In this work,the aging response and mechanism of dual-phase Mg-Li-Al-Zn alloy at various temperatures are investigated.The results show that the strengthening after quenching is primarily attributed to the immediate p...In this work,the aging response and mechanism of dual-phase Mg-Li-Al-Zn alloy at various temperatures are investigated.The results show that the strengthening after quenching is primarily attributed to the immediate precipitation of the semi-coherent~Mg_(3)Zn phase.The aging softening of the studied alloy is mainly caused by the rapid transformation of the strengthening~Mg_(3)Zn phase to the softening MgLi(Al,Zn)phase,along with the coarsening of theα-Mg matrix and precipitates withinβ-Li matrix.Further analysis indicates that the quick precipitation and transformation of~Mg_(3)Zn is a consequence of the high diffusion rate of solute atoms,resulting from dense vacancy concentration in theβ-Li matrix.This research bridges a critical gap in the study of aging mechanism in the dual-phase Mg-Li-Al-Zn alloy,providing a theoretical basis for the development and application of high-performance and thermal-stable Mg-Li alloys.展开更多
Effects of electromagnetic stirring on the microstructure and mechanical properties of the magnesium-lithium-aluminum alloy were studied.The results reveal that,the morphology of theαphase changes from the long block...Effects of electromagnetic stirring on the microstructure and mechanical properties of the magnesium-lithium-aluminum alloy were studied.The results reveal that,the morphology of theαphase changes from the long block to globular structure andβ phase distributes more widely in the periphery ofαphase when the electromagnetic stirring voltage is higher than 110 V.The mechanical properties are increased significantly with the increasing electromagnetic stirring.The tensile strength is improved from 172 to 195 MPa,and the elongation is increased from 10.65%to 25.75%.展开更多
Annealing treatment is an effective strategy to enhance the comprehensive properties of Mg-8Li-3Al-2Zn(LAZ832)alloy,where the cooling rate plays a decisive role in tailoring microstructure and performance.This study s...Annealing treatment is an effective strategy to enhance the comprehensive properties of Mg-8Li-3Al-2Zn(LAZ832)alloy,where the cooling rate plays a decisive role in tailoring microstructure and performance.This study systematically investigates the effects of cooling rates,controlled via water quenching(WC),air cooling(AC),and furnace cooling(FC),on the phase evolution,mechanical properties,and corrosion resistance of LAZ832.The annealed microstructure consists ofα-Mg,β-Li,AlLi,and MgLi_(2)Al phases,and the volume fraction of Al-Li phases(AlLi and MgLi_(2)Al)increases as the cooling rate decreases.Strengthening mechanisms are dominated by solid solution strengthening,driven by the dissolution of Al and Zn atoms into the matrix,which significantly enhances tensile strength.However,excessive solute content leads to a marked decline in ductility.Scanning probe microscope(SPM)reveals an elevated work function due to the dissolution of Al and Zn atoms into the matrix phase,correlating with improved corrosion resistance.Comprehensive analysis demonstrates that air cooling achieves an optimal balance between tensile strength,ductility,and corrosion resistance,outperforming furnace-cooled samples and offering a pragmatic compromise compared to water-quenched specimens with higher strength but brittle failure.These findings establish a robust framework for designing LAZ832 alloys with tailored microstructures and multi-property optimization,advancing their application in lightweight engineering fields.展开更多
Ultralight Mg-Li alloys offer promising applications across various fields.Mg-Li alloys enriched with Al and Zn hold theoretical potential for achieving excellent mechanical strength and corrosion resistance.However,t...Ultralight Mg-Li alloys offer promising applications across various fields.Mg-Li alloys enriched with Al and Zn hold theoretical potential for achieving excellent mechanical strength and corrosion resistance.However,the structural and performance characteristics of such Mg-Li alloys,particularly after thermo-mechanical processing,remain inadequately explored and understood.This study investigated the mi-crostructural evolution of a Mg-9Li-5Al-4Zn alloy after friction stir processing and its consequent effects on the mechanical and corrosion performance.The grain size of the alloy was effectively refined and sta-bilized during friction stir processing at various heat inputs.The yield strength of the alloy increased by 86.4%after friction stir processing under the highest heat input condition,which was attributed to fine grain strengthening,solid solution strengthening and dispersion strengthening.Concurrently,the alloy ex-perienced a slight decrease in elongation after the friction stir processing.The alloy subjected to friction stir processing with the highest heat input exhibited a minimal corrosion current density of 6.10×10^(−6) A/cm^(2),which was only 25%of the base metal.The enhanced anti-corrosion properties can be attributed to the dispersion and distribution of precipitated particles induced by friction stir processing,which hin-dered the micro-galvanic corrosion and promoted the generation of a compact surface film,leading to minimal and uniform corrosion.This investigation can be significant for understanding the metallurgical mechanisms and performance evolution of Mg-Li alloys during thermomechanical processes.展开更多
Microstructure control always plays a key role in enhancing properties of high-strength Al alloys. Attempts to improve the microstructure of 7000 series alloys by addition of 1.0 wt% Li have been made for a long time,...Microstructure control always plays a key role in enhancing properties of high-strength Al alloys. Attempts to improve the microstructure of 7000 series alloys by addition of 1.0 wt% Li have been made for a long time, but unsystematically. This article compares the microstructural features of 1.0 wt% Li-containing A1-Zn-Mg-Cu alloy with those of Li-free Al-Zn-Mg-Cu alloy by using differential scanning calorimetric （DSC） techniques, Vickers microhardness and transmission electron microscopy （TEM）. The results show the dominance of Guinier Preston （GP） zones, η＇ or η phases in 1.0 wt% Li-containing Al-Zn-Mg-Cu alloy, and confirm the capability of Li to retard the rate of precipitates growth and coarsening.展开更多
Al-5.6Zn-3.0Mg-1.6Cu-1.1Li-0.24Cr alloys and Al-8.0Zn-2.4Mg-2.4Cu-1.1Li-0.18Zr alloys (mass fraction, %) were aged by different processes. The microstructure and mechanical properties were determined by transmission e...Al-5.6Zn-3.0Mg-1.6Cu-1.1Li-0.24Cr alloys and Al-8.0Zn-2.4Mg-2.4Cu-1.1Li-0.18Zr alloys (mass fraction, %) were aged by different processes. The microstructure and mechanical properties were determined by transmission electron microscopy(TEM), tensile test and Vicker's hardness test. The experimental results show that the most signified hardening is obtained by double-ageing or multi-ageing for the Al-Zn-Mg-Cu-Li alloys. The yield strength and the elastic modulus of the Li-containing alloys have relationships with ageing processes. The elastic modulus of Li-containing alloys decreases with the increment of precipitates though it is higher than that of Al-Zn-Mg-Cu alloy.展开更多
Small angle X-ray scattering has been used to study the variation of microstructure parameters in an Al-Zn-Mg-Cu-Li alloy aged at various temperatures for various durations. Coarsening of precipitates was studied by a...Small angle X-ray scattering has been used to study the variation of microstructure parameters in an Al-Zn-Mg-Cu-Li alloy aged at various temperatures for various durations. Coarsening of precipitates was studied by analyzing the curve of kinetics strength vs the cube of radius. The results show that the coarsening of precipitates conforms to LSW principle. In addition, the characteristic of s^3J(s) vs s curves was analyzed. The results show that the curves for samples aged at 160 ℃ for various durations(24, 48 and 96 h) have negative deviation, which maybe results in the formation of certain new precipitate. In the other aging treatment states, the curves conform to Porod principle which means there is sharp boundary between the precipitates and matrix.展开更多
The microstructure and mechanical properties of as-cast Al−Cu−Li−Mg−Zn alloys fabricated by conventional gravity casting and centrifugal casting techniques combined with rapid solidification were investigated.Experime...The microstructure and mechanical properties of as-cast Al−Cu−Li−Mg−Zn alloys fabricated by conventional gravity casting and centrifugal casting techniques combined with rapid solidification were investigated.Experimental results demonstrated that compared with the gravity casting technique,the water-cooling centrifugal casting technique significantly reduces porosity,refinesα(Al)grains and secondary phases,modifies the morphology of secondary phases,and mitigates both macro-and micro-segregation.These improvements arise from the synergistic effects of the vigorous backflow,centrifugal field,vibration and rapid solidification.Porosity and coarse plate-like Al13Fe4/Al7Cu2Fe phase result in the fracture before the gravity-cast alloy reaches the yield point.The centrifugal-cast alloy,however,exhibits an ultra-high yield strength of 292.0 MPa and a moderate elongation of 6.1%.This high yield strength is attributed to solid solution strengthening(SSS)of 225.3 MPa,and grain boundary strengthening(GBS)of 35.7 MPa.Li contributes the most to SSS with a scaling factor of 7.9 MPa·wt.%^(-1).The elongation of the centrifugal-cast alloy can be effectively enhanced by reducing the porosity and segregation behavior,refining the microstructure and changing the morphology of secondary phases.展开更多
基金supported by the Foundation Strengthening Plan Technical Field Fund(No.2021-JJ-0112)Major Scientific and Technological Innovation Project of Luoyang(No.2201029A)+1 种基金National Science and Technology Innovation Special Zone(No.02-14-01)National Natural Science Foundation of China(No.U2037601).
文摘In this work,the aging response and mechanism of dual-phase Mg-Li-Al-Zn alloy at various temperatures are investigated.The results show that the strengthening after quenching is primarily attributed to the immediate precipitation of the semi-coherent~Mg_(3)Zn phase.The aging softening of the studied alloy is mainly caused by the rapid transformation of the strengthening~Mg_(3)Zn phase to the softening MgLi(Al,Zn)phase,along with the coarsening of theα-Mg matrix and precipitates withinβ-Li matrix.Further analysis indicates that the quick precipitation and transformation of~Mg_(3)Zn is a consequence of the high diffusion rate of solute atoms,resulting from dense vacancy concentration in theβ-Li matrix.This research bridges a critical gap in the study of aging mechanism in the dual-phase Mg-Li-Al-Zn alloy,providing a theoretical basis for the development and application of high-performance and thermal-stable Mg-Li alloys.
基金Project(2009AA03Z525)supported by the National High-tech Research and Development Program of ChinaProject(NCET-08-0080)supported by the Program of New Century Excellent Talents of the Ministry of Education of ChinaProject(20082172)supported by the Natural Science Foundation of Liaoning Province,China
文摘Effects of electromagnetic stirring on the microstructure and mechanical properties of the magnesium-lithium-aluminum alloy were studied.The results reveal that,the morphology of theαphase changes from the long block to globular structure andβ phase distributes more widely in the periphery ofαphase when the electromagnetic stirring voltage is higher than 110 V.The mechanical properties are increased significantly with the increasing electromagnetic stirring.The tensile strength is improved from 172 to 195 MPa,and the elongation is increased from 10.65%to 25.75%.
基金the financial support of the Scientific Research Starting Foundation of Anhui Polytechnic University of China(Grant No.2200YQQ049)the Excellent Scientific Research and Innovation Teams of Anhui Province,China(Grant No.2022AH010059).
文摘Annealing treatment is an effective strategy to enhance the comprehensive properties of Mg-8Li-3Al-2Zn(LAZ832)alloy,where the cooling rate plays a decisive role in tailoring microstructure and performance.This study systematically investigates the effects of cooling rates,controlled via water quenching(WC),air cooling(AC),and furnace cooling(FC),on the phase evolution,mechanical properties,and corrosion resistance of LAZ832.The annealed microstructure consists ofα-Mg,β-Li,AlLi,and MgLi_(2)Al phases,and the volume fraction of Al-Li phases(AlLi and MgLi_(2)Al)increases as the cooling rate decreases.Strengthening mechanisms are dominated by solid solution strengthening,driven by the dissolution of Al and Zn atoms into the matrix,which significantly enhances tensile strength.However,excessive solute content leads to a marked decline in ductility.Scanning probe microscope(SPM)reveals an elevated work function due to the dissolution of Al and Zn atoms into the matrix phase,correlating with improved corrosion resistance.Comprehensive analysis demonstrates that air cooling achieves an optimal balance between tensile strength,ductility,and corrosion resistance,outperforming furnace-cooled samples and offering a pragmatic compromise compared to water-quenched specimens with higher strength but brittle failure.These findings establish a robust framework for designing LAZ832 alloys with tailored microstructures and multi-property optimization,advancing their application in lightweight engineering fields.
基金supported by the National Natural Science Foundation of China(grant Nos.U23A20541 and 52305385).
文摘Ultralight Mg-Li alloys offer promising applications across various fields.Mg-Li alloys enriched with Al and Zn hold theoretical potential for achieving excellent mechanical strength and corrosion resistance.However,the structural and performance characteristics of such Mg-Li alloys,particularly after thermo-mechanical processing,remain inadequately explored and understood.This study investigated the mi-crostructural evolution of a Mg-9Li-5Al-4Zn alloy after friction stir processing and its consequent effects on the mechanical and corrosion performance.The grain size of the alloy was effectively refined and sta-bilized during friction stir processing at various heat inputs.The yield strength of the alloy increased by 86.4%after friction stir processing under the highest heat input condition,which was attributed to fine grain strengthening,solid solution strengthening and dispersion strengthening.Concurrently,the alloy ex-perienced a slight decrease in elongation after the friction stir processing.The alloy subjected to friction stir processing with the highest heat input exhibited a minimal corrosion current density of 6.10×10^(−6) A/cm^(2),which was only 25%of the base metal.The enhanced anti-corrosion properties can be attributed to the dispersion and distribution of precipitated particles induced by friction stir processing,which hin-dered the micro-galvanic corrosion and promoted the generation of a compact surface film,leading to minimal and uniform corrosion.This investigation can be significant for understanding the metallurgical mechanisms and performance evolution of Mg-Li alloys during thermomechanical processes.
文摘Microstructure control always plays a key role in enhancing properties of high-strength Al alloys. Attempts to improve the microstructure of 7000 series alloys by addition of 1.0 wt% Li have been made for a long time, but unsystematically. This article compares the microstructural features of 1.0 wt% Li-containing A1-Zn-Mg-Cu alloy with those of Li-free Al-Zn-Mg-Cu alloy by using differential scanning calorimetric （DSC） techniques, Vickers microhardness and transmission electron microscopy （TEM）. The results show the dominance of Guinier Preston （GP） zones, η＇ or η phases in 1.0 wt% Li-containing Al-Zn-Mg-Cu alloy, and confirm the capability of Li to retard the rate of precipitates growth and coarsening.
基金Project(2001AA332030) supported by the Advanced Materials Committee of China
文摘Al-5.6Zn-3.0Mg-1.6Cu-1.1Li-0.24Cr alloys and Al-8.0Zn-2.4Mg-2.4Cu-1.1Li-0.18Zr alloys (mass fraction, %) were aged by different processes. The microstructure and mechanical properties were determined by transmission electron microscopy(TEM), tensile test and Vicker's hardness test. The experimental results show that the most signified hardening is obtained by double-ageing or multi-ageing for the Al-Zn-Mg-Cu-Li alloys. The yield strength and the elastic modulus of the Li-containing alloys have relationships with ageing processes. The elastic modulus of Li-containing alloys decreases with the increment of precipitates though it is higher than that of Al-Zn-Mg-Cu alloy.
文摘Small angle X-ray scattering has been used to study the variation of microstructure parameters in an Al-Zn-Mg-Cu-Li alloy aged at various temperatures for various durations. Coarsening of precipitates was studied by analyzing the curve of kinetics strength vs the cube of radius. The results show that the coarsening of precipitates conforms to LSW principle. In addition, the characteristic of s^3J(s) vs s curves was analyzed. The results show that the curves for samples aged at 160 ℃ for various durations(24, 48 and 96 h) have negative deviation, which maybe results in the formation of certain new precipitate. In the other aging treatment states, the curves conform to Porod principle which means there is sharp boundary between the precipitates and matrix.
基金financially supported by the Natural Science Foundation of Ningbo,China (No.2023J053)。
文摘The microstructure and mechanical properties of as-cast Al−Cu−Li−Mg−Zn alloys fabricated by conventional gravity casting and centrifugal casting techniques combined with rapid solidification were investigated.Experimental results demonstrated that compared with the gravity casting technique,the water-cooling centrifugal casting technique significantly reduces porosity,refinesα(Al)grains and secondary phases,modifies the morphology of secondary phases,and mitigates both macro-and micro-segregation.These improvements arise from the synergistic effects of the vigorous backflow,centrifugal field,vibration and rapid solidification.Porosity and coarse plate-like Al13Fe4/Al7Cu2Fe phase result in the fracture before the gravity-cast alloy reaches the yield point.The centrifugal-cast alloy,however,exhibits an ultra-high yield strength of 292.0 MPa and a moderate elongation of 6.1%.This high yield strength is attributed to solid solution strengthening(SSS)of 225.3 MPa,and grain boundary strengthening(GBS)of 35.7 MPa.Li contributes the most to SSS with a scaling factor of 7.9 MPa·wt.%^(-1).The elongation of the centrifugal-cast alloy can be effectively enhanced by reducing the porosity and segregation behavior,refining the microstructure and changing the morphology of secondary phases.
