Magnesium(Mg)alloys have shown great prospects as both structural and biomedical materials,while poor corrosion resistance limits their further application.In this work,to avoid the time-consuming and laborious experi...Magnesium(Mg)alloys have shown great prospects as both structural and biomedical materials,while poor corrosion resistance limits their further application.In this work,to avoid the time-consuming and laborious experiment trial,a high-throughput computational strategy based on first-principles calculations is designed for screening corrosion-resistant binary Mg alloy with intermetallics,from both the thermodynamic and kinetic perspectives.The stable binary Mg intermetallics with low equilibrium potential difference with respect to the Mg matrix are firstly identified.Then,the hydrogen adsorption energies on the surfaces of these Mg intermetallics are calculated,and the corrosion exchange current density is further calculated by a hydrogen evolution reaction(HER)kinetic model.Several intermetallics,e.g.Y_(3)Mg,Y_(2)Mg and La_(5)Mg,are identified to be promising intermetallics which might effectively hinder the cathodic HER.Furthermore,machine learning(ML)models are developed to predict Mg intermetallics with proper hydrogen adsorption energy employing work function(W_(f))and weighted first ionization energy(WFIE).The generalization of the ML models is tested on five new binary Mg intermetallics with the average root mean square error(RMSE)of 0.11 eV.This study not only predicts some promising binary Mg intermetallics which may suppress the galvanic corrosion,but also provides a high-throughput screening strategy and ML models for the design of corrosion-resistant alloy,which can be extended to ternary Mg alloys or other alloy systems.展开更多
Magnesium(Mg)-based bone implants degrade rapidly in the physiological environment of the human body which affects their structural integrity and biocompatibility before adequate bone repair.Rare earth elements(REEs)h...Magnesium(Mg)-based bone implants degrade rapidly in the physiological environment of the human body which affects their structural integrity and biocompatibility before adequate bone repair.Rare earth elements(REEs)have demonstrated their effectiveness in tailoring the corrosion and mechanical behavior of Mg alloys.This study methodically investigated the impacts of scandium(Sc)and terbium(Tb)in tailoring the corrosion resistance,mechanical properties,and biocompatibility of Mg–0.5Zn–0.35Zr–0.15Mn(MZZM)alloys fabricated via casting and hot extrusion.Results indicate that addition of Sc and Tb improved the strength of MZZM alloys via grain size reduction and solid solution strengthening mechanisms.The extruded MZZM–(1–2)Sc–(1–2)Tb(wt.%)alloys exhibit compressive strengths within the range of 336–405 MPa,surpassing the minimum required strength of 200 MPa for bone implants by a significant margin.Potentiodynamic polarization tests revealed low corrosion rates of as–cast MZZM(0.25 mm/y),MZZM–2Tb(0.45 mm/y),MZZM–1Sc–1Tb(0.18 mm/y),and MZZM–1Sc–2Tb(0.64 mm/y),and extruded MZZM(0.17 mm/y),MZZM–1Sc(0.15 mm/y),MZZM-2Sc(0.45 mm/y),MZZM-1Tb(0.17 mm/y),MZZM-2Tb(0.10 mm/y),MZZM–1Sc-1Tb(0.14 mm/y),MZZM-1Sc-2Tb(0.40 mm/y),and MZZM–2Sc–2Tb(0.51 mm/y)alloys,which were found lower compared to corrosion rate of high-purity Mg(~1.0 mm/y)reported in the literature.Furthermore,addition of Sc,or Tb,or Sc and Tb to MZZM alloys did not adversely affect the viability of SaOS2 cells,but enhanced their initial cell attachment,proliferation,and spreading shown via polygonal shapes and filipodia.This study emphasizes the benefits of incorporating Sc and Tb elements in MZZM alloys,as they effectively enhance corrosion resistance,mechanical properties,and biocompatibility simultaneously.展开更多
By means of surface mechanical attrition treatment ( SMAT), the groin size with a diameter of aboat 60hm formed at about 20μm depth and numerous mechanical twins at about 50μm depth from the treated surface were ...By means of surface mechanical attrition treatment ( SMAT), the groin size with a diameter of aboat 60hm formed at about 20μm depth and numerous mechanical twins at about 50μm depth from the treated surface were synthesized in 316L stainless steel because of the different distributions of strain and strain rate along depth orientation. For instance the maximum strain rate reached 10^3-10^4s^-1 on the top surface. The relationship between the microsturcture and the corrosion property was studied in 0.05M H2SO4+ 0.25M Na2SO4 aqueous solution, and the results show an extreme improvement of corrosion resistance owing to the appearance of twin boundaries and the obvious reduction in corrosion resistance attributed to the presence of nanocrystaline boundaries.展开更多
A new model considering corrosion property for grounding grids diagnosis is proposed,which provides reference solutions of ambiguous branches.The constraint total least square method based on singular value decomposit...A new model considering corrosion property for grounding grids diagnosis is proposed,which provides reference solutions of ambiguous branches.The constraint total least square method based on singular value decomposition is adopted to improve the effectiveness of grounding grids' diagnosis algorithm.The improvement can weaken the influence of the model's error,which results from the differences between design paper and actual grid.Its influence on touch and step voltages caused by the interior resistance of conductors is taken into account.Simulation results show the validity of this approach.展开更多
The corrosion of steels in liquid metal lead (Pb) and bismuth (Bi) is a critical challenge in the development of accel-erator driven systems (ADS). Using a first-principles method with a slab model, we theoretic...The corrosion of steels in liquid metal lead (Pb) and bismuth (Bi) is a critical challenge in the development of accel-erator driven systems (ADS). Using a first-principles method with a slab model, we theoretically investigate the interaction between the Pb (Bi) atom and the iron (Fe) (100) surface to assess the fundamental corrosion properties. Our investigation demonstrates that both Pb and Bi atoms favorably adsorb on the (100) surface. Such an adsorption decreases the energy required for the dissociation of an Fe atom from the surface, enhancing the dissolution tendency significantly. The seg- regation of six common alloying elements (Cr, A1, Mn, Ni, Nb, and Si) to the surface and their impacts on the corrosion properties are also considered. The present results reveal that Si seems to have a relatively good performance to stabilize the surface and alleviate the dissolving trend caused by Pb and Bi.展开更多
In recent years,magnesium and its alloys are considered as biodegradable implants.However magnesium implants may rapidly corrode before the natural healing process of the tissue is completed.In this investigation,micr...In recent years,magnesium and its alloys are considered as biodegradable implants.However magnesium implants may rapidly corrode before the natural healing process of the tissue is completed.In this investigation,micro arc oxidation process has been studied for avoiding primary corrosion of the magnesium alloy in simulated body fluid.Anodized coating was formed on AZ31 alloy in nontoxic silicate-alkaline solution at constant current.The effects of silicate concentration and conductivity of electrolyte solution on microstructure and corrosion properties of coating were evaluated.Scanning electron microscopy showed that a thick and condensed coating is formed after enough anodizing period.Energy dispersive spectroscopy showed that Si,O and Mg are the main components of the coating.Corrosion resistance of the coated and uncoated samples was assessed using potentiodynamic polarization and electrochemical impedance spectroscopy tests in SBF at 37℃ and pH of 7.4.Maximum corrosion resistance was achieved at 30 g/L concentration of sodium silicate in anodizing solution.It was observed that further increase in silicate concentration decreased the corrosion resistance.展开更多
The effects of Zn content on the microstxucture and the mechanical and corrosion properties of as-cast low-alloyed Mg-xZn~.2Ca alloys (x = 0.6wt%, 2.0wt%, 2.5wt%, hereafter denoted as 0.6Zn, 2.0Zn, and 2.5Zn alloys, ...The effects of Zn content on the microstxucture and the mechanical and corrosion properties of as-cast low-alloyed Mg-xZn~.2Ca alloys (x = 0.6wt%, 2.0wt%, 2.5wt%, hereafter denoted as 0.6Zn, 2.0Zn, and 2.5Zn alloys, respectively) axe investigated. The results show that the Zn content not only influences grain refinement but also induces different phase precipitation behaviors. The as-cast microstxucture of the 0.6Zn alloy is composed of ct-Mg, Mg2Ca, and Ca2Mg6Zn3 phases, whereas 2.0Zn and 2.5Zn alloys only contain ct-Mg and Ca2Mg6Zn3 phases, as revealed by X-ray diffraction (XRD) and txonsmission electron microscopy (TEM) analyses. Moreover, with in- creasing Zn content, both the ultimate tensile strength (UTS) and the elongation to fracture first increase and then decrease. Among the three investigated alloys, the largest UTS (178 MPa) and the highest elongation to fracture (6.5%) are obtained for the 2.0Zn alloy. In addition, the corrosion rate increases with increasing Zn content. This paper provides on updated investigation of the alloy composi- tion-microstxucture-property relationships of different Zn-containing Mg-Zn-Ca alloys.展开更多
Surface preparation is potentially important to the corrosion and biomedical properties of NiTi shape memory alloys. The effect of surface preparation on corrosion properties and nickel release of a Ti-56 wt.%Ni alloy...Surface preparation is potentially important to the corrosion and biomedical properties of NiTi shape memory alloys. The effect of surface preparation on corrosion properties and nickel release of a Ti-56 wt.%Ni alloy has been studied. Surface of the NiTi coupons were prepared by four methods, namely, chemical etching, electropolishing, mechanical polishing and oxidizing, and then examined by corrosion test system. Furthermore, the Ni ion releases from NiTi samples with different surface preparations dipped in 1% HCl solution were analysed. Compared with the surface after chemical treatment, mechanical polishing and thermal oxidation, electropolished surface has better corrosion resistance and less nickel release for not only its lower surface roughness, but also the composition and property of its surface film.展开更多
Base metals of domestic pipeline steels were used to study the effect of Mn on corrosion properties of SSCC(Sulfide Stress Corrosion Cracking), and welds were carried out to study the effect of MnS on corrosion proper...Base metals of domestic pipeline steels were used to study the effect of Mn on corrosion properties of SSCC(Sulfide Stress Corrosion Cracking), and welds were carried out to study the effect of MnS on corrosion properties of HIC (Hydrogen Induced Cracking) both in solutions with wet hydrogen sulfide(H_2S). They were respectively conducted by referring to the standards of SSCC and HIC. Testing results revealed that with the increase of content Mn, the resistance of SSCC will be decreased, from the point of metallurgic view, and it is Mn element not C element to lead to the testing results of SSCC. Meanwhile, even under the condition without inclusions MnS, HIC in welds still occurred. That is to say, MnS is not necessary for HIC, the presence of local banded structures in which Mn and P are inclined to aggregate cause to the phenomena of HIC.展开更多
Magnesium(Mg)and its alloys have received much attention in a lot of areas due to their special chemical and physical properties.Nevertheless,high corrosion rates are a limiting factor.The plasma electrolytic oxidatio...Magnesium(Mg)and its alloys have received much attention in a lot of areas due to their special chemical and physical properties.Nevertheless,high corrosion rates are a limiting factor.The plasma electrolytic oxidation(PEO)technique is a simple approach to place an oxide film on the surface of light metals like Mg alloys.This method has been considered for controlling the rate of corrosion and improving some other properties.On the other hand,PEO coatings cannot make enough protection of Magnesium alloys for a long time due to porosity and fine cracks.Therefore,PEO-based composite coatings are used to make adequate corrosion protection on the Mg alloys surface.The popularity of these coatings is due to their good corrosion resistance,simplicity,high coating capability,and cost-effectiveness in complex segments.Formation of an organic layer on the surface of PEO coating is one of the effective methods to close the defects and thus prevent the corrosive species penetration into the substrate.Coating the PEO coating with a polymer layer can be a good solution to control the amount of damage and improve the corrosion and abrasion resistance.In addition,PEO coating can eliminate the problems of insufficient adhesion of polymer coatings and is considered as a suitable base for composite coatings.This review paper presents the corrosion and abrasion behavior of the PEO/Polymer dual coating system on Mg alloys.Given the fundamental role of coatings thickness and morphology in wear and corrosion behavior,these aspects have been highly discussed in this study.展开更多
The influence of chemical composition on corrosion resistance of AZ91D magnesium alloys ingots has been investigated. Mass loss method was applied to evaluate the corrosion resistance of AZ91D alloys and the data were...The influence of chemical composition on corrosion resistance of AZ91D magnesium alloys ingots has been investigated. Mass loss method was applied to evaluate the corrosion resistance of AZ91D alloys and the data were analyzed by multiple regression. The results show that the corrosion resistance of this alloy can be improved by increasing Al, Zn and Mn in a certain degree, and will drop with increasing Si and heavy metals (Fe, Cu, Ni). It is found that ingots received from company F should be listed into unusable materials in terms of the corrosion resistance, while among the five suppliers, the only local company E supplied excellent AZ91D magnesium alloy ingots with the best corrosion resistance.展开更多
The relationship of corrosion resistance and antifouling behavior of 19 Cu alloys exposed to seawater of Qingdao ,Xiamen,Yulin sea areas in China for 1,2,4,8 year intervals was studied .The experiments were carried on...The relationship of corrosion resistance and antifouling behavior of 19 Cu alloys exposed to seawater of Qingdao ,Xiamen,Yulin sea areas in China for 1,2,4,8 year intervals was studied .The experiments were carried on by analyzing the composition of corrosion films formed on the surface of alloy specimens during the immersion time and by using OM,SEM,EDXA and AES experiment methods.The results verify the view point that it is the cuprous oxide film which played an important role in antifouling property of Cu alloys in seawater and throw a light on the view point in details further.The influence of different sea areas on the antifouling property of Cu alloys is also discussed.展开更多
Magnesium(Mg)alloys are promising materials for cardiovascular stent applications due to their good biocompatibility and biodegradability.However,in vitro and in vivo corrosion tests reveal that Mg alloy stents suffer...Magnesium(Mg)alloys are promising materials for cardiovascular stent applications due to their good biocompatibility and biodegradability.However,in vitro and in vivo corrosion tests reveal that Mg alloy stents suffer from a rapid corrosion rate and severe localized corrosion,which is limiting their widespread application.To solve the problem of uneven degradation of stents,a HTHE(long-time and high-temperature heat treatment,large-reduction-ratio hot extrusion)process is used to manufacture Mg-Zn-Y-Nd alloy microtubes in this study.The heat treatment is to dissolve alloying elements and reduce the size of SPPs,and the hot extrusion is to acquire fine-grained and strongly textured microtubes.The microstructural characterization shows that coarse second phases in as-cast alloy are refined and uniformly distributed in matrix of microtubes.After hot extrusion,microtubes show strong texture with basal plain oriented parallel to the longitudinal section(LS).The corrosion testing indicates that severe localized corrosion occurs on the cross section(CS)while localized corrosion is alleviated on the LS.Based on the different corrosion properties of the LS and CS,HTHEed microtubes are promising for solving the problems of rapid corrosion rate and severe localized corrosion of Mg alloy stents.展开更多
A two-step equal channel angular extrusion(ECAE) procedure was used to process pure Mg. The effects of ECAE processing temperature on the microstructure, mechanical properties, and corrosion behavior of pure Mg were...A two-step equal channel angular extrusion(ECAE) procedure was used to process pure Mg. The effects of ECAE processing temperature on the microstructure, mechanical properties, and corrosion behavior of pure Mg were studied. The results show that the average grain size of pure Mg decreases with decreasing extrusion temperature. After ECAE processing at 473 K, fine and equiaxed grains(~9 μm) are obtained. The sample processed at 473 K exhibits the excellent mechanical properties, whereas the sample processed at 633 K has the lowest corrosion rate. The improved corrosion resistance and mechanical properties of pure Mg by ECAE are ascribed to grain refinement and microstructural modification.展开更多
A new kind of corrosion resistant steelfor cargo oiltanks(COT)was developed.The influences of finalrolling temperature,cooling rate,and finalcooling temperature on microstructure were investigated.The proper rolling...A new kind of corrosion resistant steelfor cargo oiltanks(COT)was developed.The influences of finalrolling temperature,cooling rate,and finalcooling temperature on microstructure were investigated.The proper rolling process parameters were obtained through multi-pass thermalsimulation test.The finalrolling temperature is about 820 ℃,the finalcooling temperature is about 600 ℃,and the cooling rate should be controlled between 10 ℃/s and 20 ℃/s.Based on the above analysis of the results,three groups of rolling samples by thermo mechanicalcontrolprocess are prepared.The tensile strength,yield strength,and toughness of the corrosion resistant steelare measured,which meet the requirements of DH36 steel,it can instruct the actualrolling production.The corrosion behaviour is also researched by weight loss and electrochemicalimpedance spectroscopic method,and it is found that the steelhas good corrosion resistance performance,the best one is No.3 steel,the corrosion rate of which is about 1/4 of the accepted criterion.展开更多
The present study investigates the corrosion behavior of a Mg–Zn–Ca–La alloy.Results indicate that the corrosion resistance is enhanced by rolling deformation and subsequent annealing treatment significantly.The mi...The present study investigates the corrosion behavior of a Mg–Zn–Ca–La alloy.Results indicate that the corrosion resistance is enhanced by rolling deformation and subsequent annealing treatment significantly.The microstructure,distribution of second phase and grain orientation are the main factors affecting corrosion properties.The second phase with semi-continuous network in the as-cast alloy gives rise to the penetration of corrosion into the matrix.However,the dispersed second phase after deformation results in uniform corrosion.The formation of dense corrosion layer at the initial stage of corrosion is favorable for the improvement of corrosion resistance.The sample with<0001>plane oriented towards surface exhibits good corrosion resistance,which is ascribed to the homogeneous microstructure and strong basal texture.展开更多
This paper summarizes the corrosion behavior of Inconel 718 alloy, which is used in the oil and gas fields, including its uniform corrosion, pitting, intergranular corrosion, galvanic corrosion, stress corrosion, and ...This paper summarizes the corrosion behavior of Inconel 718 alloy, which is used in the oil and gas fields, including its uniform corrosion, pitting, intergranular corrosion, galvanic corrosion, stress corrosion, and hydrogen embrittlement. It also analyzes the main reasons for the good corrosion resistance of Inconel 718 alloy. This paper focuses on the effects of the heat-treatment process on corrosive behavior and provides guidelines for reasonable heat treatments in security service environments. Finally, this paper recommends further studies and applications of Inconel 718 in corrosion environments with high-temperature,high-pressure, and wet H2 S.展开更多
The microstructure and phase evolution of Mg-10.16Li-8.14Al-1.46Er alloy of as-cast,250℃+12 h,300℃+12 h,and 400℃+12 h were studied by optical microscopy,scanning electron microscope,and X-ray diffraction.The mechan...The microstructure and phase evolution of Mg-10.16Li-8.14Al-1.46Er alloy of as-cast,250℃+12 h,300℃+12 h,and 400℃+12 h were studied by optical microscopy,scanning electron microscope,and X-ray diffraction.The mechanical properties of Mg-10.16Li-8.14Al-1.46Er alloy in different states were tested by microhardness tester and tension tester.The corrosion resistance of Mg-10.16Li-8.14Al-1.46Er alloy in different states was measured by electrochemical workstation combined with hydrogen evolution and mass loss tests.The results show that the microstructure of as-cast Mg-10.16Li-8.14Al-1.46Er alloy consists ofα,β,AlLi,Al3Er and MgAlLi_(2)phases.Changes of microstructure are morphology and quantity ofαphase,and second phases of MgAlLi_(2)and AlLi by heat treatments at different temperatures.The best comprehensive tensile properties of Mg-10.16Li-8.14Al-1.46Er at 400℃are attributed to theαphase structure,solution strengthening and second phase strengthening.After heat treatments at different temperatures,the corrosion resistance of Mg-10.16Li-8.14Al-1.46Er was improved compared with as-cast samples.The Mg-10.16Li-8.14Al-1.46Er alloy has the best corrosion resistance at 250℃due to the best homogenization at this temperature.展开更多
Magnesium and its alloys have such advantages with lightweight, high specific strength, good damping, high castability and machinability,which make them an attractive choice for applications where weight reduction is ...Magnesium and its alloys have such advantages with lightweight, high specific strength, good damping, high castability and machinability,which make them an attractive choice for applications where weight reduction is important, such as in the aerospace and automotive industries.However, their practical applications are still limited because of their poor corrosion resistance, low high temperature strength and ambient formability. Based on such their property shortcomings, recently degradable magnesium alloys were developed for broadening their potential applications. Considering the degradable Mg alloys for medical applications were well reviewed, the present review put an emphasis on such degradable magnesium alloys for structural and functional applications, especially the applications in the environmental and energy fields. Their applications as fracture ball in fossil energy, sacrificial anode, washing ball, and as battery anodes, transient electronics, were summarized. The roles of alloying elements in magnesium and the design concept of such degradable magnesium alloys were discussed. The existing challenges for extending their future applications are explored.展开更多
Medium-manganese(Mn)steel(MMS)has remarkable characteristics of high strength,strong work-hardening capacity,and wear resistance,being a promising third-generation advanced high-strength steel with lower raw material ...Medium-manganese(Mn)steel(MMS)has remarkable characteristics of high strength,strong work-hardening capacity,and wear resistance,being a promising third-generation advanced high-strength steel with lower raw material cost compared with other generations of advanced high-strength steel.The chemical composition and processing route play critical roles in determining the microstructural evolution of the MMS,and the microstructure composition significantly influences the mechanical,corrosion and wear properties of the steel.Hence,a lot of research work focus on exploring the direct relation between microstructural evolution and mechanical/corrosion/wear properties,and the progress has the following crucial aspects:(1)alloying design on the phase composition and carbide precipitation,(2)processing route on regulating microstructure evolution and twinning-induced plasticity and/or transformation-induced plasticity strengthening mechanism,(3)work-hardening,corrosion,and corrosion resistance of the regulated MMS,and(4)fracture and failure mechanism of MMS under tensile,corrosion and wear damages,as well as the improvement strategies.展开更多
基金financially supported by the National Key Research and Development Program of China(No.2016YFB0701202,No.2017YFB0701500 and No.2020YFB1505901)National Natural Science Foundation of China(General Program No.51474149,52072240)+3 种基金Shanghai Science and Technology Committee(No.18511109300)Science and Technology Commission of the CMC(2019JCJQZD27300)financial support from the University of Michigan and Shanghai Jiao Tong University joint funding,China(AE604401)Science and Technology Commission of Shanghai Municipality(No.18511109302).
文摘Magnesium(Mg)alloys have shown great prospects as both structural and biomedical materials,while poor corrosion resistance limits their further application.In this work,to avoid the time-consuming and laborious experiment trial,a high-throughput computational strategy based on first-principles calculations is designed for screening corrosion-resistant binary Mg alloy with intermetallics,from both the thermodynamic and kinetic perspectives.The stable binary Mg intermetallics with low equilibrium potential difference with respect to the Mg matrix are firstly identified.Then,the hydrogen adsorption energies on the surfaces of these Mg intermetallics are calculated,and the corrosion exchange current density is further calculated by a hydrogen evolution reaction(HER)kinetic model.Several intermetallics,e.g.Y_(3)Mg,Y_(2)Mg and La_(5)Mg,are identified to be promising intermetallics which might effectively hinder the cathodic HER.Furthermore,machine learning(ML)models are developed to predict Mg intermetallics with proper hydrogen adsorption energy employing work function(W_(f))and weighted first ionization energy(WFIE).The generalization of the ML models is tested on five new binary Mg intermetallics with the average root mean square error(RMSE)of 0.11 eV.This study not only predicts some promising binary Mg intermetallics which may suppress the galvanic corrosion,but also provides a high-throughput screening strategy and ML models for the design of corrosion-resistant alloy,which can be extended to ternary Mg alloys or other alloy systems.
基金the financial support provided by the Australian Research Council(ARC)through the Future Fellowship(FT160100252)the Discovery Project(DP170102557)for this research。
文摘Magnesium(Mg)-based bone implants degrade rapidly in the physiological environment of the human body which affects their structural integrity and biocompatibility before adequate bone repair.Rare earth elements(REEs)have demonstrated their effectiveness in tailoring the corrosion and mechanical behavior of Mg alloys.This study methodically investigated the impacts of scandium(Sc)and terbium(Tb)in tailoring the corrosion resistance,mechanical properties,and biocompatibility of Mg–0.5Zn–0.35Zr–0.15Mn(MZZM)alloys fabricated via casting and hot extrusion.Results indicate that addition of Sc and Tb improved the strength of MZZM alloys via grain size reduction and solid solution strengthening mechanisms.The extruded MZZM–(1–2)Sc–(1–2)Tb(wt.%)alloys exhibit compressive strengths within the range of 336–405 MPa,surpassing the minimum required strength of 200 MPa for bone implants by a significant margin.Potentiodynamic polarization tests revealed low corrosion rates of as–cast MZZM(0.25 mm/y),MZZM–2Tb(0.45 mm/y),MZZM–1Sc–1Tb(0.18 mm/y),and MZZM–1Sc–2Tb(0.64 mm/y),and extruded MZZM(0.17 mm/y),MZZM–1Sc(0.15 mm/y),MZZM-2Sc(0.45 mm/y),MZZM-1Tb(0.17 mm/y),MZZM-2Tb(0.10 mm/y),MZZM–1Sc-1Tb(0.14 mm/y),MZZM-1Sc-2Tb(0.40 mm/y),and MZZM–2Sc–2Tb(0.51 mm/y)alloys,which were found lower compared to corrosion rate of high-purity Mg(~1.0 mm/y)reported in the literature.Furthermore,addition of Sc,or Tb,or Sc and Tb to MZZM alloys did not adversely affect the viability of SaOS2 cells,but enhanced their initial cell attachment,proliferation,and spreading shown via polygonal shapes and filipodia.This study emphasizes the benefits of incorporating Sc and Tb elements in MZZM alloys,as they effectively enhance corrosion resistance,mechanical properties,and biocompatibility simultaneously.
文摘By means of surface mechanical attrition treatment ( SMAT), the groin size with a diameter of aboat 60hm formed at about 20μm depth and numerous mechanical twins at about 50μm depth from the treated surface were synthesized in 316L stainless steel because of the different distributions of strain and strain rate along depth orientation. For instance the maximum strain rate reached 10^3-10^4s^-1 on the top surface. The relationship between the microsturcture and the corrosion property was studied in 0.05M H2SO4+ 0.25M Na2SO4 aqueous solution, and the results show an extreme improvement of corrosion resistance owing to the appearance of twin boundaries and the obvious reduction in corrosion resistance attributed to the presence of nanocrystaline boundaries.
文摘A new model considering corrosion property for grounding grids diagnosis is proposed,which provides reference solutions of ambiguous branches.The constraint total least square method based on singular value decomposition is adopted to improve the effectiveness of grounding grids' diagnosis algorithm.The improvement can weaken the influence of the model's error,which results from the differences between design paper and actual grid.Its influence on touch and step voltages caused by the interior resistance of conductors is taken into account.Simulation results show the validity of this approach.
基金Project supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.KJCX2-YW-N35 and XDA03010303)the National Natural Science Foundation of China(Grant Nos.91026002 and 91126002)the National Magnetic Confinement Fusion Program,China(Grant No.2011GB108004)
文摘The corrosion of steels in liquid metal lead (Pb) and bismuth (Bi) is a critical challenge in the development of accel-erator driven systems (ADS). Using a first-principles method with a slab model, we theoretically investigate the interaction between the Pb (Bi) atom and the iron (Fe) (100) surface to assess the fundamental corrosion properties. Our investigation demonstrates that both Pb and Bi atoms favorably adsorb on the (100) surface. Such an adsorption decreases the energy required for the dissociation of an Fe atom from the surface, enhancing the dissolution tendency significantly. The seg- regation of six common alloying elements (Cr, A1, Mn, Ni, Nb, and Si) to the surface and their impacts on the corrosion properties are also considered. The present results reveal that Si seems to have a relatively good performance to stabilize the surface and alleviate the dissolving trend caused by Pb and Bi.
文摘In recent years,magnesium and its alloys are considered as biodegradable implants.However magnesium implants may rapidly corrode before the natural healing process of the tissue is completed.In this investigation,micro arc oxidation process has been studied for avoiding primary corrosion of the magnesium alloy in simulated body fluid.Anodized coating was formed on AZ31 alloy in nontoxic silicate-alkaline solution at constant current.The effects of silicate concentration and conductivity of electrolyte solution on microstructure and corrosion properties of coating were evaluated.Scanning electron microscopy showed that a thick and condensed coating is formed after enough anodizing period.Energy dispersive spectroscopy showed that Si,O and Mg are the main components of the coating.Corrosion resistance of the coated and uncoated samples was assessed using potentiodynamic polarization and electrochemical impedance spectroscopy tests in SBF at 37℃ and pH of 7.4.Maximum corrosion resistance was achieved at 30 g/L concentration of sodium silicate in anodizing solution.It was observed that further increase in silicate concentration decreased the corrosion resistance.
基金supported by the National Natural Science Foundation of China(No.51671017)Fundamental Research Funds for the Central Universities(No.FRF-GF-17-B3)+1 种基金Beijing Laboratory of Metallic Materials and Processing for Modern Transportation,the Opening Research Fund of State Key Laboratory for Advanced Metals and Materials(Nos.2016Z-11,2017Z-08)State's Key Project of Research and Development Plan(No.2016YFB0300801)
文摘The effects of Zn content on the microstxucture and the mechanical and corrosion properties of as-cast low-alloyed Mg-xZn~.2Ca alloys (x = 0.6wt%, 2.0wt%, 2.5wt%, hereafter denoted as 0.6Zn, 2.0Zn, and 2.5Zn alloys, respectively) axe investigated. The results show that the Zn content not only influences grain refinement but also induces different phase precipitation behaviors. The as-cast microstxucture of the 0.6Zn alloy is composed of ct-Mg, Mg2Ca, and Ca2Mg6Zn3 phases, whereas 2.0Zn and 2.5Zn alloys only contain ct-Mg and Ca2Mg6Zn3 phases, as revealed by X-ray diffraction (XRD) and txonsmission electron microscopy (TEM) analyses. Moreover, with in- creasing Zn content, both the ultimate tensile strength (UTS) and the elongation to fracture first increase and then decrease. Among the three investigated alloys, the largest UTS (178 MPa) and the highest elongation to fracture (6.5%) are obtained for the 2.0Zn alloy. In addition, the corrosion rate increases with increasing Zn content. This paper provides on updated investigation of the alloy composi- tion-microstxucture-property relationships of different Zn-containing Mg-Zn-Ca alloys.
文摘Surface preparation is potentially important to the corrosion and biomedical properties of NiTi shape memory alloys. The effect of surface preparation on corrosion properties and nickel release of a Ti-56 wt.%Ni alloy has been studied. Surface of the NiTi coupons were prepared by four methods, namely, chemical etching, electropolishing, mechanical polishing and oxidizing, and then examined by corrosion test system. Furthermore, the Ni ion releases from NiTi samples with different surface preparations dipped in 1% HCl solution were analysed. Compared with the surface after chemical treatment, mechanical polishing and thermal oxidation, electropolished surface has better corrosion resistance and less nickel release for not only its lower surface roughness, but also the composition and property of its surface film.
文摘Base metals of domestic pipeline steels were used to study the effect of Mn on corrosion properties of SSCC(Sulfide Stress Corrosion Cracking), and welds were carried out to study the effect of MnS on corrosion properties of HIC (Hydrogen Induced Cracking) both in solutions with wet hydrogen sulfide(H_2S). They were respectively conducted by referring to the standards of SSCC and HIC. Testing results revealed that with the increase of content Mn, the resistance of SSCC will be decreased, from the point of metallurgic view, and it is Mn element not C element to lead to the testing results of SSCC. Meanwhile, even under the condition without inclusions MnS, HIC in welds still occurred. That is to say, MnS is not necessary for HIC, the presence of local banded structures in which Mn and P are inclined to aggregate cause to the phenomena of HIC.
文摘Magnesium(Mg)and its alloys have received much attention in a lot of areas due to their special chemical and physical properties.Nevertheless,high corrosion rates are a limiting factor.The plasma electrolytic oxidation(PEO)technique is a simple approach to place an oxide film on the surface of light metals like Mg alloys.This method has been considered for controlling the rate of corrosion and improving some other properties.On the other hand,PEO coatings cannot make enough protection of Magnesium alloys for a long time due to porosity and fine cracks.Therefore,PEO-based composite coatings are used to make adequate corrosion protection on the Mg alloys surface.The popularity of these coatings is due to their good corrosion resistance,simplicity,high coating capability,and cost-effectiveness in complex segments.Formation of an organic layer on the surface of PEO coating is one of the effective methods to close the defects and thus prevent the corrosive species penetration into the substrate.Coating the PEO coating with a polymer layer can be a good solution to control the amount of damage and improve the corrosion and abrasion resistance.In addition,PEO coating can eliminate the problems of insufficient adhesion of polymer coatings and is considered as a suitable base for composite coatings.This review paper presents the corrosion and abrasion behavior of the PEO/Polymer dual coating system on Mg alloys.Given the fundamental role of coatings thickness and morphology in wear and corrosion behavior,these aspects have been highly discussed in this study.
文摘The influence of chemical composition on corrosion resistance of AZ91D magnesium alloys ingots has been investigated. Mass loss method was applied to evaluate the corrosion resistance of AZ91D alloys and the data were analyzed by multiple regression. The results show that the corrosion resistance of this alloy can be improved by increasing Al, Zn and Mn in a certain degree, and will drop with increasing Si and heavy metals (Fe, Cu, Ni). It is found that ingots received from company F should be listed into unusable materials in terms of the corrosion resistance, while among the five suppliers, the only local company E supplied excellent AZ91D magnesium alloy ingots with the best corrosion resistance.
文摘The relationship of corrosion resistance and antifouling behavior of 19 Cu alloys exposed to seawater of Qingdao ,Xiamen,Yulin sea areas in China for 1,2,4,8 year intervals was studied .The experiments were carried on by analyzing the composition of corrosion films formed on the surface of alloy specimens during the immersion time and by using OM,SEM,EDXA and AES experiment methods.The results verify the view point that it is the cuprous oxide film which played an important role in antifouling property of Cu alloys in seawater and throw a light on the view point in details further.The influence of different sea areas on the antifouling property of Cu alloys is also discussed.
基金financial support of Key Projects of the Joint Fund of the National Natural Science Foundation of China(Grant No:U1804251)the National Key Research and Development Program of China(2016YFC1102403,2018YFC1106703 and 2017YFB0702504)+1 种基金China Scholarship Council for the award of fellowship and funding(No.201707040058)China Scholarship Council for the award of fellowship and funding(No.201607040051)。
文摘Magnesium(Mg)alloys are promising materials for cardiovascular stent applications due to their good biocompatibility and biodegradability.However,in vitro and in vivo corrosion tests reveal that Mg alloy stents suffer from a rapid corrosion rate and severe localized corrosion,which is limiting their widespread application.To solve the problem of uneven degradation of stents,a HTHE(long-time and high-temperature heat treatment,large-reduction-ratio hot extrusion)process is used to manufacture Mg-Zn-Y-Nd alloy microtubes in this study.The heat treatment is to dissolve alloying elements and reduce the size of SPPs,and the hot extrusion is to acquire fine-grained and strongly textured microtubes.The microstructural characterization shows that coarse second phases in as-cast alloy are refined and uniformly distributed in matrix of microtubes.After hot extrusion,microtubes show strong texture with basal plain oriented parallel to the longitudinal section(LS).The corrosion testing indicates that severe localized corrosion occurs on the cross section(CS)while localized corrosion is alleviated on the LS.Based on the different corrosion properties of the LS and CS,HTHEed microtubes are promising for solving the problems of rapid corrosion rate and severe localized corrosion of Mg alloy stents.
基金financially supported by the National Natural Science Foundation of China (Nos. 81330031 and 81271701)
文摘A two-step equal channel angular extrusion(ECAE) procedure was used to process pure Mg. The effects of ECAE processing temperature on the microstructure, mechanical properties, and corrosion behavior of pure Mg were studied. The results show that the average grain size of pure Mg decreases with decreasing extrusion temperature. After ECAE processing at 473 K, fine and equiaxed grains(~9 μm) are obtained. The sample processed at 473 K exhibits the excellent mechanical properties, whereas the sample processed at 633 K has the lowest corrosion rate. The improved corrosion resistance and mechanical properties of pure Mg by ECAE are ascribed to grain refinement and microstructural modification.
基金Funded by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China during the“12th Five-Year Plan”(No.2011BAE25B03)
文摘A new kind of corrosion resistant steelfor cargo oiltanks(COT)was developed.The influences of finalrolling temperature,cooling rate,and finalcooling temperature on microstructure were investigated.The proper rolling process parameters were obtained through multi-pass thermalsimulation test.The finalrolling temperature is about 820 ℃,the finalcooling temperature is about 600 ℃,and the cooling rate should be controlled between 10 ℃/s and 20 ℃/s.Based on the above analysis of the results,three groups of rolling samples by thermo mechanicalcontrolprocess are prepared.The tensile strength,yield strength,and toughness of the corrosion resistant steelare measured,which meet the requirements of DH36 steel,it can instruct the actualrolling production.The corrosion behaviour is also researched by weight loss and electrochemicalimpedance spectroscopic method,and it is found that the steelhas good corrosion resistance performance,the best one is No.3 steel,the corrosion rate of which is about 1/4 of the accepted criterion.
基金the National Natural Science Foundation of China(No.51801150)Shaanxi Natural Science Basic Research Program(No.2019JQ-512)Shaanxi Provincial Department of Education Fund(No.16JK1557).
文摘The present study investigates the corrosion behavior of a Mg–Zn–Ca–La alloy.Results indicate that the corrosion resistance is enhanced by rolling deformation and subsequent annealing treatment significantly.The microstructure,distribution of second phase and grain orientation are the main factors affecting corrosion properties.The second phase with semi-continuous network in the as-cast alloy gives rise to the penetration of corrosion into the matrix.However,the dispersed second phase after deformation results in uniform corrosion.The formation of dense corrosion layer at the initial stage of corrosion is favorable for the improvement of corrosion resistance.The sample with<0001>plane oriented towards surface exhibits good corrosion resistance,which is ascribed to the homogeneous microstructure and strong basal texture.
文摘This paper summarizes the corrosion behavior of Inconel 718 alloy, which is used in the oil and gas fields, including its uniform corrosion, pitting, intergranular corrosion, galvanic corrosion, stress corrosion, and hydrogen embrittlement. It also analyzes the main reasons for the good corrosion resistance of Inconel 718 alloy. This paper focuses on the effects of the heat-treatment process on corrosive behavior and provides guidelines for reasonable heat treatments in security service environments. Finally, this paper recommends further studies and applications of Inconel 718 in corrosion environments with high-temperature,high-pressure, and wet H2 S.
基金funded by the National Natural Science Foundation of China(No.51801185)Key Research Project of the Higher Education Institutions of Henan Province,Henan Provincial Department of Education,China(No.19A460007)TrainingProgram for Young Backbone Teachers of the Higher Education Institutions of Henan Province,China.
文摘The microstructure and phase evolution of Mg-10.16Li-8.14Al-1.46Er alloy of as-cast,250℃+12 h,300℃+12 h,and 400℃+12 h were studied by optical microscopy,scanning electron microscope,and X-ray diffraction.The mechanical properties of Mg-10.16Li-8.14Al-1.46Er alloy in different states were tested by microhardness tester and tension tester.The corrosion resistance of Mg-10.16Li-8.14Al-1.46Er alloy in different states was measured by electrochemical workstation combined with hydrogen evolution and mass loss tests.The results show that the microstructure of as-cast Mg-10.16Li-8.14Al-1.46Er alloy consists ofα,β,AlLi,Al3Er and MgAlLi_(2)phases.Changes of microstructure are morphology and quantity ofαphase,and second phases of MgAlLi_(2)and AlLi by heat treatments at different temperatures.The best comprehensive tensile properties of Mg-10.16Li-8.14Al-1.46Er at 400℃are attributed to theαphase structure,solution strengthening and second phase strengthening.After heat treatments at different temperatures,the corrosion resistance of Mg-10.16Li-8.14Al-1.46Er was improved compared with as-cast samples.The Mg-10.16Li-8.14Al-1.46Er alloy has the best corrosion resistance at 250℃due to the best homogenization at this temperature.
文摘Magnesium and its alloys have such advantages with lightweight, high specific strength, good damping, high castability and machinability,which make them an attractive choice for applications where weight reduction is important, such as in the aerospace and automotive industries.However, their practical applications are still limited because of their poor corrosion resistance, low high temperature strength and ambient formability. Based on such their property shortcomings, recently degradable magnesium alloys were developed for broadening their potential applications. Considering the degradable Mg alloys for medical applications were well reviewed, the present review put an emphasis on such degradable magnesium alloys for structural and functional applications, especially the applications in the environmental and energy fields. Their applications as fracture ball in fossil energy, sacrificial anode, washing ball, and as battery anodes, transient electronics, were summarized. The roles of alloying elements in magnesium and the design concept of such degradable magnesium alloys were discussed. The existing challenges for extending their future applications are explored.
基金supported by the Innovation and Technology Fund(ITF)(ITP/020/20AP)the National Key Research and Development Program of China(2021YFB3701704)+2 种基金the Guangdong Academy of Sciences(GDAS)Project of Science and Technology Development(2022GDASZH-2022010103)Jiangxi Science and Technology Plan Project(S2020CXTD0356)the Young Talent Support Project of Guangzhou Association for Science and Technology(QT20220101075)。
文摘Medium-manganese(Mn)steel(MMS)has remarkable characteristics of high strength,strong work-hardening capacity,and wear resistance,being a promising third-generation advanced high-strength steel with lower raw material cost compared with other generations of advanced high-strength steel.The chemical composition and processing route play critical roles in determining the microstructural evolution of the MMS,and the microstructure composition significantly influences the mechanical,corrosion and wear properties of the steel.Hence,a lot of research work focus on exploring the direct relation between microstructural evolution and mechanical/corrosion/wear properties,and the progress has the following crucial aspects:(1)alloying design on the phase composition and carbide precipitation,(2)processing route on regulating microstructure evolution and twinning-induced plasticity and/or transformation-induced plasticity strengthening mechanism,(3)work-hardening,corrosion,and corrosion resistance of the regulated MMS,and(4)fracture and failure mechanism of MMS under tensile,corrosion and wear damages,as well as the improvement strategies.