Precipitate hardening is considered as an effective method to strengthen High-and medium-entropy al-loys(HEAs and MEAs),especially the recently developed Co-free HEAs/MEAs.In this work,a system-atic study on precipitation and mechanical behaviors of a Co-free HEAs with dilute amount of Al ad-dition,Ni47-xFe30Cr12Mn8AlxTi3(x=2 at.％,5 at.％and 7 at.％),is presented.Results shown that the Ni45Fe30Cr12Mn8Al2Ti3 has a face-centered cubic(FCC)+L12+η three-phased structure.With increas-ing Al content,the formation of η phase is inhibited,accompanying with an enhanced formation of B2 phase,and FCC+L12+B2 three-phased structure is thus observed in alloys with x=5 and 7.The constrained lattice mismatch between FCC matrix and L12 precipitates is decreased with increasing Al content,leading to an enhanced precipitation behavior of L12 phase.As a result of microstructural evo-lution,the mechanical properties of the aged HEAs changed:the Ni42Fe30Cr12Mn8Al5Ti3 alloy exhibits a better combination of a yield strength of 661 MPa and tensile ductility of 29.7％as compared to the 2 at.％Al alloyed HEA;and addition of Al beyond 5 at.％results in an increase of strength with a large ex-pense of ductility.We believe that the present work is helpful for developing high-performance Co-free HEAs/MEAs strengthened by nanoprecipitates via composition optimizing.

Jiantao Fan;Liming Fu;Yanle Sun;Feng Xu;Yi Ding;Mao Wen;Aidang Shan

School of Materials Science and Engineering,Shanghai Jiao Tong University,Shanghai,200240,China;Shanghai Key Laboratory of High Temperature Materials and Precision Forming,Shanghai Jiao Tong University,Shanghai,200240,China;Baowu Special Metallurgy Co.Ltd,Shanghai,200940,China

材料科学技术（英文版）

[1]Jiantao Fan;Liming Fu;Yanle Sun;Feng Xu;Yi Ding;Mao Wen;Aidang Shan-.Unveiling the precipitation behavior and mechanical properties of Co-free Ni47-xFe30Cr12Mn8AlxTi3 high-entropy alloys)[J].材料科学技术（英文版）,2022(23):25-34

Ni47,xFe30Cr12Mn8AlxTi3,Precipitate,Ni45Fe30Cr12Mn8Al2Ti3,+L12+,FCC+L12+B2,Ni42Fe30Cr12Mn8Al5Ti3,pense

Unveiling,precipitation,mechanical,properties,Co,free,high,entropy,alloys,hardening,considered,effective,method,High,medium,HEAs,MEAs,especially,recently,developed,In,this,work,system,atic,study,behaviors,dilute,amount,presented,Results,shown,that,face,centered,cubic,three,phased,structure,With,content,formation,inhibited,accompanying,enhanced,thus,observed,constrained,lattice,mismatch,between,matrix,decreased,increasing,leading,microstructural,evo,lution,aged,changed,exhibits,better,combination,yield,tensile,ductility,compared,alloyed,addition,beyond,results,increase,large,We,believe,helpful,developing,performance,strengthened,by,nanoprecipitates,via,composition,optimizing

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