The electrochemical behavior of Yb3+ and electrodeposition of Mg-Yb alloy film at solid magnesium cathode in the molten LiCl-KCl-YbCl3(2 wt.%) system at 773 K was investigated.Transient electrochemical techniques,such...The electrochemical behavior of Yb3+ and electrodeposition of Mg-Yb alloy film at solid magnesium cathode in the molten LiCl-KCl-YbCl3(2 wt.%) system at 773 K was investigated.Transient electrochemical techniques,such as cyclic voltammetry,chronopotentiometry and chronoamperometry were used in order to explore the deposition mechanism of Yb.The reduction process of Yb3+ is stepwise reactions which are single-electron and double-electron reversible charge transfer reactions.The speed control step was a diffu...展开更多
Mechanical properties and biocorrosion behaviors in simulated body fluid(SBF)of newly developed Mg-5.8 Zn-0.5 Zr-x Yb(ZK60-X Yb,x=0,1.0,2.0wt%)magnesium alloys in the solution-treated(T4)and artificially-aged(T6)condi...Mechanical properties and biocorrosion behaviors in simulated body fluid(SBF)of newly developed Mg-5.8 Zn-0.5 Zr-x Yb(ZK60-X Yb,x=0,1.0,2.0wt%)magnesium alloys in the solution-treated(T4)and artificially-aged(T6)conditions were investigated.The results of mechanical properties show that with Yb addition,the microhardness and the ultimate tensile strength(UTS)of the tested alloys are significantly increased despite a slight decrease in tensile elongation in both T4 and T6 conditions.Especially,after the T6 treatment,the microhardness and the UTS of the samples were further improved,which was mainly attributed to the precipitation strengthening.The biocorrosion behaviors of the tested alloys were studied using electrochemical examinations and immersion tests.The results indicate that the biocorrosion resistance of the tested alloys is significantly improved by Yb addition in both T4 and T6 conditions.Although the corrosion resistance was slightly deteriorated after T6 treatment,the aged ZK60-2.0 Yb alloy still exhibited a favorable corrosion behavior,which was mainly ascribed to the corrosion barrier effect of a more compact and uniform protective film induced by the dispersed nano-scale precipitates.Electrochemical measurements also confirmed these observations.Given the favorable comprehensive performance in mechanical and biocorrosion behaviors,the T6 treated ZK60-2.0 Yb alloy may be considered as a promising candidate for biomedical applications.展开更多
The modification effects of ytterbium(Yb), Na_3PO_4 and Yb + Na_3PO_4 on primary Mg_2Si phase in Mg-4Si alloys were investigated by means of X-ray diffraction(XRD), optical microscopy(OM), scanning electron microscopy...The modification effects of ytterbium(Yb), Na_3PO_4 and Yb + Na_3PO_4 on primary Mg_2Si phase in Mg-4Si alloys were investigated by means of X-ray diffraction(XRD), optical microscopy(OM), scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS) analysis in this work. The results indicate that the morphology of the primary Mg_2Si phase apparently changes from coarse dendrites to fine dispersive polygonal particles and the mean size decreases from 276.6 μm to 7.1 μm, with combined modification of 0.8wt.% Yb and 2.64 wt.% Na_3PO_4. Such a morphological evolution results in improvement in the ultimate tensile strength and elongation of the alloys as compared to the base alloy. This may be attributed to the formation of the YbP particles that acted as the heterogeneous nucleation substrates for the primary Mg_2Si particles, resulting in a refined distribution of these precipitates. The results of XRD examination show that there was no reaction between Si and Yb or Na_3PO_4. Solo addition of Yb or Na_3PO_4 into the melt has no real modification effect on the microstructure, but the primary Mg_2Si particles and α-Mg phases become coarser than that in the unmodified alloy.展开更多
The dry sliding wear behavior of extruded Mg-9Sn and Mg-9Sn-3Yb alloys through pin-on-disc configuration was investigated at room temperature. Coefficient of friction, wear rate and wear resistance of extruded Mg-9Sn ...The dry sliding wear behavior of extruded Mg-9Sn and Mg-9Sn-3Yb alloys through pin-on-disc configuration was investigated at room temperature. Coefficient of friction, wear rate and wear resistance of extruded Mg-9Sn and Mg-9Sn-3Yb alloys were measured within a load range of 20-240 N and 20-380 N at a sliding velocity of 0.785 m/s, respectively. The wear tracks, worn surface and wear edge were observed using a scanning electron microscope and an energy dispersive X-ray spectrometer. The results indicated that wear rate, coefficient of friction and wear resistance changed with increasing applied load due to different wear mechanisms. Six wear mechanisms, namely adhesion, abrasion, oxidation, delamination, thermal softening and melting, were observed for both extruded alloys. The extruded Mg-9Sn-3Yb alloy exhibited good wear resistance compared with extruded Mg-9Sn alloy, which was mainly attributed to a large number of volume fraction of Mg2 Sn particles, the formation of thermal stable Mg2（Sn,Yb） particles and good elevated temperature mechanical properties.展开更多
Strain-hardening and warm deformation behaviors of extruded Mg-2Sn-0.5Yb alloy(at.%)sheet were investigated in uniaxial tensile test at temperatures of 25-250 ℃ and strain rates of 1×10^(−3) s^(−1)-0.1 s^(−1).Th...Strain-hardening and warm deformation behaviors of extruded Mg-2Sn-0.5Yb alloy(at.%)sheet were investigated in uniaxial tensile test at temperatures of 25-250 ℃ and strain rates of 1×10^(−3) s^(−1)-0.1 s^(−1).The data fit with the Kocks-Mecking type plots were used to show different stages of strain hardening.Besides III-stage and IV-stage,the absence of the II-stage strain hardening at room temperature should be related to the sufficient dynamic recrystallization during extrusion.The decrease of strain hardening ability of the alloy after yielding was attributed to the reduction of dislocation density with increasing testing temperature.Strain rate sensitivity(SRS)was significantly enhanced with increasing temperature,and the corresponding m-value was calculated as 0.07-0.12,which indicated that the deformation mechanism was dominated by the climb-controlled dislocation creep at 200 ℃.Furthermore,the grain boundary sliding(GBS)was activated at 250 ℃,which contributed to the higher SRS.The activation energy was calculated as 213.67 kJ mol^(−1),which was higher than that of lattice diffusion or grain boundary self-diffusion.In addition,the alloy exhibited a quasi superplasticity at 250 ℃ with a strain rate of 1×10^(−3) s^(−1),which was mainly related to the fine microstructure and the presence of the Mg2Sn and Mg2(Sn,Yb)particles.展开更多
Microstructures and mechanical properties of extruded Mg-2Sn-xYb(x=0,0.1,0.5 at.%)sheets were investigated.The grain size of as-cast Mg-2Sn alloy is significantly reduced with increasing Yb concentration.In addition t...Microstructures and mechanical properties of extruded Mg-2Sn-xYb(x=0,0.1,0.5 at.%)sheets were investigated.The grain size of as-cast Mg-2Sn alloy is significantly reduced with increasing Yb concentration.In addition toα-Mg and Mg_(2)Sn phase,some fine Mg_(2)(Sn,Yb)particles are observed in as-cast Mg-2Sn-0.5Yb alloy,but these fine particles are not observed in as-cast Mg-2Sn-0.1Yb alloy due to a high solubility of Yb in Mg matrix.Tensile tests demonstrated that extruded Mg-2Sn-0.5Yb sheet exhibited the highest tensile strength and available elongation to failure at room temperature,while extruded Mg-2Sn-0.1Yb alloy exhibited the highest tensile properties at 100°C and 200°C.The difference in the tensile properties of extruded sheets mainly arises from the different strengthening roles of grain refinement,solid solution strengthening and precipitation strengthening of particles.展开更多
This paper presented a novel study on electrochemical codeposition of Mg-Li-Yb alloys in LiCl-KCl-KF-MgCl2-Yb2O3 melts on molybdenum. The factors of the current efficiency were investigated. Electrolysis temperature h...This paper presented a novel study on electrochemical codeposition of Mg-Li-Yb alloys in LiCl-KCl-KF-MgCl2-Yb2O3 melts on molybdenum. The factors of the current efficiency were investigated. Electrolysis temperature had great influence on current efficiency; the highest current efficiency was obtained when electrolysis temperature was about 660 oC. The content of Li in Mg-Li-Yb alloys increased with the high current densities. The optimal electrolytic temperature and cathodic current density were around 660 oC and 9.3 A/cm2, respectively. The chemical content, phases, morphology of the alloys and the distribution of the elements were analyzed by X-ray diffraction, scanning electron microscopy, inductively coupled plasma mass spectrometry, respectively. The intermetallic of Mg-Yb was mainly distributed in the grain boundary of the alloys, presented as reticulated structures, and refined the grains. The lithium and ytterbium contents in Mg-Li-Yb al-loys could be controlled by changing the concentration of MgCl2 and Yb2O3 and the electrolysis conditions.展开更多
基金supported by 863 Project of Ministry of Science and Technology of China (2006AA03Z510)the National Natural Science Foundation of China (50871033)+1 种基金the Scientific Technology Project of Heilongjiang Province (GC06A212)the fund from Harbin Municipal Science & Technology Bureau (2006PFXXG006)
文摘The electrochemical behavior of Yb3+ and electrodeposition of Mg-Yb alloy film at solid magnesium cathode in the molten LiCl-KCl-YbCl3(2 wt.%) system at 773 K was investigated.Transient electrochemical techniques,such as cyclic voltammetry,chronopotentiometry and chronoamperometry were used in order to explore the deposition mechanism of Yb.The reduction process of Yb3+ is stepwise reactions which are single-electron and double-electron reversible charge transfer reactions.The speed control step was a diffu...
基金This work was supported by the National Natural Science Foundation of China(grant number 51975484 and 51605392)Fundamental Research Funds for the Central Universities(grant number XDJK2020B001).
文摘Mechanical properties and biocorrosion behaviors in simulated body fluid(SBF)of newly developed Mg-5.8 Zn-0.5 Zr-x Yb(ZK60-X Yb,x=0,1.0,2.0wt%)magnesium alloys in the solution-treated(T4)and artificially-aged(T6)conditions were investigated.The results of mechanical properties show that with Yb addition,the microhardness and the ultimate tensile strength(UTS)of the tested alloys are significantly increased despite a slight decrease in tensile elongation in both T4 and T6 conditions.Especially,after the T6 treatment,the microhardness and the UTS of the samples were further improved,which was mainly attributed to the precipitation strengthening.The biocorrosion behaviors of the tested alloys were studied using electrochemical examinations and immersion tests.The results indicate that the biocorrosion resistance of the tested alloys is significantly improved by Yb addition in both T4 and T6 conditions.Although the corrosion resistance was slightly deteriorated after T6 treatment,the aged ZK60-2.0 Yb alloy still exhibited a favorable corrosion behavior,which was mainly ascribed to the corrosion barrier effect of a more compact and uniform protective film induced by the dispersed nano-scale precipitates.Electrochemical measurements also confirmed these observations.Given the favorable comprehensive performance in mechanical and biocorrosion behaviors,the T6 treated ZK60-2.0 Yb alloy may be considered as a promising candidate for biomedical applications.
基金financially supported by the Fundamental Research Funds for Central Universities(Grant No.:XDJK2015B001)
文摘The modification effects of ytterbium(Yb), Na_3PO_4 and Yb + Na_3PO_4 on primary Mg_2Si phase in Mg-4Si alloys were investigated by means of X-ray diffraction(XRD), optical microscopy(OM), scanning electron microscopy(SEM) and energy dispersive spectroscopy(EDS) analysis in this work. The results indicate that the morphology of the primary Mg_2Si phase apparently changes from coarse dendrites to fine dispersive polygonal particles and the mean size decreases from 276.6 μm to 7.1 μm, with combined modification of 0.8wt.% Yb and 2.64 wt.% Na_3PO_4. Such a morphological evolution results in improvement in the ultimate tensile strength and elongation of the alloys as compared to the base alloy. This may be attributed to the formation of the YbP particles that acted as the heterogeneous nucleation substrates for the primary Mg_2Si particles, resulting in a refined distribution of these precipitates. The results of XRD examination show that there was no reaction between Si and Yb or Na_3PO_4. Solo addition of Yb or Na_3PO_4 into the melt has no real modification effect on the microstructure, but the primary Mg_2Si particles and α-Mg phases become coarser than that in the unmodified alloy.
基金supported by the National Natural Science Foundation of China(51371089,51301082,51201158)
文摘The dry sliding wear behavior of extruded Mg-9Sn and Mg-9Sn-3Yb alloys through pin-on-disc configuration was investigated at room temperature. Coefficient of friction, wear rate and wear resistance of extruded Mg-9Sn and Mg-9Sn-3Yb alloys were measured within a load range of 20-240 N and 20-380 N at a sliding velocity of 0.785 m/s, respectively. The wear tracks, worn surface and wear edge were observed using a scanning electron microscope and an energy dispersive X-ray spectrometer. The results indicated that wear rate, coefficient of friction and wear resistance changed with increasing applied load due to different wear mechanisms. Six wear mechanisms, namely adhesion, abrasion, oxidation, delamination, thermal softening and melting, were observed for both extruded alloys. The extruded Mg-9Sn-3Yb alloy exhibited good wear resistance compared with extruded Mg-9Sn alloy, which was mainly attributed to a large number of volume fraction of Mg2 Sn particles, the formation of thermal stable Mg2（Sn,Yb） particles and good elevated temperature mechanical properties.
基金This work was financially supported by the National Nature Science Foundations of China(No.51371089 and No.51301082).
文摘Strain-hardening and warm deformation behaviors of extruded Mg-2Sn-0.5Yb alloy(at.%)sheet were investigated in uniaxial tensile test at temperatures of 25-250 ℃ and strain rates of 1×10^(−3) s^(−1)-0.1 s^(−1).The data fit with the Kocks-Mecking type plots were used to show different stages of strain hardening.Besides III-stage and IV-stage,the absence of the II-stage strain hardening at room temperature should be related to the sufficient dynamic recrystallization during extrusion.The decrease of strain hardening ability of the alloy after yielding was attributed to the reduction of dislocation density with increasing testing temperature.Strain rate sensitivity(SRS)was significantly enhanced with increasing temperature,and the corresponding m-value was calculated as 0.07-0.12,which indicated that the deformation mechanism was dominated by the climb-controlled dislocation creep at 200 ℃.Furthermore,the grain boundary sliding(GBS)was activated at 250 ℃,which contributed to the higher SRS.The activation energy was calculated as 213.67 kJ mol^(−1),which was higher than that of lattice diffusion or grain boundary self-diffusion.In addition,the alloy exhibited a quasi superplasticity at 250 ℃ with a strain rate of 1×10^(−3) s^(−1),which was mainly related to the fine microstructure and the presence of the Mg2Sn and Mg2(Sn,Yb)particles.
基金This work was financially supported by the National Natural Science Foundations of China(No.51371089,No.51301082 and No.51201068).
文摘Microstructures and mechanical properties of extruded Mg-2Sn-xYb(x=0,0.1,0.5 at.%)sheets were investigated.The grain size of as-cast Mg-2Sn alloy is significantly reduced with increasing Yb concentration.In addition toα-Mg and Mg_(2)Sn phase,some fine Mg_(2)(Sn,Yb)particles are observed in as-cast Mg-2Sn-0.5Yb alloy,but these fine particles are not observed in as-cast Mg-2Sn-0.1Yb alloy due to a high solubility of Yb in Mg matrix.Tensile tests demonstrated that extruded Mg-2Sn-0.5Yb sheet exhibited the highest tensile strength and available elongation to failure at room temperature,while extruded Mg-2Sn-0.1Yb alloy exhibited the highest tensile properties at 100°C and 200°C.The difference in the tensile properties of extruded sheets mainly arises from the different strengthening roles of grain refinement,solid solution strengthening and precipitation strengthening of particles.
基金Project supported by the National Natural Science Foundation of China (21103033, 21101040 and 21173060)the Fundamental Research funds for the Central Universities (HEUCF101210002)863 projects (2011AA03A409, 2009AA050702)
文摘This paper presented a novel study on electrochemical codeposition of Mg-Li-Yb alloys in LiCl-KCl-KF-MgCl2-Yb2O3 melts on molybdenum. The factors of the current efficiency were investigated. Electrolysis temperature had great influence on current efficiency; the highest current efficiency was obtained when electrolysis temperature was about 660 oC. The content of Li in Mg-Li-Yb alloys increased with the high current densities. The optimal electrolytic temperature and cathodic current density were around 660 oC and 9.3 A/cm2, respectively. The chemical content, phases, morphology of the alloys and the distribution of the elements were analyzed by X-ray diffraction, scanning electron microscopy, inductively coupled plasma mass spectrometry, respectively. The intermetallic of Mg-Yb was mainly distributed in the grain boundary of the alloys, presented as reticulated structures, and refined the grains. The lithium and ytterbium contents in Mg-Li-Yb al-loys could be controlled by changing the concentration of MgCl2 and Yb2O3 and the electrolysis conditions.
