A strong and ductile NiCoCr-based medium-entropy alloy strengthened by coherent nanoparticles with superb thermal-stability  

作　　者：D.D.Zhang J.Kuang H.Xue J.Y.Zhang G.Liu J.Sun 

机构地区：[1]State Key Laboratory for Mechanical Behavior of Materials,Xi’an Jiaotong University,Xi’an 710049,China

出　　处：《Journal of Materials Science & Technology》2023年第1期201-212,共12页材料科学技术（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.92163201,U2067219,51722104,51790482,and 51761135031);the National Key Research and Devel-opment Program of China(No.2017YFA0700701);the 111 Project 2.0 of China(No.BP2018008);the Fundamental Research Funds for the Central Universities(No.xtr022019004).

摘　　要：In this work,we designed a novel NiCoCr-based medium-entropy alloy(MEA)strengthened by coher-ent L12-nanoparticles,i.e.,(NiCoCr)92 Al 6 Ta 2(at.%).The strengthening and deformation mechanisms of the material and the coarsening kinetics of the coherent precipitates were systematically investigated.The results indicated that giant precipitation hardening and its synergy with other strengthening contributors confer on the aged material a yield strength as high as 1.0 GPa.Moreover,a unique particle-features-dependent plasticity mechanism was revealed in this alloy.That is,the alloy with a lower volume frac-tion,denser distribution,and finer particles mainly deformed by dislocation planar slip,otherwise,stack-faults-mediated plasticity was favored,rationalized by the cooperative/competitive effect of stack-fault energy,spatial confinement,and applied stress.Furthermore,the coarsening behavior of precipitate fol-lowed a modified Lifshitz-Slyozov-Wagner(LSW)model,and the nanoparticles displayed remarkably su-perior thermal stability compared to most traditional superalloys and reported multicomponent alloys.The superb coarsening resistance of precipitate originated from the coupled effect of intrinsic sluggish diffusion in multi-principal alloys and the dual-roles of Ta species as a precipitate stabilizer.This work provides a new pathway to develop strong-yet-ductile multicomponent alloys as promising candidates for high-temperature applications.

关 键 词：Medium-entropy alloy Mechanical properties Precipitation hardening Deformation mechanisms Coarsening kinetics 

分 类 号：TG139[一般工业技术—材料科学与工程]