How to achieve high-entropy alloys(HEAs)with ultrahigh strength and ductility is a challenging issue.Precipitation strengthening is one of the methods to significantly enhance strength,but unfortunately,ductility will...How to achieve high-entropy alloys(HEAs)with ultrahigh strength and ductility is a challenging issue.Precipitation strengthening is one of the methods to significantly enhance strength,but unfortunately,ductility will be lost.To overcome the strength-ductility trade-off,the strategy of this study is to induce the formation of high-density nanoprecipitates through dual aging(DA),triggering multiple deformation mechanisms,to obtain HEAs with ultrahigh strength and ductility.First,the effect of precold deformation on precipitation behavior was studied using Ni_(35)(CoFe)_(55)V_(5)Nb_(5)(at.%)HEAas the object.The results reveal that the activation energy of recrystallization is 112.2 kJ/mol.As the precold-deformation amount increases from 15%to 65%,the activation energy of precipitation gradually decreases from 178.8 to 159.7 kJ/mol.The precipitation time shortens,the size of the nanoprecipitate decreases,and the density increases.Subsequently,the thermal treatment parameters were optimized,and the DA process was customized based on the effect of precold deformation on precipitation behavior.High-density L1_(2) nanoprecipitates(~3.21×10^(25) m^(-3))were induced in the 65% precold-deformed HEA,which led to the simultaneous formation of twins and stacking fault(SF)networks during deformation.The yield strength(YS),ultimate tensile strength,and ductility of the DA-HEA are~2.0 GPa,~2.2 GPa,and~12.3%,respectively.Compared with the solid solution HEA,the YS of the DA-HEA increased by 1,657 MPa,possessing an astonishing increase of~440%.The high YS stems from the precipitation strengthening contributed by the L1_(2) nanoprecipitates and the dislocation strengthening contributed by precold deformation.The synergistically enhanced ductility stems from the high strain-hardening ability under the dual support of twinning-induced plasticity and SF-induced plasticity.展开更多
基金supported by the National Key Research and Development Project(No.2023YFA1600082)the National Natural Science Foundation of China(Nos.U2141207,52001083,52171111)+3 种基金Natural Science Foundation of Heilongjiang(No.YQ2023E026)the Fundamental Research Funds for the Central Universities(No.3072022JIP1002)Key Laboratory Found of the Ministry of Industry and Information Technology(No.GXB202201)Youth Talent Project of China National Nuclear Corporation(No.CNNC2021YTEP-HEU01).
文摘How to achieve high-entropy alloys(HEAs)with ultrahigh strength and ductility is a challenging issue.Precipitation strengthening is one of the methods to significantly enhance strength,but unfortunately,ductility will be lost.To overcome the strength-ductility trade-off,the strategy of this study is to induce the formation of high-density nanoprecipitates through dual aging(DA),triggering multiple deformation mechanisms,to obtain HEAs with ultrahigh strength and ductility.First,the effect of precold deformation on precipitation behavior was studied using Ni_(35)(CoFe)_(55)V_(5)Nb_(5)(at.%)HEAas the object.The results reveal that the activation energy of recrystallization is 112.2 kJ/mol.As the precold-deformation amount increases from 15%to 65%,the activation energy of precipitation gradually decreases from 178.8 to 159.7 kJ/mol.The precipitation time shortens,the size of the nanoprecipitate decreases,and the density increases.Subsequently,the thermal treatment parameters were optimized,and the DA process was customized based on the effect of precold deformation on precipitation behavior.High-density L1_(2) nanoprecipitates(~3.21×10^(25) m^(-3))were induced in the 65% precold-deformed HEA,which led to the simultaneous formation of twins and stacking fault(SF)networks during deformation.The yield strength(YS),ultimate tensile strength,and ductility of the DA-HEA are~2.0 GPa,~2.2 GPa,and~12.3%,respectively.Compared with the solid solution HEA,the YS of the DA-HEA increased by 1,657 MPa,possessing an astonishing increase of~440%.The high YS stems from the precipitation strengthening contributed by the L1_(2) nanoprecipitates and the dislocation strengthening contributed by precold deformation.The synergistically enhanced ductility stems from the high strain-hardening ability under the dual support of twinning-induced plasticity and SF-induced plasticity.
