Developing high-performance alloys with gigapascal strength and excellent ductility is crucial for modern engineering applications.The concept of multi-component high/medium entropy alloys(H/MEAs)provides an innovativ...Developing high-performance alloys with gigapascal strength and excellent ductility is crucial for modern engineering applications.The concept of multi-component high/medium entropy alloys(H/MEAs)provides an innovative approach to designing such alloys.In this work,we developed the Co_(1.5)CrNi_(1.5)Al_(0.2)Ti_(0.2)MEA,which exhibits outstanding mechanical properties at room temperature through low-temperature pre-aging followed by annealing treatment.Tensile testing reveals that the MEA possesses an ultrahigh yield strength of 20±0785 MPa,an ultimate tensile strength of 2365±70 MPa,and exceptional ductility of 15.8%±1.7%.The superior tensile properties are attributed to the formation of fully recrystal-lized heterogeneous structures(HGS)composed of ultrafine grain(UFG)and fine grain(FG)regions,along with discontinuous precipitation of coherent nano-size lamellar L1_(2)precipitates.The mechanical incompatibility between the UFG region and the FG regions during deformation induces the accumulation of a large number of geometrically necessary dislocations at the interface,resulting in strain distribution and hetero-deformation-induced(HDI)stress accumulation,contributing significantly to HDI strengthening.HDI strengthening,precipitation strengthening,and grain boundary strengthening are the primary mechanisms responsible for the ultra-high yield strength of the MEA.During deformation,the dominant deformation mechanisms include dislocation slip,deformation-induced stacking faults,and Lomer-Cottrell locks,with minor deformation twinning.The synergistic interaction of these multiple deformation modes provides the MEA with excellent work hardening capability,delaying plastic instability and achieving an excellent combination of strength and ductility.This study provides an effective strategy for synergistically strengthening MEAs by combining HDI strengthening with traditional strengthening mechanisms.These findings pave the way for the development of advanced structural materials with high performance tailored for demanding applications in engineering.展开更多
Nanostructured silver was obtained by potentiostatic electrolysis.The effects of ionized surfactant(sodium dodecanesulphonate)and the substrate(Cu and Ti)on the morphology of depositions were investigated.It is found ...Nanostructured silver was obtained by potentiostatic electrolysis.The effects of ionized surfactant(sodium dodecanesulphonate)and the substrate(Cu and Ti)on the morphology of depositions were investigated.It is found that morphologies of silver nanostructures can be simply controlled via change of the substrate.Spherical Ag nanoparticles with narrow size distribution were obtained by electrodeposition in Ag NO3-SDS aqueous solution on copper substrate.In the case of titanium substrate,silver dendrite structures were obtained.Despite of different morphologies,XRD and TEM results showed that the as-prepared samples belong to face-centered cubic silver structure with good crystallinity.The formation mechanism of different silver nanostructures was discussed.展开更多
In this study,a high entropy alloy(HEA)with remarkable mechanical performance and corrosion resistance was fabricated through L1_(2) precipitation strengthening.The tensile test at room temperature revealed that the C...In this study,a high entropy alloy(HEA)with remarkable mechanical performance and corrosion resistance was fabricated through L1_(2) precipitation strengthening.The tensile test at room temperature revealed that the CoCrFeNi_(2)Al_(0.2)Ti_(0.2)HEA,with the highest L1_(2) precipitate content,exhibited the most outstanding combination of mechanical properties characterized by a yield strength of 1656±62 MPa,a tensile strength of 1876±94 MPa,and excellent ductility of 21%±1.0%.The remarkable strength was primarily attributed to the synergistic strengthening effects of precipitation strengthening and grain boundary strengthening,whereas the excellent ductility correlates with the combined mechanisms of dislocation slip,deformation-induced stacking faults,and the Lomer-Cottrell locks.Electrochemical tests demonstrated a significant improvement in corrosion resistance with the introduction of L1_(2) precipitates.X-ray photoelectron spectroscopy analysis further revealed that the increased corrosion resistance resulted from a higher concentration of corrosion-resistant components in the passivation film,facilitated by the presence of L1_(2) precipitates.First-principles calculations revealed that the enhanced corrosion resistance is due to the higher work function and lower adsorption energy of the L1_(2) precipitates compared to the matrix phase contributes to the superior performance.This research provides valuable insights into the fabrication of high-performance alloys and offers theoretical guidance for developing next-generation materials with optimized properties.展开更多
基金supported by the National Key Research and Development Program of China(No.2022YFA1603800)the National Natural Science Foundation of China(No.12274362).
文摘Developing high-performance alloys with gigapascal strength and excellent ductility is crucial for modern engineering applications.The concept of multi-component high/medium entropy alloys(H/MEAs)provides an innovative approach to designing such alloys.In this work,we developed the Co_(1.5)CrNi_(1.5)Al_(0.2)Ti_(0.2)MEA,which exhibits outstanding mechanical properties at room temperature through low-temperature pre-aging followed by annealing treatment.Tensile testing reveals that the MEA possesses an ultrahigh yield strength of 20±0785 MPa,an ultimate tensile strength of 2365±70 MPa,and exceptional ductility of 15.8%±1.7%.The superior tensile properties are attributed to the formation of fully recrystal-lized heterogeneous structures(HGS)composed of ultrafine grain(UFG)and fine grain(FG)regions,along with discontinuous precipitation of coherent nano-size lamellar L1_(2)precipitates.The mechanical incompatibility between the UFG region and the FG regions during deformation induces the accumulation of a large number of geometrically necessary dislocations at the interface,resulting in strain distribution and hetero-deformation-induced(HDI)stress accumulation,contributing significantly to HDI strengthening.HDI strengthening,precipitation strengthening,and grain boundary strengthening are the primary mechanisms responsible for the ultra-high yield strength of the MEA.During deformation,the dominant deformation mechanisms include dislocation slip,deformation-induced stacking faults,and Lomer-Cottrell locks,with minor deformation twinning.The synergistic interaction of these multiple deformation modes provides the MEA with excellent work hardening capability,delaying plastic instability and achieving an excellent combination of strength and ductility.This study provides an effective strategy for synergistically strengthening MEAs by combining HDI strengthening with traditional strengthening mechanisms.These findings pave the way for the development of advanced structural materials with high performance tailored for demanding applications in engineering.
基金supported by the National Foundations of China-Australia Special Fund for Scientific and Technological Cooperation(grant No.20711120186)the Natural Science Foundations of China(grant No.20873184)+2 种基金the Natural Science Foundations of Guangdong Province(grant No.8151027501000095)the Science and Technology plan Projects of Guangdong Province(grant No.2008B010600040)the Instrumental Technique Research Foundation of Instrumental Analysis and Research Center,Sun Yat-sen University(grant No.2009006)
文摘Nanostructured silver was obtained by potentiostatic electrolysis.The effects of ionized surfactant(sodium dodecanesulphonate)and the substrate(Cu and Ti)on the morphology of depositions were investigated.It is found that morphologies of silver nanostructures can be simply controlled via change of the substrate.Spherical Ag nanoparticles with narrow size distribution were obtained by electrodeposition in Ag NO3-SDS aqueous solution on copper substrate.In the case of titanium substrate,silver dendrite structures were obtained.Despite of different morphologies,XRD and TEM results showed that the as-prepared samples belong to face-centered cubic silver structure with good crystallinity.The formation mechanism of different silver nanostructures was discussed.
基金financially supported by the National Key Research and Development Program of China(No.2022YFA1603800)the National Natural Science Foundation of China(No.12274362)the open research fund of Songshan Lake Materials Laboratory(2022SLABFK01).
文摘In this study,a high entropy alloy(HEA)with remarkable mechanical performance and corrosion resistance was fabricated through L1_(2) precipitation strengthening.The tensile test at room temperature revealed that the CoCrFeNi_(2)Al_(0.2)Ti_(0.2)HEA,with the highest L1_(2) precipitate content,exhibited the most outstanding combination of mechanical properties characterized by a yield strength of 1656±62 MPa,a tensile strength of 1876±94 MPa,and excellent ductility of 21%±1.0%.The remarkable strength was primarily attributed to the synergistic strengthening effects of precipitation strengthening and grain boundary strengthening,whereas the excellent ductility correlates with the combined mechanisms of dislocation slip,deformation-induced stacking faults,and the Lomer-Cottrell locks.Electrochemical tests demonstrated a significant improvement in corrosion resistance with the introduction of L1_(2) precipitates.X-ray photoelectron spectroscopy analysis further revealed that the increased corrosion resistance resulted from a higher concentration of corrosion-resistant components in the passivation film,facilitated by the presence of L1_(2) precipitates.First-principles calculations revealed that the enhanced corrosion resistance is due to the higher work function and lower adsorption energy of the L1_(2) precipitates compared to the matrix phase contributes to the superior performance.This research provides valuable insights into the fabrication of high-performance alloys and offers theoretical guidance for developing next-generation materials with optimized properties.
