A common problem for Zn alloys is the trade-off between antibacterial ability and biocompatibility.This paper proposes a strategy to solve this problem by increasing release ratio of Ca^(2+)ions,which is realized by s...A common problem for Zn alloys is the trade-off between antibacterial ability and biocompatibility.This paper proposes a strategy to solve this problem by increasing release ratio of Ca^(2+)ions,which is realized by significant refinement of CaZn13 particles through bottom circulating water-cooled casting(BCWC)and rolling.Compared with conventionally fabricated Zn-0.3Ca alloy,the BCWC-rolled alloy shows higher antibacterial abilities against E.coli and S.aureus,meanwhile much less toxicity to MC3T3-E1 cells.Additionally,plasticity,degradation uniformity,and ability to induce osteogenic differentiation in vitro of the alloy are improved.The elongation up to 49%,which is the highest among Zn alloys with Ca,and is achieved since the sizes of CaZn_(13) particles and Zn grains are small and close.As a result,the long-standing problem of low formability of Zn alloys containing Ca has also been solved due to the elimination of large CaZn_(13) particles.The BCWC-rolled alloy is a promising candidate of making GBR membrane.展开更多
The coarsening behavior and strengthening effect of L1_(2)-Ni_(3)(Ti,Al)precipitates in a face-centered-cubic(FCC)(FeCoNi)_(92)Al_(2.5)Ti_(5.5) high entropy alloy have been systematically investigated.The coherent L1_...The coarsening behavior and strengthening effect of L1_(2)-Ni_(3)(Ti,Al)precipitates in a face-centered-cubic(FCC)(FeCoNi)_(92)Al_(2.5)Ti_(5.5) high entropy alloy have been systematically investigated.The coherent L1_(2) precipitates,uniformly distributed throughout the FCC matrix,consistently retain a spherical shape.The coarsening rate coefficient of precipitate is determined by employing the Philippe-Voorhees(PV)model,suggesting excellent thermal stability.Furthermore,the elemental partitioning and compositional evolution of the L1_(2) precipitates is analyzed by atom probe tomography,which identify aluminum(Al)as the slowest diffusion species during the coarsening process.In addition,the precipitation strengthening effect is quantified to ascertain the optimal size of the precipitates.Our study enhances the understanding of precipitate coarsening in high entropy alloys,presenting valuable insights into their thermal stability and mechanical properties.展开更多
In this study, mechanical tests were conducted oil a face-centered cubic FeCoNiCrMn high-entropy alloy, both in tension and compression, in a wide range of strain rates （10^-4-10^4 s^-1） to systematically investigat...In this study, mechanical tests were conducted oil a face-centered cubic FeCoNiCrMn high-entropy alloy, both in tension and compression, in a wide range of strain rates （10^-4-10^4 s^-1） to systematically investigate its dynamic response and underlying deformation mechanism. Materials with different grain sizes were tested to understand the effect of grain size, thus grain boundary volume, on the mechanical prop-erties. Microstructures of various samples both before and after deformation were examined using elec-tron backscatter diffraction and transmission electron microscopy. The dislocation structure as well as deformation-induced twins were analyzed and correlated with the measured mechanical properties. Plastic stability during tension of the current high-entropy alloy （HEA）, in particular, at dynamic strain rates, was discussed in lights of strain-rate sensitivity and work hardening rate. It was found that, under dynamic conditions, the strength and uniform ductility increased simultaneously as a result of the mas-sive formation of deformation twins. Specifically, an ultimate tensile strength of 734 MPa and uniform elongation of-63% are obtained at 2.3×10^3 s^-1, indicating that the alloy has great potential for energy absorption upon impact loading.展开更多
Conventional trial-and-error method is usually time-consuming and expensive for multi-objective optimization of Mg alloys.Although machine learning exhibits great potential to accelerate related research studies,machi...Conventional trial-and-error method is usually time-consuming and expensive for multi-objective optimization of Mg alloys.Although machine learning exhibits great potential to accelerate related research studies,machine learning prediction of properties of Mg alloys is often a prediction of a single target at a time.To address this,this paper integrates non-dominated sorting genetic algorithm III multiobjective optimization algorithm with light gradient boosting machine algorithm to simultaneously optimize yield strength,ultimate tensile strength,and elongation of Mg alloys.This is the first time that simultaneous machine learning optimization of these three objectives has been achieved for Mg alloys.展开更多
Oxidation resistance enhancement of pure Ti often comes at the cost of reduced ductility,which is frequently the problem through alloying with sole Al,Si,W,Mo and B.To overcome the short coming of single element alloy...Oxidation resistance enhancement of pure Ti often comes at the cost of reduced ductility,which is frequently the problem through alloying with sole Al,Si,W,Mo and B.To overcome the short coming of single element alloying,this paper proposes a multi-element low-alloying strategy to take advantage of synergistic effects and resolve the conflict between oxidation resistance and ductility.It demonstrates that the addition of a small quantity of Ta(0.51wt%)can boost both oxidation resistance and ductility in comparison to pure Ti.Furthermore,the combined addition of a small amount(0.54 wt%)of Ta,Nb and Si not only preserves good ductility of pure Ti,but also reduces mass gains to 14%-67%of pure Ti during 100 h oxidation at 650-850℃in air.This indicates even better oxidation resistance than that obtained through the use of Ta,Nb,or Nb+Ta additions.The Ta+Nb+Si alloying creates an oxide layer that is less porous and more resistant to stratification and spalling.Consequently,a 3-μm N-rich layer can form in the Ti substrate beneath the oxide scale,in which phase transformation generates coherent Ti_(2)N with(0001)_(Ti)as the habit plane,with N atoms prefers to diffuse along■than along[0001]_(Ti).The completely transformed Ti_(2)N region or partially transformed Ti+Ti_(2)N region can effectively impede oxygen invasion.Therefore,the multielement low-alloying strategy is promising for enhancing both oxidation resistance and mechanical properties of metallic materials in the future.展开更多
1.Introduction Damping alloys are considered to be the most direct and effective approach to reducing unwanted vibration and noise in industrial applications.In particular,it is urgent to develop damping alloys that h...1.Introduction Damping alloys are considered to be the most direct and effective approach to reducing unwanted vibration and noise in industrial applications.In particular,it is urgent to develop damping alloys that have highdamping capacity(tanδ)as well as high strength,and a large operating temperature range to meet the demands of extreme working conditions,such as outer space.However,the application temperature of existing damping alloys is limited,which is one of the biggest challenges for developing highperformance damping alloys.For Fe-Mn binary alloys.展开更多
Although a few high-strength biodegradable Zn alloys with yield strengths(YSs)over 300 MPa in rolled state have been developed,their elongations(ELs)are generally less than 30%.This study developed rolled Zn-2Cu-x Li(...Although a few high-strength biodegradable Zn alloys with yield strengths(YSs)over 300 MPa in rolled state have been developed,their elongations(ELs)are generally less than 30%.This study developed rolled Zn-2Cu-x Li(x=0.2 wt.%,0.5 wt.%,0.8 wt.%)alloys with YSs of 316-335 MPa and ELs of 44%-61%.Three-dimensional atom probe(3DAP)and time of flight secondary ion mass spectrometry(TOF-SIMS)were employed to characterize Li distribution.Three kinds of Zn-Cu-Li ternary phases are identified,which are blockyε′-(Cu_(0.5),Li_(0.5))Zn 4,blockyβ′-(Li_(0.9),Cu_(0.1))Zn 4,and small roundγparticles with high Li content in the annealed state.Other identified phases are Zn,β-LiZn 4,andε-CuZn 4 phases.With the increase of Li content in the alloys,ε′phase with 6.50 at.%Cu transforms intoβ′phase with 2.12 at.%Cu,i.e.,the average level in the alloys.Withinε′phase,there exist nano-scale Li clusters andεphase,resulting inε′/εstructure.Dense Zn laths precipitate fromβ′phase,resulting inβ′/Zn lamellar structure.The lamel-lar structure is the matrix of Zn-2Cu-0.8Li and leads to near-isotropic plasticity.Electrochemistry tests show that degradation rates fall in the range of 153-196μm/year,which decrease with Li content.All the alloys exert positive effects on the growth of MC3T3-E1 cells with 10%extract.This research reveals how microstructure evolves in Zn-2Cu-x Li alloys,which lays the foundation for their future applications.展开更多
基金financially supported by Xiongan New Area Science and Technology Innovation Project(2022XACX0600)the National Natural Science Foundation of China(No.52231010 and No.52071028)Beijing Nova Program(2022 Beijing Nova Program Cross Cooperation Program No.20220484178).
文摘A common problem for Zn alloys is the trade-off between antibacterial ability and biocompatibility.This paper proposes a strategy to solve this problem by increasing release ratio of Ca^(2+)ions,which is realized by significant refinement of CaZn13 particles through bottom circulating water-cooled casting(BCWC)and rolling.Compared with conventionally fabricated Zn-0.3Ca alloy,the BCWC-rolled alloy shows higher antibacterial abilities against E.coli and S.aureus,meanwhile much less toxicity to MC3T3-E1 cells.Additionally,plasticity,degradation uniformity,and ability to induce osteogenic differentiation in vitro of the alloy are improved.The elongation up to 49%,which is the highest among Zn alloys with Ca,and is achieved since the sizes of CaZn_(13) particles and Zn grains are small and close.As a result,the long-standing problem of low formability of Zn alloys containing Ca has also been solved due to the elimination of large CaZn_(13) particles.The BCWC-rolled alloy is a promising candidate of making GBR membrane.
基金supported by the National Key Research and Development Program of China(No.2022YFE0134400)the State Key Laboratory for Advanced Metals and Materials(No.2023-Z05)+1 种基金the National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact(No.6142902220101)the Hunan Provincial Postgraduate Scientific Research Innovation Project(No.CX20230181).
文摘The coarsening behavior and strengthening effect of L1_(2)-Ni_(3)(Ti,Al)precipitates in a face-centered-cubic(FCC)(FeCoNi)_(92)Al_(2.5)Ti_(5.5) high entropy alloy have been systematically investigated.The coherent L1_(2) precipitates,uniformly distributed throughout the FCC matrix,consistently retain a spherical shape.The coarsening rate coefficient of precipitate is determined by employing the Philippe-Voorhees(PV)model,suggesting excellent thermal stability.Furthermore,the elemental partitioning and compositional evolution of the L1_(2) precipitates is analyzed by atom probe tomography,which identify aluminum(Al)as the slowest diffusion species during the coarsening process.In addition,the precipitation strengthening effect is quantified to ascertain the optimal size of the precipitates.Our study enhances the understanding of precipitate coarsening in high entropy alloys,presenting valuable insights into their thermal stability and mechanical properties.
基金supported by the National Natural Science Foundation of China(51671018,51531001,51422101,51371003,and 51671021)111 Project(B07003)+5 种基金International S&T Cooperation Program of China(2015DFG52600)Program for Changjiang Scholars and Innovative Research Team in University of China(IRT_14R05)the Projects of SKL-AMM-USTB(2016Z-04,2016-09,2016Z-16)the financial support from the Top-Notch Young Talents Programthe Fundamental Research Funds for the Central Universitiesthe financial support by US-NSF under contract DMR-1408722
文摘In this study, mechanical tests were conducted oil a face-centered cubic FeCoNiCrMn high-entropy alloy, both in tension and compression, in a wide range of strain rates （10^-4-10^4 s^-1） to systematically investigate its dynamic response and underlying deformation mechanism. Materials with different grain sizes were tested to understand the effect of grain size, thus grain boundary volume, on the mechanical prop-erties. Microstructures of various samples both before and after deformation were examined using elec-tron backscatter diffraction and transmission electron microscopy. The dislocation structure as well as deformation-induced twins were analyzed and correlated with the measured mechanical properties. Plastic stability during tension of the current high-entropy alloy （HEA）, in particular, at dynamic strain rates, was discussed in lights of strain-rate sensitivity and work hardening rate. It was found that, under dynamic conditions, the strength and uniform ductility increased simultaneously as a result of the mas-sive formation of deformation twins. Specifically, an ultimate tensile strength of 734 MPa and uniform elongation of-63% are obtained at 2.3×10^3 s^-1, indicating that the alloy has great potential for energy absorption upon impact loading.
基金supported by the National Key R&D Program of China(No.2021YFB3701100)National Natural Science Foundation of China(No.52271088)Beijing Nova Program(2022 Beijing Nova Program Cross Cooperation Program No.20220484178).
文摘Conventional trial-and-error method is usually time-consuming and expensive for multi-objective optimization of Mg alloys.Although machine learning exhibits great potential to accelerate related research studies,machine learning prediction of properties of Mg alloys is often a prediction of a single target at a time.To address this,this paper integrates non-dominated sorting genetic algorithm III multiobjective optimization algorithm with light gradient boosting machine algorithm to simultaneously optimize yield strength,ultimate tensile strength,and elongation of Mg alloys.This is the first time that simultaneous machine learning optimization of these three objectives has been achieved for Mg alloys.
基金financially supported by the National Natural Science Foundation of China(No.52271088)Beijing Nova Program(2022 Beijing Nova Program Cross Cooperation Program No.20220484178)the National Key R&D Program of China(No.2016YFB0301200)。
文摘Oxidation resistance enhancement of pure Ti often comes at the cost of reduced ductility,which is frequently the problem through alloying with sole Al,Si,W,Mo and B.To overcome the short coming of single element alloying,this paper proposes a multi-element low-alloying strategy to take advantage of synergistic effects and resolve the conflict between oxidation resistance and ductility.It demonstrates that the addition of a small quantity of Ta(0.51wt%)can boost both oxidation resistance and ductility in comparison to pure Ti.Furthermore,the combined addition of a small amount(0.54 wt%)of Ta,Nb and Si not only preserves good ductility of pure Ti,but also reduces mass gains to 14%-67%of pure Ti during 100 h oxidation at 650-850℃in air.This indicates even better oxidation resistance than that obtained through the use of Ta,Nb,or Nb+Ta additions.The Ta+Nb+Si alloying creates an oxide layer that is less porous and more resistant to stratification and spalling.Consequently,a 3-μm N-rich layer can form in the Ti substrate beneath the oxide scale,in which phase transformation generates coherent Ti_(2)N with(0001)_(Ti)as the habit plane,with N atoms prefers to diffuse along■than along[0001]_(Ti).The completely transformed Ti_(2)N region or partially transformed Ti+Ti_(2)N region can effectively impede oxygen invasion.Therefore,the multielement low-alloying strategy is promising for enhancing both oxidation resistance and mechanical properties of metallic materials in the future.
基金supported by the National Natural Science Foundation of China(Nos.52071024,52225103,51971017,52271003,and 52101188)the Funds for Creative Research Groups of NSFC(No.51921001)+6 种基金Projects of International Cooperation and Exchanges of NSFC(Nos.51961160729 and 52061135207)National Key Research and Development Program of China(Nos.2022YFB3705201 and 2022YFB4602101)111 Project(No.BP0719004)Program for Changjiang Scholars and Innovative Research Team in University of China(IRT_14R05)the Fundamental Research Funds for the Central Universities of China:FRF-TP-22-005C2,FRF-TP-22-001C2Project funded by China Postdoctoral Science Foundation(2020M680009)by Key Laboratory of Construction Hydraulic Robots of Anhui Higher Education Institutes,Tongling University(Grant No.TLXYCHR-O-21YB02).
文摘1.Introduction Damping alloys are considered to be the most direct and effective approach to reducing unwanted vibration and noise in industrial applications.In particular,it is urgent to develop damping alloys that have highdamping capacity(tanδ)as well as high strength,and a large operating temperature range to meet the demands of extreme working conditions,such as outer space.However,the application temperature of existing damping alloys is limited,which is one of the biggest challenges for developing highperformance damping alloys.For Fe-Mn binary alloys.
基金financially supported by Xiongan New Area Science and Technology Innovation Project(2022XACX0600)the National Natural Science Foundation of China(Nos.52231010,52071028).
文摘Although a few high-strength biodegradable Zn alloys with yield strengths(YSs)over 300 MPa in rolled state have been developed,their elongations(ELs)are generally less than 30%.This study developed rolled Zn-2Cu-x Li(x=0.2 wt.%,0.5 wt.%,0.8 wt.%)alloys with YSs of 316-335 MPa and ELs of 44%-61%.Three-dimensional atom probe(3DAP)and time of flight secondary ion mass spectrometry(TOF-SIMS)were employed to characterize Li distribution.Three kinds of Zn-Cu-Li ternary phases are identified,which are blockyε′-(Cu_(0.5),Li_(0.5))Zn 4,blockyβ′-(Li_(0.9),Cu_(0.1))Zn 4,and small roundγparticles with high Li content in the annealed state.Other identified phases are Zn,β-LiZn 4,andε-CuZn 4 phases.With the increase of Li content in the alloys,ε′phase with 6.50 at.%Cu transforms intoβ′phase with 2.12 at.%Cu,i.e.,the average level in the alloys.Withinε′phase,there exist nano-scale Li clusters andεphase,resulting inε′/εstructure.Dense Zn laths precipitate fromβ′phase,resulting inβ′/Zn lamellar structure.The lamel-lar structure is the matrix of Zn-2Cu-0.8Li and leads to near-isotropic plasticity.Electrochemistry tests show that degradation rates fall in the range of 153-196μm/year,which decrease with Li content.All the alloys exert positive effects on the growth of MC3T3-E1 cells with 10%extract.This research reveals how microstructure evolves in Zn-2Cu-x Li alloys,which lays the foundation for their future applications.
