B微合金化对CoNiV中熵合金微观组织和力学性能的影响及其机理  

Effect and Mechanism of B Microalloying on the Microstructure and Mechanical Properties of CoNiV Medium-Entropy Alloy

作　　者：南勇 关旭 闫海乐 唐帅[2] 贾楠 赵骧 左良 NAN Yong;GUAN Xu;YAN Haile;TANG Shuai;JIA Nan;ZHAO Xiang;ZUO Liang(Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education),School of Materials Science and Engineering,Northeastern University,Shenyang 110819,China;State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China)

机构地区：[1]东北大学材料科学与工程学院、材料各向异性与织构教育部重点实验室,沈阳110819 [2]东北大学轧制技术及连轧自动化国家重点实验室,沈阳110819

出　　处：《金属学报》2024年第12期1647-1655,共9页Acta Metallurgica Sinica

基　　金：国家重点研发计划项目No.2021YFA1200203;中央高校基本科研业务费项目No.N2202015。

摘　　要：B微合金化可显著改善金属材料的力学性能,但是其对CoNiV合金的影响仍不清楚。本工作系统研究了(CoNiV)100-xBx(x=0、0.1和0.2,原子分数,%)合金静态拉伸力学性能以及形变前后晶体结构、微观组织及微观硬度特征,揭示了微量B元素掺杂对CoNiV合金微观组织和力学性能的影响规律及作用机制。结果表明,微量B元素掺杂可以同步提升CoNiV合金的强度和塑性。0.2%B掺杂可使CoNiV合金屈服强度、极限抗拉强度和断裂延伸率分别提升12%、10%和30%。微量B元素掺杂对CoNiV合金的晶体结构、晶粒尺寸与分布、晶体学取向及塑性变形机制影响较小。(CoNiV)99.8B0.2合金室温下晶体结构仍旧为fcc结构,静态拉伸过程塑性变形机制仍为位错滑移,无应力诱发马氏体相变和形变孪生现象。纳米压痕测试结果表明,微量B元素掺杂可显著提升CoNiV合金晶界/孪晶界硬度,证实了B元素在CoNiV合金中的晶界强化作用。晶界/孪晶界强度的提升,一方面可增加位错穿过阻力,另一方面能够增加其阻碍裂纹扩展的能力,这是B掺杂使CoNiV合金强度和塑性同时提升的根源。另外,固溶到基体中的B元素也对位错运动起到一定钉扎作用,有利于合金强度的提升。CoNiV is a novel medium-entropy alloy with excellent mechanical properties.Currently,alloying CoNiV with Al has been extensively employed to improve its mechanical strength.Unfortunately,the microstructure of CoNiV changes from a single phase to a dual phase due to the addition of Al,which considerably reduces its corrosion resistance.Therefore,developing new strategies to improve its mechanical properties is imperative.In this study,the microstructure and static tensile mechanical properties of(CoNiV)100-xBx alloys(x=0,0.1,and 0.2,atomic fraction,%)are systematically investigated.The results revealed that the strength and ductility of CoNiV can be significantly improved by doping a small amount of B.With the introduction of 0.2%B,the yield strength,ultimate tensile strength,and elongation of CoNiV are improved,increasing by 12%,10%,and 30%,respectively.The crystal structure,grain size,crystallographic orientation,and plastic deformation mechanism of CoNiV are not affected due to microalloying with B.At room temperature,(CoNiV)99.8B0.2 exhibits fcc structure.The plastic deformation mechanism during static tensile deformation is manifested as dislocation slip,while martensitic transformation and twin effects induced by stress are not observed.The results of the nanohardness tests indicated that doping with trace amounts of B could remarkably enhance the grain/twin boundary hardness,confirming the grain/twin boundary strengthening effect of B on CoNiV.The strengthening of grain/twin boundaries leads to increased resistance of dislocations and provides the ability to hinder crack expansion,resulting in the simultaneous enhancement of the strength and ductility of(CoNiV)99.8B0.2.Moreover,the B element dissolved into the matrix would serve as a pinning site for dislocation,thus contributing to the increased strength of CoNiV.

关 键 词：中熵合金 CoNiV B掺杂 晶界强化 力学性能 强韧化 

分 类 号：TG156.2[金属学及工艺—热处理]