ray diffraction （XRD） indicated that Mg-Li-Y alloys with different phases were formed via galvanostatic electrolysis. The microstructure of different phases of Mg-Li-Y alloys was characterized by optical microscope （OM） and scanning electron microscopy （SEM）. The analysis results of inductively coupled plasma atomic emission spectrometer （ICP-AES） showed that the chemical compositions of Mg-Li-Y alloys corresponded with the phase structures of the XRD patterns, and the lithium and yttrium contents of Mg-Li-Y alloys depended on the concentrations of MgCl2 and YCl3 .展开更多
Mg-6Li and Mg-6Li-1Y （wt.%） alloys were prepared using permanent model casting method, and microstructure and mechanical properties were investigated by means of X-ray diffraction （XRD）, scanning electron microsco...Mg-6Li and Mg-6Li-1Y （wt.%） alloys were prepared using permanent model casting method, and microstructure and mechanical properties were investigated by means of X-ray diffraction （XRD）, scanning electron microscopy （SEM）, optical microscopy （OM）, energy dis-persive spectrometry （EDS）, transmission electron microscopy （TEM）, etc. The results showed that α-Mg and ？-Li phases existed in both al-loys, and there was also Y-enriched phase in Mg-6Li-1Y alloy. The composition of Y-enriched phase was near to the maximal solid solubility of Y in α-Mg phase. The ultimate tensile strength and yield strength of Mg-6Li-1Y alloy were improved to 112 and 107 MPa, respectively. The elongation of Mg-6Li-1Y alloy was greatly enhanced to 32% at room temperature, which was about eight times as great as that of Mg-6Li alloy. The strengthening effects of Mg-6Li-1Y alloy were attributed to the solid solution effect and precipitates both introduced by Y.展开更多
To control the superplastic flow and fracture and examine the variation in deformation energy,the stress and grain size of Mg-7.28Li-2.19Al-0.091Y alloy were obtained using tensile testing and microstructure quantific...To control the superplastic flow and fracture and examine the variation in deformation energy,the stress and grain size of Mg-7.28Li-2.19Al-0.091Y alloy were obtained using tensile testing and microstructure quantification,and new high temperature deformation energy models were established.Results show that the grain interior deformation energy increases with increasing the strain rate and decreases with increasing the temperature.The variation in the grain boundary deformation energy is opposite to that in the grain interior deformation energy.At a given temperature,critical cavity nucleation energy decreases with increasing strain rate and cavity nucleation becomes easy,whereas at a given strain rate,critical cavity nucleation energy increases with increasing temperature and cavity nucleation becomes difficult.The newly established models of the critical cavity nucleation radius and energy provide a way for predicting the initiation of microcrack and improving the service life of the forming parts.展开更多
To obtain magnesium alloys with a low density and improved mechanical properties,Y element was added into Mg−4Li−3Al(wt.%)alloys,and the effect of Y content on microstructure evolution and mechanical properties was in...To obtain magnesium alloys with a low density and improved mechanical properties,Y element was added into Mg−4Li−3Al(wt.%)alloys,and the effect of Y content on microstructure evolution and mechanical properties was investigated by using optical microscopy,scanning electron microscopy and tensile tests.The results show that mechanical properties of as-cast Mg−4Li−3Al alloys with Y addition are significantly improved as a result of hot extrusion.The best comprehensive mechanical properties are obtained in hot-extruded Mg−4Li−3Al−1.5Y alloy,which possesses high ultimate tensile strength(UTS=248 MPa)and elongation(δ=27%).The improvement of mechanical properties of hot-extruded Mg−4Li−3Al−1.5Y alloy was mainly attributed to combined effects of grain refinement,solid solution strengthening and precipitation strengthening.展开更多
基金Project supported by the National 863 Project of the Ministry of Science and Technology of China (2011AA03A409)National Natural Science Foundation of China (21103033, 21101040 and 91226201)+3 种基金the Fundamental Research Funds for the Central Universities (HEUCF201210002)the Basic Research Foundation of Harbin Engineering University of China (HEUFT08030)the Heilongjiang Postdoctoral Fund (LBH-Z10196 and LBH-Z10207)the China Postdoctoral Science Foundation (20100480974)
文摘An electrochemical approach for the preparation of Mg-Li-Y alloys via co-reduction of Mg, Li, and Y on a molybdenum electrode in LiCl-KCl-MgCl2-YCl3 melts at 943 K was investigated. Cyclic voltammograms （CVs） illuminated that the underpotential deposition （UPD） of yttrium on pre-deposited magnesium led to the formation of a liquid Mg-Y alloy, and the succeeding underpotential deposition of lithium on pre-deposited Mg-Y led to the formation of a liquid Mg-Li-Y alloy. Chronopotentiometry measurements indicated that the order of electrode reactions was as follows： discharge of Mg（II） to Mg-metal, electroreduction of Y on the surface of Mg with formation of ε-Mg24＋xY5 and after that the discharge of Li＋ with the deposition of Mg-Li-Y alloys. X-ray diffraction （XRD） indicated that Mg-Li-Y alloys with different phases were formed via galvanostatic electrolysis. The microstructure of different phases of Mg-Li-Y alloys was characterized by optical microscope （OM） and scanning electron microscopy （SEM）. The analysis results of inductively coupled plasma atomic emission spectrometer （ICP-AES） showed that the chemical compositions of Mg-Li-Y alloys corresponded with the phase structures of the XRD patterns, and the lithium and yttrium contents of Mg-Li-Y alloys depended on the concentrations of MgCl2 and YCl3 .
基金supported by the National Natural Science Foundation of China for Creative Research Group (20921002)the Foundation for Science Program of Changchun City (08YJ09)
文摘Mg-6Li and Mg-6Li-1Y （wt.%） alloys were prepared using permanent model casting method, and microstructure and mechanical properties were investigated by means of X-ray diffraction （XRD）, scanning electron microscopy （SEM）, optical microscopy （OM）, energy dis-persive spectrometry （EDS）, transmission electron microscopy （TEM）, etc. The results showed that α-Mg and ？-Li phases existed in both al-loys, and there was also Y-enriched phase in Mg-6Li-1Y alloy. The composition of Y-enriched phase was near to the maximal solid solubility of Y in α-Mg phase. The ultimate tensile strength and yield strength of Mg-6Li-1Y alloy were improved to 112 and 107 MPa, respectively. The elongation of Mg-6Li-1Y alloy was greatly enhanced to 32% at room temperature, which was about eight times as great as that of Mg-6Li alloy. The strengthening effects of Mg-6Li-1Y alloy were attributed to the solid solution effect and precipitates both introduced by Y.
基金Project(51334006)supported by the National Natural Science Foundation of China
文摘To control the superplastic flow and fracture and examine the variation in deformation energy,the stress and grain size of Mg-7.28Li-2.19Al-0.091Y alloy were obtained using tensile testing and microstructure quantification,and new high temperature deformation energy models were established.Results show that the grain interior deformation energy increases with increasing the strain rate and decreases with increasing the temperature.The variation in the grain boundary deformation energy is opposite to that in the grain interior deformation energy.At a given temperature,critical cavity nucleation energy decreases with increasing strain rate and cavity nucleation becomes easy,whereas at a given strain rate,critical cavity nucleation energy increases with increasing temperature and cavity nucleation becomes difficult.The newly established models of the critical cavity nucleation radius and energy provide a way for predicting the initiation of microcrack and improving the service life of the forming parts.
基金The work was supported by the National Natural Science Foundation of China(No.51401115)the Promoted Research Fund for Excellent Young and Middle-aged Scientists of Shandong Province,China(No.BS2013CL034)partially by the Fundamental Research Funds of Shandong University,China(2016JC016).
文摘To obtain magnesium alloys with a low density and improved mechanical properties,Y element was added into Mg−4Li−3Al(wt.%)alloys,and the effect of Y content on microstructure evolution and mechanical properties was investigated by using optical microscopy,scanning electron microscopy and tensile tests.The results show that mechanical properties of as-cast Mg−4Li−3Al alloys with Y addition are significantly improved as a result of hot extrusion.The best comprehensive mechanical properties are obtained in hot-extruded Mg−4Li−3Al−1.5Y alloy,which possesses high ultimate tensile strength(UTS=248 MPa)and elongation(δ=27%).The improvement of mechanical properties of hot-extruded Mg−4Li−3Al−1.5Y alloy was mainly attributed to combined effects of grain refinement,solid solution strengthening and precipitation strengthening.
