The weak corrosion resistance of magnesium and its alloys greatly limited the industrial application.Though functional self-healing coatings have been proposed as countermeasures,repeated damages on coatings under pra...The weak corrosion resistance of magnesium and its alloys greatly limited the industrial application.Though functional self-healing coatings have been proposed as countermeasures,repeated damages on coatings under practical installation and complex external environments could require self-adaptive cor-rosion protection against multiple abrasions.In this study,an ultra-high corrosion-resistant Mg-1Zn-1Sc(wt.%)alloy with a corrosion rate of 0.087 mm/y has been designed and prepared,which has fine grains and uniform structure of a nano-scale ScZn phase with low potential.A unique and dense corrosion prod-uct film with a three-layered structure was found and studied on Mg-1Zn-1Sc alloy,providing excellent corrosion protection.In addition,the formation and protection mechanisms of the three-layered corrosion product film on Mg-1Zn-1Sc alloy have been discussed and proposed.The growth behavior of protective corrosion product film could be driven by the synergy of Sc and Zn elements.Furthermore,with the in-crease of Sc content,the strength,plasticity,and corrosion resistance of Mg-1Zn-x Sc(x=0,0.2,0.6,1.0,in wt.%)alloys increased simultaneously.The high corrosion resistance and moderate mechanical perfor-mance qualify Mg-1Zn-1Sc alloy as a promising candidate for diverse industrial applications.展开更多
The microstructure and corrosion behaviour of hot-rolled Mg-3Zn-1Y-xCu alloys(x=0,1,3,5,wt%)were investigated.Results show that all Mg-3Zn-1Y-xCu alloys mainly consist ofα-Mg matrix and Mg_(3)Zn_(6)Y phases.The addit...The microstructure and corrosion behaviour of hot-rolled Mg-3Zn-1Y-xCu alloys(x=0,1,3,5,wt%)were investigated.Results show that all Mg-3Zn-1Y-xCu alloys mainly consist ofα-Mg matrix and Mg_(3)Zn_(6)Y phases.The addition of Cu element promotes the formation of MgZnCu phase,and the amount of MgZnCu phase is increased with the increase in Cu content.Electrochemical and immersion test results show that the corrosion resistance of Mg-3Zn-1Y-xCu alloys is deteriorated after Cu addition,which can be attributed to the influence of the microstructure of alloys and the properties of the formed corrosion product film.The MgZnCu phase with high electrochemical potential accelerates the micro-galvanic corrosion as strong cathodic sites,and the decreased protection effect of the corrosion product film results from the variation in PBR value of the related compounds.展开更多
A medium-carbon low-alloy steel with designed chemical composition was investigated.The steel exhibits an excellent product of strength and elongation value of 31,832 MPa%through quenching and partitioning treatment,w...A medium-carbon low-alloy steel with designed chemical composition was investigated.The steel exhibits an excellent product of strength and elongation value of 31,832 MPa%through quenching and partitioning treatment,with a tensile strength of 1413 MPa and elongation of 22%.X-ray diffraction analysis and transmission electron microscopy characterizations confirm that the retained austenite in the specimens undergoes stress-induced phase transformation to the martensite and hexagonal phases,namely the transformation-induced plasticity(TRIP)effect is triggered.This TRIP effect,triggered by the stress-induced phase transition of retained austenite,is responsible for the excellent mechanical properties obtained in the steel.For further investigating the stress-induced phase transition mechanism,thermodynamic methods are applied.Gibbs free energy of face-centered cubic-Fe,ε-Fe,ω-Fe and body-centered cubic-Fe associated with the stress-induced phase transition was calculated using molecular dynamics simulations,and a calculation method of strain energy in thermodynamic units for the stress-induced martensitic transformation is presented.The final results reveal the process and thermodynamic mechanism of stress-induced martensitic transformation in medium-carbon steels,in which the hexagonal phase can participate in the process as an intermediate product.展开更多
A novel Cu?6.5Ni?1Al?1Si?0.15Mg?0.15Ce alloy with super-high strength was designed and its corrosion behavior in3.5%NaCl solution at25°C was investigated by the means of SEM observation,TEM observation and XPS an...A novel Cu?6.5Ni?1Al?1Si?0.15Mg?0.15Ce alloy with super-high strength was designed and its corrosion behavior in3.5%NaCl solution at25°C was investigated by the means of SEM observation,TEM observation and XPS analysis.The alloy after solution treatment,80%cold rolling and aging at450°C for1h had the best comprehensive properties with hardness of HV314,electrical conductivity of19.4%IACS,tensile strength of1017MPa,and average annual corrosion rate of0.028mm/a.The oxides and chloride products formed at first,followed by the formation of dyroxides products.The alloy showed super-high strength,good electrical conductivity and corrosion resistant because Ni2Si hindered the precipitation of large NiAl at the grain boundary and the denickelefication of the alloy.展开更多
The corrosion degradation behavior of a Mg-Ca alloy with high Ca content aiming for a potential bone repair material in the simulated body fluid（SBF） was investigated.The microstructure and phase constitution of the...The corrosion degradation behavior of a Mg-Ca alloy with high Ca content aiming for a potential bone repair material in the simulated body fluid（SBF） was investigated.The microstructure and phase constitution of the pristine Mg-30%Ca（mass fraction） alloy were characterized with scanning electron microscopy（SEM） and X-ray diffraction（XRD）.The Mg-30%Ca alloy samples were immersed in the SBF for 90 d,and the morphology,composition and cytotoxicity of the final corrosion product were examined.It is found that Mg-30%Ca alloy is composed of α-Mg and Mg2 Ca phases.During the corrosion process in the SBF,the Mg2 Ca phase acts as an anode and the α-Mg phase acts as a cathode.The final corrosion product of the Mg-30%Ca alloy in SBF includes a small amount of black precipitates and white suspended particles.The white suspended particles are Mg（OH）2 and the black particles are believed to have a core-shell structure.The cytotoxicity experiments indicate that these black precipitates do not induce toxicity to cells.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52225101 and 52171103)the National Key R&D Program of China(No.2021YFB3701100)+1 种基金the Guangdong Major Project of Basic and Applied Basic Research(No.2020B0301030006)the Fundamental Research Funds for the Central Universities(No.2020CDJDPT001).
文摘The weak corrosion resistance of magnesium and its alloys greatly limited the industrial application.Though functional self-healing coatings have been proposed as countermeasures,repeated damages on coatings under practical installation and complex external environments could require self-adaptive cor-rosion protection against multiple abrasions.In this study,an ultra-high corrosion-resistant Mg-1Zn-1Sc(wt.%)alloy with a corrosion rate of 0.087 mm/y has been designed and prepared,which has fine grains and uniform structure of a nano-scale ScZn phase with low potential.A unique and dense corrosion prod-uct film with a three-layered structure was found and studied on Mg-1Zn-1Sc alloy,providing excellent corrosion protection.In addition,the formation and protection mechanisms of the three-layered corrosion product film on Mg-1Zn-1Sc alloy have been discussed and proposed.The growth behavior of protective corrosion product film could be driven by the synergy of Sc and Zn elements.Furthermore,with the in-crease of Sc content,the strength,plasticity,and corrosion resistance of Mg-1Zn-x Sc(x=0,0.2,0.6,1.0,in wt.%)alloys increased simultaneously.The high corrosion resistance and moderate mechanical perfor-mance qualify Mg-1Zn-1Sc alloy as a promising candidate for diverse industrial applications.
基金Fundamental Research Program of Shanxi Province(202203021222188,202303021211166)Central Guiding Science and Technology Development of Local Fund(YDZJSK20231A046)Key Scientific Research Project in Shanxi Province(202102050201003,202203D111001)。
文摘The microstructure and corrosion behaviour of hot-rolled Mg-3Zn-1Y-xCu alloys(x=0,1,3,5,wt%)were investigated.Results show that all Mg-3Zn-1Y-xCu alloys mainly consist ofα-Mg matrix and Mg_(3)Zn_(6)Y phases.The addition of Cu element promotes the formation of MgZnCu phase,and the amount of MgZnCu phase is increased with the increase in Cu content.Electrochemical and immersion test results show that the corrosion resistance of Mg-3Zn-1Y-xCu alloys is deteriorated after Cu addition,which can be attributed to the influence of the microstructure of alloys and the properties of the formed corrosion product film.The MgZnCu phase with high electrochemical potential accelerates the micro-galvanic corrosion as strong cathodic sites,and the decreased protection effect of the corrosion product film results from the variation in PBR value of the related compounds.
基金supported by the National Key Research and Development Program of China(Grant No.2018YFB0703904).
文摘A medium-carbon low-alloy steel with designed chemical composition was investigated.The steel exhibits an excellent product of strength and elongation value of 31,832 MPa%through quenching and partitioning treatment,with a tensile strength of 1413 MPa and elongation of 22%.X-ray diffraction analysis and transmission electron microscopy characterizations confirm that the retained austenite in the specimens undergoes stress-induced phase transformation to the martensite and hexagonal phases,namely the transformation-induced plasticity(TRIP)effect is triggered.This TRIP effect,triggered by the stress-induced phase transition of retained austenite,is responsible for the excellent mechanical properties obtained in the steel.For further investigating the stress-induced phase transition mechanism,thermodynamic methods are applied.Gibbs free energy of face-centered cubic-Fe,ε-Fe,ω-Fe and body-centered cubic-Fe associated with the stress-induced phase transition was calculated using molecular dynamics simulations,and a calculation method of strain energy in thermodynamic units for the stress-induced martensitic transformation is presented.The final results reveal the process and thermodynamic mechanism of stress-induced martensitic transformation in medium-carbon steels,in which the hexagonal phase can participate in the process as an intermediate product.
基金Project(51271203)supported by the National Natural Science Foundation of China
文摘A novel Cu?6.5Ni?1Al?1Si?0.15Mg?0.15Ce alloy with super-high strength was designed and its corrosion behavior in3.5%NaCl solution at25°C was investigated by the means of SEM observation,TEM observation and XPS analysis.The alloy after solution treatment,80%cold rolling and aging at450°C for1h had the best comprehensive properties with hardness of HV314,electrical conductivity of19.4%IACS,tensile strength of1017MPa,and average annual corrosion rate of0.028mm/a.The oxides and chloride products formed at first,followed by the formation of dyroxides products.The alloy showed super-high strength,good electrical conductivity and corrosion resistant because Ni2Si hindered the precipitation of large NiAl at the grain boundary and the denickelefication of the alloy.
基金Project(51271131)supported by the National Natural Science Foundation of China
文摘The corrosion degradation behavior of a Mg-Ca alloy with high Ca content aiming for a potential bone repair material in the simulated body fluid（SBF） was investigated.The microstructure and phase constitution of the pristine Mg-30%Ca（mass fraction） alloy were characterized with scanning electron microscopy（SEM） and X-ray diffraction（XRD）.The Mg-30%Ca alloy samples were immersed in the SBF for 90 d,and the morphology,composition and cytotoxicity of the final corrosion product were examined.It is found that Mg-30%Ca alloy is composed of α-Mg and Mg2 Ca phases.During the corrosion process in the SBF,the Mg2 Ca phase acts as an anode and the α-Mg phase acts as a cathode.The final corrosion product of the Mg-30%Ca alloy in SBF includes a small amount of black precipitates and white suspended particles.The white suspended particles are Mg（OH）2 and the black particles are believed to have a core-shell structure.The cytotoxicity experiments indicate that these black precipitates do not induce toxicity to cells.
