Dual-phase heterogeneous structures confer eutectic high-entropy alloy(EHEA)with excellent strength-ductility synergy under quasi-static tensile loading.However,it is questionable whether the EHEAs pos-sess equally go...Dual-phase heterogeneous structures confer eutectic high-entropy alloy(EHEA)with excellent strength-ductility synergy under quasi-static tensile loading.However,it is questionable whether the EHEAs pos-sess equally good impact toughness because the phase interfaces are vulnerable to crack initiation.This work aimed to study the Charpy impact toughness and fracture behavior of AlCoCrFeNi_(2.1) EHEA.The results indicate that while maintaining high tensile strength and ductility,the AlCoCrFeNi_(2.1) EHEA also shows a satisfactory impact toughness of 25.86 J/cm^(2),superior to most other dual-phase alloys like TC4 titanium alloy or DP steel.Fractography analysis reveals characteristic regions of the fracture surface,which suggests energy absorption mechanisms primarily through ductile dimples,flat cleavage facets,secondary cracks,and microvoids,corresponding to a ductile-brittle mixed fracture mode.Detailed obser-vations of the deformed microstructure through TEM and EBSD demonstrate that FCC(L1_(2))and BCC(B2)phases underwent concurrent tearing along their phase boundaries,indicating a crucial influence of phase boundaries over crack initiation and propagation.The FCC(L1_(2))phase bore almost all plastic deformation of the sample through dislocation slip,whereas the BCC(B2)phase underwent a rapid shearing but almost no dislocation slip.Crack initiation under impact loading typically starts at the FCC(L1_(2))/BCC(B2)inter-face before propagating through the BCC(B2)phase.Additionally,this work further examines the effect of sample size and notch shape on the impact toughness of AlCoCrFeNi_(2.1) EHEA.A comparative analysis of the mechanical behavior under static and impact loading was also conducted,highlighting differences and connections in stress distribution and fracture surface morphology.The study offers valuable insights into the mechanical response and fracture behavior of AlCoCrFeNi_(2.1) EHEA under impact loading,provid-ing crucial information for its potential industrial applications.展开更多
基金financially supported by the Natural Science Spe-cial(Special Post)Research Foundation of Guizhou University(No.2023-46)the Youth Science and Technology Talent Development Program of Guizhou(No.QKJ[2024]24)the National Natural Science Foundation of China(Nos.52274260,52074096,and 52164017).
文摘Dual-phase heterogeneous structures confer eutectic high-entropy alloy(EHEA)with excellent strength-ductility synergy under quasi-static tensile loading.However,it is questionable whether the EHEAs pos-sess equally good impact toughness because the phase interfaces are vulnerable to crack initiation.This work aimed to study the Charpy impact toughness and fracture behavior of AlCoCrFeNi_(2.1) EHEA.The results indicate that while maintaining high tensile strength and ductility,the AlCoCrFeNi_(2.1) EHEA also shows a satisfactory impact toughness of 25.86 J/cm^(2),superior to most other dual-phase alloys like TC4 titanium alloy or DP steel.Fractography analysis reveals characteristic regions of the fracture surface,which suggests energy absorption mechanisms primarily through ductile dimples,flat cleavage facets,secondary cracks,and microvoids,corresponding to a ductile-brittle mixed fracture mode.Detailed obser-vations of the deformed microstructure through TEM and EBSD demonstrate that FCC(L1_(2))and BCC(B2)phases underwent concurrent tearing along their phase boundaries,indicating a crucial influence of phase boundaries over crack initiation and propagation.The FCC(L1_(2))phase bore almost all plastic deformation of the sample through dislocation slip,whereas the BCC(B2)phase underwent a rapid shearing but almost no dislocation slip.Crack initiation under impact loading typically starts at the FCC(L1_(2))/BCC(B2)inter-face before propagating through the BCC(B2)phase.Additionally,this work further examines the effect of sample size and notch shape on the impact toughness of AlCoCrFeNi_(2.1) EHEA.A comparative analysis of the mechanical behavior under static and impact loading was also conducted,highlighting differences and connections in stress distribution and fracture surface morphology.The study offers valuable insights into the mechanical response and fracture behavior of AlCoCrFeNi_(2.1) EHEA under impact loading,provid-ing crucial information for its potential industrial applications.
