Micro-arc oxidation(MAO)flm can only provide common mechanical protection for magnesium(Mg)–lithium(Li)alloys.These alloys are susceptible to severe localized corrosion,if the MAO flm is disrupted.This work reports t...Micro-arc oxidation(MAO)flm can only provide common mechanical protection for magnesium(Mg)–lithium(Li)alloys.These alloys are susceptible to severe localized corrosion,if the MAO flm is disrupted.This work reports the successful hydrothermal preparation of a MgLiAlCe-LDHs@GO flm on a MAO-coated Mg–Li alloy following Ce confnement.The graphene oxide(GO)sheet increased the difusion path of the corrosive media,and the addition of rare-earth cerium ions(Ce^(3+))endowed the flm with a certain self-healing ability,which signifcantly improved the corrosion resistance of the flm,and the corrosion current density(icorr)reached 3.27×10^(−8)A cm^(−2).The synergistic action of GO and Ce^(3+)can achieve long-term corrosion protection for the substrate.The corrosion resistance mechanism of MgLiAlCe-LDHs@GO flm was discussed by the scanning vibration electrode technique(SVET).展开更多
Formation of super-hydrophobic and corrosion-resistant coatings can provide significant corrosion protection to magnesium alloys.However,it remains a grand challenge to produce such coatings for magnesium-lithium allo...Formation of super-hydrophobic and corrosion-resistant coatings can provide significant corrosion protection to magnesium alloys.However,it remains a grand challenge to produce such coatings for magnesium-lithium alloys due to their high chemical reactivity.Herein,a one-step hydrothermal processing was developed using a stearic-acid-based precursor medium,which enables the hydrothermal conversion and the formation of low surface energy materials concurrently to produce the super-hydrophobic and corrosion-resistant coating.The multiscale microstructures with nanoscale stacks and microscale spheres on the surface,as well as the through-thickness stearates,lead to the super-hydrophobicity and excellent corrosion resistance of the obtained coating.展开更多
The poor corrosion resistance of magnesiumlithium alloy surface works against its application in aerospace,automobile,electronics,etc.In this research,some kinds of non-toxic and non-polluting rare earth and silane(RE...The poor corrosion resistance of magnesiumlithium alloy surface works against its application in aerospace,automobile,electronics,etc.In this research,some kinds of non-toxic and non-polluting rare earth and silane(RE-Si)composite conversion coatings were built up on Mg-Li alloy surface,and formation process of coatings was investigated.The parameters for coating preparation were determined,including immersion time and temperature,pH value of conversion solution and curing time.The optimized technological parameters for preparation of RE-Si composite coating were finally confirmed.The influence of doping nanoparticles on RE-Si composite coating was also discussed,and the microstructure of coatings shows that the addition of nanoparticles can effectively improve the compactness and uniformity of composite coating.The corrosion resistance of specimens with RE-Si composite conversion coating is improved to a great extent compared with those of substrate or specimens with single rare earth(RE)conversion coating or with silane coating.The result also indicates that corrosion resistance of RE-Si composite coating doping with nanoparticles is further improved.Composition of the composite coatings was analyzed,and the effect of RE elements and silane on coating formation process was investigated.Corrosion resistance mechanism of composite coatings on Mg-Li alloy surface was discussed.展开更多
It is recently suggested that air-formed film plays an important role in controlling corrosion resistance of Mg-Li alloys. However, the structure of the air-formed film and its effect on corrosion resistance of Mg-Li ...It is recently suggested that air-formed film plays an important role in controlling corrosion resistance of Mg-Li alloys. However, the structure of the air-formed film and its effect on corrosion resistance of Mg-Li alloys has not been fully understood. Firstly, the air-formed films formed on α and β phases in a dual-phase LZ91 Mg-Li alloy after exposure to laboratory air for up to 48 h have been examined by SEM under the assistance of ultramicrotomy. Then, the effect of the air-formed film on surface potential and, consequently, corrosion/oxidation behavior of the alloy has been investigated. Finally, in order to exclude the influence from α phase, the structure of the air-formed film on β phase and its effect on corrosion/oxidation behavior of Mg-Li alloys have been studied based on a single-phase LA141 Mg-Li alloy. The results show that the air-formed film is thin and negligible on α phase but thick on β phase after prolonged exposure to laboratory air. The thick air-formed film on β phase has a multilayer structure with an inner layer consisting of Mg O/Mg(OH)_(2) and outer layer consisting of Li_(2)CO_(3), which greatly elevates the surface potential of β phase in air. Both LZ91 and LA141 Mg-Li alloys firstly undergo uniform corrosion and then filiform corrosion when immersed in Na Cl solution and the pre-existed air-formed film on β-Li phase can retard the occurrence of filiform corrosion in the alloys.展开更多
In this study,friction stir welding(FSW)technique was applied to the LAZ933 magnesium-lithium(Mg-Li)alloy.Microstructure,mechanical properties and corrosion behaviors of friction stir welded LAZ933 magnesium-lithium a...In this study,friction stir welding(FSW)technique was applied to the LAZ933 magnesium-lithium(Mg-Li)alloy.Microstructure,mechanical properties and corrosion behaviors of friction stir welded LAZ933 magnesium-lithium alloy were analyzed by optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffractometry(XRD),transmission electron microscopy(TEM),hardness,tensile,and electrochemical test.The experimental results indicated that FSW resulted in significant refinement ofβphase,reduction ofαphase content as well as dissolution of Mg_(17)Al_(12)and AlLi(γ)precipitates in the nugget zone(NZ).The generated MgLi_(2)Al(θ)precipitates in the NZ and heat-affected zone(HAZ)which had a coherent structure with the matrix could significantly strengthen the Mg-Li alloy.The ultimate tensile strength of the joint reached 163.5 MPa,and elongation reached 15.21%.In the weakest area of the weld(HAZ),the strengthening caused by the solid solution ofαphases and formation of θ precipitates compensated the strength loss induced by the phase coarsening by thermal exposure in FSW,resulting in the joint fractured in the base metal(BM)and showed a ductile pattern.The corrosion current density changed from 4.831×10^(-5)A/cm^(2)to 2.054×10^(-5)A/cm^(2),which indicated that the weld had better corrosion resistance than the BM.展开更多
In this review paper, the research progress on corrosion behavior of hexagonal close-packed(HCP) singular phase, body cubic-centered(BCC) singular phase and(HCP + BCC) duplex-structured Mg–Li alloys has been summariz...In this review paper, the research progress on corrosion behavior of hexagonal close-packed(HCP) singular phase, body cubic-centered(BCC) singular phase and(HCP + BCC) duplex-structured Mg–Li alloys has been summarized and reviewed, and the future trend about the studies on corrosion behavior of Mg–Li-based alloys and possible solving methods for the improvement in corrosion resistance are discussed also.展开更多
TiO_(2)has been explored in hybrid magnesium-lithium batteries(HMLBs)due to the advantages of low self-discharge and small volume expansion during ion insertion.However,how to improve the inherently low ionic and elec...TiO_(2)has been explored in hybrid magnesium-lithium batteries(HMLBs)due to the advantages of low self-discharge and small volume expansion during ion insertion.However,how to improve the inherently low ionic and electrical conductivity of TiO_(2)is the problem that needs to be solved.In this work,a smart strategy is adopted to prepare cobalt-doped TiO_(2)@C(Co^(4+)-TiO_(2)@C)hierarchical nanocomposite derived from Co(II)(OH)n@Ti3C2.Compared with TiO_(2)@C(without cobalt doping),Co^(4+)-TiO_(2)@C shows the highest specific capacity(154.7 mAh·g^(-1)at 0.1 A·g^(-1)after 200 cycles)and extraordinary rate performance in HMLBs.The excellent electrochemical performance of Co4+-TiO_(2)@C is ascribed to the synergistic effect of the hierarchical structure and cobalt-doping.Both experimental results and density functional theory(DFT)calculation reveal that the cobalt-doping has effectively improved the electronic conductivity and reduced the Li+migration barrier.This work provides a new insight to design TiO_(2)-based cathode materials with high-performance in HMLBs.展开更多
In this work,through performing microstructural characterization,tensile testing and failure analysis,the influence of electrochemical hydrogen charging on the microstructure and mechanical behavior of an as-cast Mg-8...In this work,through performing microstructural characterization,tensile testing and failure analysis,the influence of electrochemical hydrogen charging on the microstructure and mechanical behavior of an as-cast Mg-8wt.%Li alloy was investigated.It revealed that after being hydrogen charged at 50 mA/cm2 for respectively 3 h,6 h and 18 h in 0.1 M NaCl solution,obvious HID occurred and the damage degree was gradually increased with the hydrogen charging time.For the sample being hydrogen charged for 3 h,micro pores with the diameter ranging from 10~30µm were formed and preferentially present inα-Mg phase.Moreover,micro cracks with the length ranging from 10~50µm mainly initiated inα-Mg phase,atα-Mg/β-Li interfaces and the peripheries of pores.With the increase of hydrogen charging time,the numbers of pores and cracks were obviously increased.Tensile results revealed that the hydrogen charging can simultaneously decrease the tensile strength and ductility of the alloy.Compared with the uncharged sample,the tensile yield strength,ultimate tensile strength and the elongation ratio to failure were respectively reduced by 5.7%,7.3%,31.7%for the 3h-charged sample and 24.6%,24.8%,67.0%for the 18h-charged sample.Failure analysis indicated that hydrogen charging can induce the brittle cracking of the alloy and the size of brittle cracking region being composed of quasi-cleavage facets and interfacial cracks on the fracture surfaces was increased with the hydrogen charging time.展开更多
基金supported by the National Key R&D Program of China(2021YFB3701100)the National Natural Science Foundation of China(52171101)the Fundamental Research Funds for the Central Universities(2024IAIS-QN009).
文摘Micro-arc oxidation(MAO)flm can only provide common mechanical protection for magnesium(Mg)–lithium(Li)alloys.These alloys are susceptible to severe localized corrosion,if the MAO flm is disrupted.This work reports the successful hydrothermal preparation of a MgLiAlCe-LDHs@GO flm on a MAO-coated Mg–Li alloy following Ce confnement.The graphene oxide(GO)sheet increased the difusion path of the corrosive media,and the addition of rare-earth cerium ions(Ce^(3+))endowed the flm with a certain self-healing ability,which signifcantly improved the corrosion resistance of the flm,and the corrosion current density(icorr)reached 3.27×10^(−8)A cm^(−2).The synergistic action of GO and Ce^(3+)can achieve long-term corrosion protection for the substrate.The corrosion resistance mechanism of MgLiAlCe-LDHs@GO flm was discussed by the scanning vibration electrode technique(SVET).
基金support from the Fundamental Research Funds for the Central Universities of Hohai university(B200202122)National Natural Science Foundation of China(51878246 and 51979099)+1 种基金the Natural Science Foundation of Jiangsu Province of China(BK20191303)Key Research and Development Project of Jiangsu Province of China(BE2017148).
文摘Formation of super-hydrophobic and corrosion-resistant coatings can provide significant corrosion protection to magnesium alloys.However,it remains a grand challenge to produce such coatings for magnesium-lithium alloys due to their high chemical reactivity.Herein,a one-step hydrothermal processing was developed using a stearic-acid-based precursor medium,which enables the hydrothermal conversion and the formation of low surface energy materials concurrently to produce the super-hydrophobic and corrosion-resistant coating.The multiscale microstructures with nanoscale stacks and microscale spheres on the surface,as well as the through-thickness stearates,lead to the super-hydrophobicity and excellent corrosion resistance of the obtained coating.
基金financially supported by the National Natural Science Foundation of China(No.51172010)。
文摘The poor corrosion resistance of magnesiumlithium alloy surface works against its application in aerospace,automobile,electronics,etc.In this research,some kinds of non-toxic and non-polluting rare earth and silane(RE-Si)composite conversion coatings were built up on Mg-Li alloy surface,and formation process of coatings was investigated.The parameters for coating preparation were determined,including immersion time and temperature,pH value of conversion solution and curing time.The optimized technological parameters for preparation of RE-Si composite coating were finally confirmed.The influence of doping nanoparticles on RE-Si composite coating was also discussed,and the microstructure of coatings shows that the addition of nanoparticles can effectively improve the compactness and uniformity of composite coating.The corrosion resistance of specimens with RE-Si composite conversion coating is improved to a great extent compared with those of substrate or specimens with single rare earth(RE)conversion coating or with silane coating.The result also indicates that corrosion resistance of RE-Si composite coating doping with nanoparticles is further improved.Composition of the composite coatings was analyzed,and the effect of RE elements and silane on coating formation process was investigated.Corrosion resistance mechanism of composite coatings on Mg-Li alloy surface was discussed.
基金gratefully acknowledge Chongqing Talent Plan: Leading Talents in Innovation and Entrepreneurship (CQYC201903051)University Innovation Research Group of Chongqing (CXQT20023)Natural Science Foundation of Chongqing (cstc2021ycjh-bgzxm0184)。
文摘It is recently suggested that air-formed film plays an important role in controlling corrosion resistance of Mg-Li alloys. However, the structure of the air-formed film and its effect on corrosion resistance of Mg-Li alloys has not been fully understood. Firstly, the air-formed films formed on α and β phases in a dual-phase LZ91 Mg-Li alloy after exposure to laboratory air for up to 48 h have been examined by SEM under the assistance of ultramicrotomy. Then, the effect of the air-formed film on surface potential and, consequently, corrosion/oxidation behavior of the alloy has been investigated. Finally, in order to exclude the influence from α phase, the structure of the air-formed film on β phase and its effect on corrosion/oxidation behavior of Mg-Li alloys have been studied based on a single-phase LA141 Mg-Li alloy. The results show that the air-formed film is thin and negligible on α phase but thick on β phase after prolonged exposure to laboratory air. The thick air-formed film on β phase has a multilayer structure with an inner layer consisting of Mg O/Mg(OH)_(2) and outer layer consisting of Li_(2)CO_(3), which greatly elevates the surface potential of β phase in air. Both LZ91 and LA141 Mg-Li alloys firstly undergo uniform corrosion and then filiform corrosion when immersed in Na Cl solution and the pre-existed air-formed film on β-Li phase can retard the occurrence of filiform corrosion in the alloys.
基金sponsored by the National Nature Science Foundation of China(No.51974100)Taishan Scholars Foundation of Shandong Province(No.tsqn202211089)+1 种基金the Natural Science Foundation of Shandong Province(No.ZR201911140194)the Program of Shanghai Academic/Technology Research Leader(No.22XD1433000)。
文摘In this study,friction stir welding(FSW)technique was applied to the LAZ933 magnesium-lithium(Mg-Li)alloy.Microstructure,mechanical properties and corrosion behaviors of friction stir welded LAZ933 magnesium-lithium alloy were analyzed by optical microscopy(OM),scanning electron microscopy(SEM),X-ray diffractometry(XRD),transmission electron microscopy(TEM),hardness,tensile,and electrochemical test.The experimental results indicated that FSW resulted in significant refinement ofβphase,reduction ofαphase content as well as dissolution of Mg_(17)Al_(12)and AlLi(γ)precipitates in the nugget zone(NZ).The generated MgLi_(2)Al(θ)precipitates in the NZ and heat-affected zone(HAZ)which had a coherent structure with the matrix could significantly strengthen the Mg-Li alloy.The ultimate tensile strength of the joint reached 163.5 MPa,and elongation reached 15.21%.In the weakest area of the weld(HAZ),the strengthening caused by the solid solution ofαphases and formation of θ precipitates compensated the strength loss induced by the phase coarsening by thermal exposure in FSW,resulting in the joint fractured in the base metal(BM)and showed a ductile pattern.The corrosion current density changed from 4.831×10^(-5)A/cm^(2)to 2.054×10^(-5)A/cm^(2),which indicated that the weld had better corrosion resistance than the BM.
基金supported by the National Key Research and Development Program of China (Nos. 2017YFB0702001 and 2016YFB0301105)the National Natural Science Foundation of China (Nos. 51701129 and 51871211)the postdoctoral start fund of Shenyang Ligong University (No. 105000100006)
文摘In this review paper, the research progress on corrosion behavior of hexagonal close-packed(HCP) singular phase, body cubic-centered(BCC) singular phase and(HCP + BCC) duplex-structured Mg–Li alloys has been summarized and reviewed, and the future trend about the studies on corrosion behavior of Mg–Li-based alloys and possible solving methods for the improvement in corrosion resistance are discussed also.
基金supported by the National Natural Science Foundation of China(No.22278347)the Graduate Research Innovation Project of Xinjiang(No.XJGRI2017002)the Doctoral Innovation Program of Xinjiang University(No.XJUBSCX-2017012).
文摘TiO_(2)has been explored in hybrid magnesium-lithium batteries(HMLBs)due to the advantages of low self-discharge and small volume expansion during ion insertion.However,how to improve the inherently low ionic and electrical conductivity of TiO_(2)is the problem that needs to be solved.In this work,a smart strategy is adopted to prepare cobalt-doped TiO_(2)@C(Co^(4+)-TiO_(2)@C)hierarchical nanocomposite derived from Co(II)(OH)n@Ti3C2.Compared with TiO_(2)@C(without cobalt doping),Co^(4+)-TiO_(2)@C shows the highest specific capacity(154.7 mAh·g^(-1)at 0.1 A·g^(-1)after 200 cycles)and extraordinary rate performance in HMLBs.The excellent electrochemical performance of Co4+-TiO_(2)@C is ascribed to the synergistic effect of the hierarchical structure and cobalt-doping.Both experimental results and density functional theory(DFT)calculation reveal that the cobalt-doping has effectively improved the electronic conductivity and reduced the Li+migration barrier.This work provides a new insight to design TiO_(2)-based cathode materials with high-performance in HMLBs.
基金supported by the National Natural Science Foundation of China Projects under grant[nos.U21A2049,52071220,51871211,51701129 and 51971054]Liaoning Province's project of“Revitalizing Liaoning Talents”(XLYC1907062)+6 种基金the Doctor Startup Fund of Natural Science Foundation Program of Liaoning Province(no.2019-BS-200)the Strategic New Industry Development Special Foundation of Shenzhen(JCYJ20170306141749970)the funds of International Joint Laboratory for Light Alloys,Liaoning BaiQianWan Talents Program,the Domain Foundation of Equipment Advance Research of 13th Five-year Plan(61409220118)National Key Research and Development Program of China under grant[nos.2017YFB0702001 and 2016YFB0301105]the Innovation Fund of Institute of Metal Research(IMR),Chinese Academy of Sciences(CAS),the National Basic Research Program of China(973 Program)project under grant no.2013CB632205the Fundamental Research Fund for the Central Universities under grant[no.N2009006]Bintech-IMR R&D Program[no.GYY-JSBU-2022-009].
文摘In this work,through performing microstructural characterization,tensile testing and failure analysis,the influence of electrochemical hydrogen charging on the microstructure and mechanical behavior of an as-cast Mg-8wt.%Li alloy was investigated.It revealed that after being hydrogen charged at 50 mA/cm2 for respectively 3 h,6 h and 18 h in 0.1 M NaCl solution,obvious HID occurred and the damage degree was gradually increased with the hydrogen charging time.For the sample being hydrogen charged for 3 h,micro pores with the diameter ranging from 10~30µm were formed and preferentially present inα-Mg phase.Moreover,micro cracks with the length ranging from 10~50µm mainly initiated inα-Mg phase,atα-Mg/β-Li interfaces and the peripheries of pores.With the increase of hydrogen charging time,the numbers of pores and cracks were obviously increased.Tensile results revealed that the hydrogen charging can simultaneously decrease the tensile strength and ductility of the alloy.Compared with the uncharged sample,the tensile yield strength,ultimate tensile strength and the elongation ratio to failure were respectively reduced by 5.7%,7.3%,31.7%for the 3h-charged sample and 24.6%,24.8%,67.0%for the 18h-charged sample.Failure analysis indicated that hydrogen charging can induce the brittle cracking of the alloy and the size of brittle cracking region being composed of quasi-cleavage facets and interfacial cracks on the fracture surfaces was increased with the hydrogen charging time.
