Different stress states have a significant influence on the magnitude of the microscopic plastic strain and result in the development of the microstructure evolution.As a result,a comprehensive understanding of the di...Different stress states have a significant influence on the magnitude of the microscopic plastic strain and result in the development of the microstructure evolution.As a result,a comprehensive understanding of the different scale variation on microstructure evolution during bending deformation is essential.The advanced high strength dual-phase(DP1180)steel was investigated using multiscale microstructure-based 3D representative volume element(RVE)modelling technology with emphasis on understanding the relationship between the microstructure,localised stress-strain evolution as well as the deformation characteristics in the bending process.It is demonstrated that the localised development in bending can be more accurately described by microscopic deformation when taking into account microstructural properties.Microstructure-based 3D RVEs from each chosen bending condition generally have comparable localisation properties,whilst the magnitudes and intensities differ.In addition,the most severe localised bands are predicted to occur close to the ferrite and martensite phase boundaries where the martensite grains are close together or have a somewhat sharp edge.The numerically predicted results for the microstructure evolution,shear bands development and stress and strain distribution after 3-point bending exhibit a good agreement with the relevant experimental observations.展开更多
High entropy alloys(HEAs)attract remarkable attention due to the excellent mechanical performance.However,the origins of their high strength and toughness compared with those of the traditional alloys are still hardly...High entropy alloys(HEAs)attract remarkable attention due to the excellent mechanical performance.However,the origins of their high strength and toughness compared with those of the traditional alloys are still hardly revealed.Here,using a microstructure-based constitutive model and molecular dynamics(MD)simulation,we investigate the unique mechanical behavior and microstructure evolution of FeCoCrNiCu HEAs during the indentation.Due to the interaction between the dislocation and solution,the high dislocation density in FeCoCrNiCu leads to strong work hardening.Plentiful slip systems are stimulated,leading to the good plasticity of FeCoCrNiCu.The plastic deformation of FeCoCrNiCu is basically affected by the motion of dislocation loops.The prismatic dislocation loops inside FeCoCrNiCu are formed by the dislocations with the Burgers vectors of a/6[112]and a/6[112],which interact with each other,and then emit along the<111>slip direction.In addition,the mechanical properties of FeCoCrNiCu HEA can be predicted by constructing the microstructure-based constitutive model,which is identified according to the evolution of the dislocation density and the stress-strain curve.Strong dislocation strengthening and remarkable lattice distortion strengthening occur in the deformation process of FeCoCrNiCu,and improve the strength.Therefore,the origins of high strength and high toughness in FeCoCrNiCu HEAs come from lattice distortion strengthening and the more activable slip systems compared with Cu.These results accelerate the discovery of HEAs with excellent mechanical properties,and provide a valuable reference for the industrial application of HEAs.展开更多
High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicle...High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicles enhances structural reliability and cost efficiency.However,HPDC Mg alloys face challenges related to casting defects such as porosity,cold shuts,and oxides.These defects influence tensile strength and ductility,depending on their location and size.This study employs finite element(FE)modeling to investigate how a dominant large pore,its position,and the sample size affect the ductility of thin-walled HPDC Mg.Motivated by the ductility variations reported in literature and the experimental findings on AM60 castings,synthetic microstructure-based models are used to assess the effects of different pore sizes and locations.The results indicate the presence of three different regions based on the large pore size and model size:1)a region dominated by the effects of the large pore,2)a plateau region dominated by pore interactions,and 3)a transient region between these two effects.A threshold distance from the sample edge (d≈0.9√D·L)is proposed,within which a large pore can significantly reduce ductility.Additionally,large pores near edges contribute to ductility variations in Mg castings.展开更多
基金supported by HBIS Group under the Grant No.IRIS 200506003.
文摘Different stress states have a significant influence on the magnitude of the microscopic plastic strain and result in the development of the microstructure evolution.As a result,a comprehensive understanding of the different scale variation on microstructure evolution during bending deformation is essential.The advanced high strength dual-phase(DP1180)steel was investigated using multiscale microstructure-based 3D representative volume element(RVE)modelling technology with emphasis on understanding the relationship between the microstructure,localised stress-strain evolution as well as the deformation characteristics in the bending process.It is demonstrated that the localised development in bending can be more accurately described by microscopic deformation when taking into account microstructural properties.Microstructure-based 3D RVEs from each chosen bending condition generally have comparable localisation properties,whilst the magnitudes and intensities differ.In addition,the most severe localised bands are predicted to occur close to the ferrite and martensite phase boundaries where the martensite grains are close together or have a somewhat sharp edge.The numerically predicted results for the microstructure evolution,shear bands development and stress and strain distribution after 3-point bending exhibit a good agreement with the relevant experimental observations.
基金the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.51621004)the National Natural Science Foundation of China(Nos.12072109,51871092,and 11772122)。
文摘High entropy alloys(HEAs)attract remarkable attention due to the excellent mechanical performance.However,the origins of their high strength and toughness compared with those of the traditional alloys are still hardly revealed.Here,using a microstructure-based constitutive model and molecular dynamics(MD)simulation,we investigate the unique mechanical behavior and microstructure evolution of FeCoCrNiCu HEAs during the indentation.Due to the interaction between the dislocation and solution,the high dislocation density in FeCoCrNiCu leads to strong work hardening.Plentiful slip systems are stimulated,leading to the good plasticity of FeCoCrNiCu.The plastic deformation of FeCoCrNiCu is basically affected by the motion of dislocation loops.The prismatic dislocation loops inside FeCoCrNiCu are formed by the dislocations with the Burgers vectors of a/6[112]and a/6[112],which interact with each other,and then emit along the<111>slip direction.In addition,the mechanical properties of FeCoCrNiCu HEA can be predicted by constructing the microstructure-based constitutive model,which is identified according to the evolution of the dislocation density and the stress-strain curve.Strong dislocation strengthening and remarkable lattice distortion strengthening occur in the deformation process of FeCoCrNiCu,and improve the strength.Therefore,the origins of high strength and high toughness in FeCoCrNiCu HEAs come from lattice distortion strengthening and the more activable slip systems compared with Cu.These results accelerate the discovery of HEAs with excellent mechanical properties,and provide a valuable reference for the industrial application of HEAs.
基金funded by the Department of Energy Office of Vehicle Technologies under the Automotive Lightweighting Materials Program。
文摘High-pressure die-cast(HPDC)magnesium(Mg)and aluminum alloys enable vehicle lightweighting while reducing manufacturing costs by simplifying part assembly.The increasing use of super-large castings in electric vehicles enhances structural reliability and cost efficiency.However,HPDC Mg alloys face challenges related to casting defects such as porosity,cold shuts,and oxides.These defects influence tensile strength and ductility,depending on their location and size.This study employs finite element(FE)modeling to investigate how a dominant large pore,its position,and the sample size affect the ductility of thin-walled HPDC Mg.Motivated by the ductility variations reported in literature and the experimental findings on AM60 castings,synthetic microstructure-based models are used to assess the effects of different pore sizes and locations.The results indicate the presence of three different regions based on the large pore size and model size:1)a region dominated by the effects of the large pore,2)a plateau region dominated by pore interactions,and 3)a transient region between these two effects.A threshold distance from the sample edge (d≈0.9√D·L)is proposed,within which a large pore can significantly reduce ductility.Additionally,large pores near edges contribute to ductility variations in Mg castings.
