As one of the lightest engineering materials,magnesium(Mg)alloy possesses excellent mechanical performance,meeting the needs of versatile engineering fields and holding the potential to address cutting-edge issues in ...As one of the lightest engineering materials,magnesium(Mg)alloy possesses excellent mechanical performance,meeting the needs of versatile engineering fields and holding the potential to address cutting-edge issues in aerospace,electronics,biomedicine.The design of superhydrophobic(SHB)surfaces with micro and nanostructures can endow Mg alloys with multiple functionalities,such as self-cleaning,self-healing,antibacterial,and corrosion resistance.Over the past decade,researchers have drawn inspiration from nature to implement biomimetic design principles,resulting in the rapid development of micro/nanostructured SHB surfaces on Mg alloys,which hold great promise for biomedical applications.This review comprehensively introduces the biomimetic design principles of micro/nanostructured SHB surfaces on Mg alloys,discusses the challenges along with advantages and disadvantages of current preparation methods,and explores the future perspectives for preparing these SHB surfaces,providing strategies to enhance their performance in biomedical applications.展开更多
Critical engineering applications,such as landing gears and armor protection,require structural materials withstanding high strength and significant plastic deformation.Nanoprecipitate-strengthened high-entropy alloys...Critical engineering applications,such as landing gears and armor protection,require structural materials withstanding high strength and significant plastic deformation.Nanoprecipitate-strengthened high-entropy alloys(HEAs)are considered as promising candidates for structural applications due to their enhanced strength and exceptional work-hardening capability.Herein,we report a FeCoNiAlTi-type HEA that achieves ultrahigh gigapascal yield strength from quasi-static to dynamic loading conditions and superb resistance to adiabatic shear failure.This is accomplished by introducing high-density coherent L1_(2) nanoprecipitates.Multiscale characterization and molecular dynamics simulation demonstrate that the L1_(2) nanoprecipitates exhibit multiple functions during impact,not only as the dislocation barrier and the dislocation transmission medium,but also as energyabsorbing islands that disperse the stress spikes through order-to-disorder transition,which result in extraordinary impact resistance.These findings shed light on the development of novel impact-resistant metallic materials.展开更多
Selective laser melting(SLM)has the advantage in preparing supersaturated solid solutions due to its unique thermal field and high solidification rate.In this study,a face-centered cubic single-phase FeCrNi medium ent...Selective laser melting(SLM)has the advantage in preparing supersaturated solid solutions due to its unique thermal field and high solidification rate.In this study,a face-centered cubic single-phase FeCrNi medium entropy alloy(MEA)with an ultrahigh Cr content(~35 at.%)was additively manufactured by SLM.The as-built MEA shows a hierarchical microstructure of coarse columnar grains and submicron dislocation cell structures,where the cell boundaries are probed segregated with Cr and C and decorated with nano carbides.The appearance of these dislocation barriers results in an excellent combination of strength(σ_(0.2)=745 MPa,σ_(UTS)=1007 MPa)and ductility(ε_(f)=31%).The current MEA also shows a superb corrosion resistance with a corrosion current density of 0.06μA cm^(−2) in 3.5 wt.%NaCl solution,which is far lower than that of 316 L.The high content of solutioned Cr in the MEA ensures sufficient Cr supply to form an integrated Cr_(2)O_(3) passive film,and the large number of cell boundaries acting as the diffusion channels lead to the fast formation of a stable passive film over the alloy surface.展开更多
The mechanical properties of refractory high entropy alloys(RHEAs) strongly depend on their phase structures. In this work, the phase stability of a BCC TiNbTa0.5ZrAl0.5 refractory high entropy alloy subjected to ther...The mechanical properties of refractory high entropy alloys(RHEAs) strongly depend on their phase structures. In this work, the phase stability of a BCC TiNbTa0.5ZrAl0.5 refractory high entropy alloy subjected to thermomechanical processing was evaluated, and the effects of phase decomposition on room/high temperature mechanical properties were quantitatively studied. It was found that, the thermomechanical processing at 800℃and 1200℃ leads to phase decomposition in the TiNbTa0.5ZrAl0.5 alloy. The phase decomposition is caused by the rapid rising of free energy of the primary BCC phase. The effect of the precipitates on room temperature strength is determined by the competition between the increasing in precipitation strengthening and the decreasing in solid solution strengthening. But at high temperatures(800-1200℃), the phase decomposition causes significant reduction in strength, mainly due to the grain boundary sliding and the decreasing in solid solution strengthening.展开更多
A novel cobalt-free oxide dispersion strengthened(ODS)equiatomic FeCrNi medium entropy alloy(MEA)was successfully fabricated through mechanical alloying and hot extrusion(HE).The ODS FeCrNi MEA is composed of a single...A novel cobalt-free oxide dispersion strengthened(ODS)equiatomic FeCrNi medium entropy alloy(MEA)was successfully fabricated through mechanical alloying and hot extrusion(HE).The ODS FeCrNi MEA is composed of a single face-centered cubic(FCC)matrix,in which highly dispersed oxide nanoparticles,including Y_(2)Ti_(2)O_(7),Y_(2)TiO_(5) and Y_(2)O_(3),are uniformly distributed.Compared with the FeCrNi MEA,the ODS FeCrNi MEA exhibits the improved yield strength(1120 MPa)and ultimate tensile strength(1274 MPa)with adequate ductility retention(12.1%).Theoretical analysis of the strengthening mechanism indicates that the high strength is mainly attributed to the grain-boundary strengthening caused by fine grains and the precipitation strengthening resulted from the oxide nanoparticles.Meanwhile,the matrix that easily activates mechanical twinning during the deformation process is the main reason to ensure moderate ductility.In addition,the introduction of high-density oxide nanoparticles can disperse the defect distri-bution and suppress the defect growth and irradiation-induced segregation,leading to the excellent irra-diation resistance.These findings provide innovative guidance for the development of high-performance structural materials for future nuclear energy applications with balanced strength and ductility.展开更多
Deformation behavior of a FeCrNi medium entropy alloy(MEA)prepared by powder metallurgy(P/M)method was investigated over a wide range of strain rates.The FeCrNi MEA exhibits high strain-hardening ability,which can be ...Deformation behavior of a FeCrNi medium entropy alloy(MEA)prepared by powder metallurgy(P/M)method was investigated over a wide range of strain rates.The FeCrNi MEA exhibits high strain-hardening ability,which can be attributed to the multiple deformation mechanisms,including dislocation slip,deformation induced stacking fault and mechanical twinning.The shear localization behavior of the FeCrNi MEA was also analyzed by dynamically loading hat-shaped specimens,and the distinct adiabatic shear band cannot be observed until the shear strain reaches~14.5.The microstructures within and outside the shear band exhibit different characteristics:the grains near the shear band are severely elongated and significantly refined by dislocation slip and twinning;inside the shear band,the initial coarse grains completely disappear,and transform into recrystallized ultrafine equiaxed grains by the classical rotational dynamic recrystallization mechanism.Moreover,microvoids preferentially nucleate in the central areas of the shear band where the temperature is very high and the shear stress is highly concentrated.These microvoids will coalesce into microcracks with the increase of strain,which eventually leads to the fracture of the shear band.展开更多
Reciprocity is considered one of the vital mechanisms that sustain the evolution of cooperative behavior.However,free-riding,where assistance is received but not reciprocated,poses a serious threat to reciprocity beha...Reciprocity is considered one of the vital mechanisms that sustain the evolution of cooperative behavior.However,free-riding,where assistance is received but not reciprocated,poses a serious threat to reciprocity behavior,which relies on future payback.Previous theories proposed that third-party punishment plays a vital role in preventing free-riding behavior.However,this external mechanism has inherent limitations,particularly in situations where third parties are absent.Empathy,the ability to perceive and share the emotional states of others,has long been considered a driving force behind prosocial behavior,yet its role in cooperative behavior remains underexplored.In this study,we have designed a new reciprocity paradigm,and demonstrate that rats'reciprocity behavior can stably establish even in the absence of the external mechanisms.Additionally,reciprocity experiences can enhance the empathy of wild type rats,but not oxytocin-deficient rats,towards their partners.Furthermore,oxytocindeficient rats exhibit more free-riding behaviors.Through fiber photometry recording of oxytocin probe,we found that oxytocin is remarkably released in the orbitofrontal cortex during the reciprocity task,significantly exceeding levels observed in both mutualism and individual tasks.Based on our results,we suggest that oxytocin-mediated empathy enhancement reduces rats'free-riding behavior towards their partners,thereby making reciprocity behavior more stable.This empathy-mediated internal driving force complements the previously proposed external mechanisms,providing new theories and perspectives for understanding the evolution of cooperative behavior.展开更多
基金supported by the National Natural Science Found for Distinguished Young Scholars(52225101)the Fundamental Research Funds for the Central Universities(WUT:104972024RSCbs0018 and 2023CDJYXTD-002)+1 种基金the Natural Science Foundation of Chongqing(CSTB2023NSCQ-MSX0527)the Chongqing Academician Special Fund(2022YSZXJCX0014CSTB).
文摘As one of the lightest engineering materials,magnesium(Mg)alloy possesses excellent mechanical performance,meeting the needs of versatile engineering fields and holding the potential to address cutting-edge issues in aerospace,electronics,biomedicine.The design of superhydrophobic(SHB)surfaces with micro and nanostructures can endow Mg alloys with multiple functionalities,such as self-cleaning,self-healing,antibacterial,and corrosion resistance.Over the past decade,researchers have drawn inspiration from nature to implement biomimetic design principles,resulting in the rapid development of micro/nanostructured SHB surfaces on Mg alloys,which hold great promise for biomedical applications.This review comprehensively introduces the biomimetic design principles of micro/nanostructured SHB surfaces on Mg alloys,discusses the challenges along with advantages and disadvantages of current preparation methods,and explores the future perspectives for preparing these SHB surfaces,providing strategies to enhance their performance in biomedical applications.
基金the National Natural Science Foundation of China(Grant No.52020105013 and 52401223)Natural Science Foundation of Hunan Province(Grant No.2022JJ20001)+1 种基金Science and Technology Foundation Strengthening Program(Grant No.6142902210104)T.Y.is grateful for the financial support from the Research Grants Council of the Hong Kong Special Administrative Region,China(Grant No.C1020-21G).
文摘Critical engineering applications,such as landing gears and armor protection,require structural materials withstanding high strength and significant plastic deformation.Nanoprecipitate-strengthened high-entropy alloys(HEAs)are considered as promising candidates for structural applications due to their enhanced strength and exceptional work-hardening capability.Herein,we report a FeCoNiAlTi-type HEA that achieves ultrahigh gigapascal yield strength from quasi-static to dynamic loading conditions and superb resistance to adiabatic shear failure.This is accomplished by introducing high-density coherent L1_(2) nanoprecipitates.Multiscale characterization and molecular dynamics simulation demonstrate that the L1_(2) nanoprecipitates exhibit multiple functions during impact,not only as the dislocation barrier and the dislocation transmission medium,but also as energyabsorbing islands that disperse the stress spikes through order-to-disorder transition,which result in extraordinary impact resistance.These findings shed light on the development of novel impact-resistant metallic materials.
基金supported by the National Natural Science Foundation of China(Nos.52020105013 and 51771232)the National Key Research and Development Plan of China(No.2016YFB0700302)
文摘Selective laser melting(SLM)has the advantage in preparing supersaturated solid solutions due to its unique thermal field and high solidification rate.In this study,a face-centered cubic single-phase FeCrNi medium entropy alloy(MEA)with an ultrahigh Cr content(~35 at.%)was additively manufactured by SLM.The as-built MEA shows a hierarchical microstructure of coarse columnar grains and submicron dislocation cell structures,where the cell boundaries are probed segregated with Cr and C and decorated with nano carbides.The appearance of these dislocation barriers results in an excellent combination of strength(σ_(0.2)=745 MPa,σ_(UTS)=1007 MPa)and ductility(ε_(f)=31%).The current MEA also shows a superb corrosion resistance with a corrosion current density of 0.06μA cm^(−2) in 3.5 wt.%NaCl solution,which is far lower than that of 316 L.The high content of solutioned Cr in the MEA ensures sufficient Cr supply to form an integrated Cr_(2)O_(3) passive film,and the large number of cell boundaries acting as the diffusion channels lead to the fast formation of a stable passive film over the alloy surface.
基金financially supported by the National Natural Science Funds for Distinguished Young Scholar of China (No. 51625404)the National Natural Science Foundation of China (No. 51671217)。
文摘The mechanical properties of refractory high entropy alloys(RHEAs) strongly depend on their phase structures. In this work, the phase stability of a BCC TiNbTa0.5ZrAl0.5 refractory high entropy alloy subjected to thermomechanical processing was evaluated, and the effects of phase decomposition on room/high temperature mechanical properties were quantitatively studied. It was found that, the thermomechanical processing at 800℃and 1200℃ leads to phase decomposition in the TiNbTa0.5ZrAl0.5 alloy. The phase decomposition is caused by the rapid rising of free energy of the primary BCC phase. The effect of the precipitates on room temperature strength is determined by the competition between the increasing in precipitation strengthening and the decreasing in solid solution strengthening. But at high temperatures(800-1200℃), the phase decomposition causes significant reduction in strength, mainly due to the grain boundary sliding and the decreasing in solid solution strengthening.
基金This work was supported by the National Natural Science Foun-dation of China(Nos.52020105013 and 52104365)the US National Science Foundation(Nos.DMR 1611180 and 1809640)with program directors,Drs.J.Yang,G.Shiflet,and D.Farkas.
文摘A novel cobalt-free oxide dispersion strengthened(ODS)equiatomic FeCrNi medium entropy alloy(MEA)was successfully fabricated through mechanical alloying and hot extrusion(HE).The ODS FeCrNi MEA is composed of a single face-centered cubic(FCC)matrix,in which highly dispersed oxide nanoparticles,including Y_(2)Ti_(2)O_(7),Y_(2)TiO_(5) and Y_(2)O_(3),are uniformly distributed.Compared with the FeCrNi MEA,the ODS FeCrNi MEA exhibits the improved yield strength(1120 MPa)and ultimate tensile strength(1274 MPa)with adequate ductility retention(12.1%).Theoretical analysis of the strengthening mechanism indicates that the high strength is mainly attributed to the grain-boundary strengthening caused by fine grains and the precipitation strengthening resulted from the oxide nanoparticles.Meanwhile,the matrix that easily activates mechanical twinning during the deformation process is the main reason to ensure moderate ductility.In addition,the introduction of high-density oxide nanoparticles can disperse the defect distri-bution and suppress the defect growth and irradiation-induced segregation,leading to the excellent irra-diation resistance.These findings provide innovative guidance for the development of high-performance structural materials for future nuclear energy applications with balanced strength and ductility.
基金supported by the National Natural Science Foundation of China[Grant numbers 52020105013,51771232]。
文摘Deformation behavior of a FeCrNi medium entropy alloy(MEA)prepared by powder metallurgy(P/M)method was investigated over a wide range of strain rates.The FeCrNi MEA exhibits high strain-hardening ability,which can be attributed to the multiple deformation mechanisms,including dislocation slip,deformation induced stacking fault and mechanical twinning.The shear localization behavior of the FeCrNi MEA was also analyzed by dynamically loading hat-shaped specimens,and the distinct adiabatic shear band cannot be observed until the shear strain reaches~14.5.The microstructures within and outside the shear band exhibit different characteristics:the grains near the shear band are severely elongated and significantly refined by dislocation slip and twinning;inside the shear band,the initial coarse grains completely disappear,and transform into recrystallized ultrafine equiaxed grains by the classical rotational dynamic recrystallization mechanism.Moreover,microvoids preferentially nucleate in the central areas of the shear band where the temperature is very high and the shear stress is highly concentrated.These microvoids will coalesce into microcracks with the increase of strain,which eventually leads to the fracture of the shear band.
基金supported by the STI2030-Major Projects(2022ZD0205100)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB32010300)the Shanghai Municipal Science and Technology Major Project(2018SHzDZX05).
文摘Reciprocity is considered one of the vital mechanisms that sustain the evolution of cooperative behavior.However,free-riding,where assistance is received but not reciprocated,poses a serious threat to reciprocity behavior,which relies on future payback.Previous theories proposed that third-party punishment plays a vital role in preventing free-riding behavior.However,this external mechanism has inherent limitations,particularly in situations where third parties are absent.Empathy,the ability to perceive and share the emotional states of others,has long been considered a driving force behind prosocial behavior,yet its role in cooperative behavior remains underexplored.In this study,we have designed a new reciprocity paradigm,and demonstrate that rats'reciprocity behavior can stably establish even in the absence of the external mechanisms.Additionally,reciprocity experiences can enhance the empathy of wild type rats,but not oxytocin-deficient rats,towards their partners.Furthermore,oxytocindeficient rats exhibit more free-riding behaviors.Through fiber photometry recording of oxytocin probe,we found that oxytocin is remarkably released in the orbitofrontal cortex during the reciprocity task,significantly exceeding levels observed in both mutualism and individual tasks.Based on our results,we suggest that oxytocin-mediated empathy enhancement reduces rats'free-riding behavior towards their partners,thereby making reciprocity behavior more stable.This empathy-mediated internal driving force complements the previously proposed external mechanisms,providing new theories and perspectives for understanding the evolution of cooperative behavior.
