This comprehensive review examines the structural,mechanical,electronic,and thermodynamic properties of Mg-Li-Al alloys,focusing on their corrosion resistance and mechanical performance enhancement.Utilizing first-pri...This comprehensive review examines the structural,mechanical,electronic,and thermodynamic properties of Mg-Li-Al alloys,focusing on their corrosion resistance and mechanical performance enhancement.Utilizing first-principles calculations based on Density Functional Theory(DFT)and the quasi-harmonic approximation(QHA),the combined properties of the Mg-Li-Al phase are explored,revealing superior incompressibility,shear resistance,and stiffness compared to individual elements.The review highlights the brittleness of the alloy,supported by B/G ratios,Cauchy pressures,and Poisson’s ratios.Electronic structure analysis shows metallic behavior with varied covalent bonding characteristics,while Mulliken population analysis emphasizes significant electron transfer within the alloy.This paper also studied thermodynamic properties,including Debye temperature,heat capacity,enthalpy,free energy,and entropy,which are precisely examined,highlighting the Mg-Li-Al phase sensitive to thermal conductivity and thermal performance potential.Phonon density of states(PHDOS)confirms dynamic stability,while anisotropic sound velocities reveal elastic anisotropies.This comprehensive review not only consolidates the current understanding of the Mg-Li-Al alloy’s properties but also proposes innovative strategies for enhancing corrosion resistance.Among these strategies is the introduction of a corrosion barrier akin to the Mg-Li-Al network,which holds promise for advancing both the applications and performance of these alloys.This review serves as a crucial foundation for future research aimed at optimizing alloy design and processing methods.展开更多
研究了 Mg L i4Al和 Mg L i8Al合金的阻尼性能。结果表明 ,Mg- L i- Al合金的阻尼性能随锂含量的增多和温度的提高而明显增高。其中 Mg L i8Al合金的室温阻尼性能达到 Q- 1 =0 .0 1的高阻尼值。Mg L i8Al合金的阻尼明显大于Mg L i4Al合...研究了 Mg L i4Al和 Mg L i8Al合金的阻尼性能。结果表明 ,Mg- L i- Al合金的阻尼性能随锂含量的增多和温度的提高而明显增高。其中 Mg L i8Al合金的室温阻尼性能达到 Q- 1 =0 .0 1的高阻尼值。Mg L i8Al合金的阻尼明显大于Mg L i4Al合金的阻尼是由于 Mg L展开更多
Mg-xLi-Al alloys with Mn addition from 0.2% to 1.5 % by wt. were produced and studied. The density of the alloys is very low, between 1.21 g/cm3 and 1.64 g/cm3, while the microstructures change from single α-, (α+β...Mg-xLi-Al alloys with Mn addition from 0.2% to 1.5 % by wt. were produced and studied. The density of the alloys is very low, between 1.21 g/cm3 and 1.64 g/cm3, while the microstructures change from single α-, (α+β)-, to single β-phase with lithium content rising from 5 % to 22 % by wt. The main alloy studied was LA92 alloy with Mn addition. The results of the tensile tests show that the strength decreases with increasing lithium content, while the elongation increases sharply, and the UTS and YS rise by 26.8% and 22.7% respectively, when 0.5 % by wt. Mn is added. It is also known, by microstructure observation, SEM with EDS and X-ray analysis, that adding Mn can produce some new hard phases in the alloy, which may worsen the tensile properties.展开更多
This work presents a study on electrochemical formation of Mg-Li-Al alloys on an inert electrode （Mo electrode） in a molten KCl-LiCl-AlC13-MgCI2-KF system. It aims at preparation Mg-Li-Al metal alloy directly under ...This work presents a study on electrochemical formation of Mg-Li-Al alloys on an inert electrode （Mo electrode） in a molten KCl-LiCl-AlC13-MgCI2-KF system. It aims at preparation Mg-Li-Al metal alloy directly under an optimal electrolytic parameters. Main factors which affect current efficiency are investigated. We have discussed the co-electrodeposition conditions and the effect of technical parameters on these experiments, and gained a good electrolytic process. The result of calculation shows that co-electrodeposition Mg, Li and A1 occurs at the cathode current density higher than 9 A/cm^2 and electrolytic voltage between 6 to 9 V. And at the optimal parameters, 12-13 A/cm^2, 620-640 ℃, the highest current efficiency reaches as high as 86%. Lithium combined with magnesium forms Li0.92Mg4.0s and LiaMg7, and aluminum mainly exists in a form of Mg0.58Al0.42, distributing in the alpha phases and beta phases.展开更多
A system study on aging behavior and the influence of heat treatment on mechanical property of Mg8LilAl and Mg11Li3Al alloys has been carried out. The results show that the alloys described above have apparent aging b...A system study on aging behavior and the influence of heat treatment on mechanical property of Mg8LilAl and Mg11Li3Al alloys has been carried out. The results show that the alloys described above have apparent aging behavior and over aging happens even at room temperature. θ (MgLi2Al) phase has been identified when hardness reaches aging peak. With the increase of aging temperature, the size of 8(MgLi2Al)phase becomes larger apparently and 0ver aging happens. Heat treatment can raise tensile strength of Mg8Li1Al and Mg11Li3Al alloys, but the elongation decreases greatly.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
In the present study,a response optimization method using Extreme Vertices Mixer Design(EVMD)approach is proposed for stress optimization in a thermomechanically processed Mg-Li-Al alloy.Experimentation was planned as...In the present study,a response optimization method using Extreme Vertices Mixer Design(EVMD)approach is proposed for stress optimization in a thermomechanically processed Mg-Li-Al alloy.Experimentation was planned as per mixed design proportions of Mg,Li and Al and process variables(i.e.temperature and strain rate).Each experiment has been performed under different conditions of factors proportions and process variables.The response,particularly stress has been considered for each experiment.The response is optimized to find an optimum condition when the contributing factors influence material characteristics in such a way,to achieve better strength,ductility and corrosion resistance.Estimated regression coefficient table for response has been observed to identify the important factors in this process and significantly high variance inflation factor has been observed.Most importantly,an optimum condition is achieved from this analysis which fulfills the experimental observations and theoretical assumptions.展开更多
The effects of external fields such as electromagnetic field on the structure and heat treatment behavior of Mg-Li-Al alloys were studied.Mg-8Li-3Al alloys cast with and without electromagnetic stirring were used for ...The effects of external fields such as electromagnetic field on the structure and heat treatment behavior of Mg-Li-Al alloys were studied.Mg-8Li-3Al alloys cast with and without electromagnetic stirring were used for solution treatment and aging treatment. Experimental results show that the dendritic arms are broken and a large quantity of equiaxed grains appear in the microstructure of specimens with electromagnetic stirring(EMS).With the increase of the quenching temperature(150-350℃),the solution of Mg and Al in solidβphase increases,and the Brinell hardness of the alloy increases as well.Aging peak and over aging happen becauseθ(MgLi_2Al) which precipitates in theβmatrix and strengthens the alloy is unstable and transforms to stable AlLi phase.Aging curves of EMS specimens change in a smaller amplitude.展开更多
文摘This comprehensive review examines the structural,mechanical,electronic,and thermodynamic properties of Mg-Li-Al alloys,focusing on their corrosion resistance and mechanical performance enhancement.Utilizing first-principles calculations based on Density Functional Theory(DFT)and the quasi-harmonic approximation(QHA),the combined properties of the Mg-Li-Al phase are explored,revealing superior incompressibility,shear resistance,and stiffness compared to individual elements.The review highlights the brittleness of the alloy,supported by B/G ratios,Cauchy pressures,and Poisson’s ratios.Electronic structure analysis shows metallic behavior with varied covalent bonding characteristics,while Mulliken population analysis emphasizes significant electron transfer within the alloy.This paper also studied thermodynamic properties,including Debye temperature,heat capacity,enthalpy,free energy,and entropy,which are precisely examined,highlighting the Mg-Li-Al phase sensitive to thermal conductivity and thermal performance potential.Phonon density of states(PHDOS)confirms dynamic stability,while anisotropic sound velocities reveal elastic anisotropies.This comprehensive review not only consolidates the current understanding of the Mg-Li-Al alloy’s properties but also proposes innovative strategies for enhancing corrosion resistance.Among these strategies is the introduction of a corrosion barrier akin to the Mg-Li-Al network,which holds promise for advancing both the applications and performance of these alloys.This review serves as a crucial foundation for future research aimed at optimizing alloy design and processing methods.
文摘研究了 Mg L i4Al和 Mg L i8Al合金的阻尼性能。结果表明 ,Mg- L i- Al合金的阻尼性能随锂含量的增多和温度的提高而明显增高。其中 Mg L i8Al合金的室温阻尼性能达到 Q- 1 =0 .0 1的高阻尼值。Mg L i8Al合金的阻尼明显大于Mg L i4Al合金的阻尼是由于 Mg L
文摘Mg-xLi-Al alloys with Mn addition from 0.2% to 1.5 % by wt. were produced and studied. The density of the alloys is very low, between 1.21 g/cm3 and 1.64 g/cm3, while the microstructures change from single α-, (α+β)-, to single β-phase with lithium content rising from 5 % to 22 % by wt. The main alloy studied was LA92 alloy with Mn addition. The results of the tensile tests show that the strength decreases with increasing lithium content, while the elongation increases sharply, and the UTS and YS rise by 26.8% and 22.7% respectively, when 0.5 % by wt. Mn is added. It is also known, by microstructure observation, SEM with EDS and X-ray analysis, that adding Mn can produce some new hard phases in the alloy, which may worsen the tensile properties.
基金supported by National High Technical Research and Development Programme of China (No.2006AA03Z510)the National Natural Science Foundation of China (No.50871033)the Scientific Technology Bureau of Harbin(No.2009RFLXG012)
文摘This work presents a study on electrochemical formation of Mg-Li-Al alloys on an inert electrode （Mo electrode） in a molten KCl-LiCl-AlC13-MgCI2-KF system. It aims at preparation Mg-Li-Al metal alloy directly under an optimal electrolytic parameters. Main factors which affect current efficiency are investigated. We have discussed the co-electrodeposition conditions and the effect of technical parameters on these experiments, and gained a good electrolytic process. The result of calculation shows that co-electrodeposition Mg, Li and A1 occurs at the cathode current density higher than 9 A/cm^2 and electrolytic voltage between 6 to 9 V. And at the optimal parameters, 12-13 A/cm^2, 620-640 ℃, the highest current efficiency reaches as high as 86%. Lithium combined with magnesium forms Li0.92Mg4.0s and LiaMg7, and aluminum mainly exists in a form of Mg0.58Al0.42, distributing in the alpha phases and beta phases.
文摘A system study on aging behavior and the influence of heat treatment on mechanical property of Mg8LilAl and Mg11Li3Al alloys has been carried out. The results show that the alloys described above have apparent aging behavior and over aging happens even at room temperature. θ (MgLi2Al) phase has been identified when hardness reaches aging peak. With the increase of aging temperature, the size of 8(MgLi2Al)phase becomes larger apparently and 0ver aging happens. Heat treatment can raise tensile strength of Mg8Li1Al and Mg11Li3Al alloys, but the elongation decreases greatly.
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.
文摘In the present study,a response optimization method using Extreme Vertices Mixer Design(EVMD)approach is proposed for stress optimization in a thermomechanically processed Mg-Li-Al alloy.Experimentation was planned as per mixed design proportions of Mg,Li and Al and process variables(i.e.temperature and strain rate).Each experiment has been performed under different conditions of factors proportions and process variables.The response,particularly stress has been considered for each experiment.The response is optimized to find an optimum condition when the contributing factors influence material characteristics in such a way,to achieve better strength,ductility and corrosion resistance.Estimated regression coefficient table for response has been observed to identify the important factors in this process and significantly high variance inflation factor has been observed.Most importantly,an optimum condition is achieved from this analysis which fulfills the experimental observations and theoretical assumptions.
基金Project(107031)supported by the Key Grant of Science & Technology of the Ministry of Education of China
文摘The effects of external fields such as electromagnetic field on the structure and heat treatment behavior of Mg-Li-Al alloys were studied.Mg-8Li-3Al alloys cast with and without electromagnetic stirring were used for solution treatment and aging treatment. Experimental results show that the dendritic arms are broken and a large quantity of equiaxed grains appear in the microstructure of specimens with electromagnetic stirring(EMS).With the increase of the quenching temperature(150-350℃),the solution of Mg and Al in solidβphase increases,and the Brinell hardness of the alloy increases as well.Aging peak and over aging happen becauseθ(MgLi_2Al) which precipitates in theβmatrix and strengthens the alloy is unstable and transforms to stable AlLi phase.Aging curves of EMS specimens change in a smaller amplitude.
