超强金属/高熵合金纳米叠层材料:利用相变的尺寸约束效应  

Ultra-strong metal/high entropy alloy nanolaminates:Utilizing size constraining effects on phase transformation

作　　者：赵宇芳 王亚强 张金钰 吴凯 刘刚 孙军 Yufang Zhao;Yaqiang Wang;Jinyu Zhang;Kai Wu;Gang Liu;Jun Sun(State Key Laboratory for Mechanical Behavior of Materials,Xi’an Jiaotong University,Xi’an 710049,China)

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

出　　处：《Science China Materials》2023年第11期4207-4219,共13页中国科学（材料科学（英文版）

基　　金：supported by the National Natural Science Foundation of China(U2067219,92163201,52001247);the Initiative Postdocs Supporting Program(BX20190266);Shaanxi Province Youth Innovation Team Project(22JP042);the Fundamental Research Funds for the Central Universities(xtr022019004,xzy022019071)。

摘　　要：本文通过磁控溅射制备了具有相同组元层厚度(h=5-150 nm)的Cu/Fe_(50)Mn_(30)Co_(10)Cr_(10)和Cu/Fe_(50)Mn_(30)Co_(10)Ni_(10)金属/高熵合金纳米多层膜,对比研究了强约束条件下非等原子比Fe_(50)Mn_(30)Co_(10)Cr_(10)和Fe50Mn30-Co10Ni10高熵合金的相稳定性及其对力学性能的影响.沉积过程中由于组元Cu层的约束与模板效应,组元Fe_(50)Mn_(30)Co_(10)Cr_(10)层在层厚小于25 nm时发生了尺寸驱动的HCP到FCC相变.与此同时,由于堆垛层错可以作为相变的形核质点,Cu/Fe_(50)Mn_(30)Co_(10)Cr_(10)多层膜在压入变形过程中也发生了应力驱动的HCP到FCC相变.相比之下,Cu/Fe_(50)Mn_(30_)-Co_(10)Ni_(10)多层膜组织稳定,没有发生尺寸/应力驱动的相变行为.随层厚减小,两种Cu/高熵合金纳米多层膜均表现出了从层厚无关转变为层厚相关的超高硬度,这源于偏位错形核主导的强化机制.尤为特别的是,Cu/Fe_(50)Mn_(30)Co_(10)Cr_(10)多层膜的归一化硬度(实测硬度与混合法则预测硬度的比值)远高于传统的Cu基双金属多层膜.本文研究结果从调控高熵合金相变行为的角度为提高复合材料的强度和塑性提供了新思路.In this work,the phase stability of non-equia-tomic Fe_(50)Mn_(30)Co_(10)Cr_(10)and Fe_(50)Mn_(30)Co_(10)Ni_(10)high entropy alloys(HEAs)under strong constraining conditions as well as its effect on the mechanical properties were comparatively studied in the magnetron sputtered Cu/Fe_(50)Mn_(30)Co_(10)Cr_(10)and Cu/Fe_(50)Mn_(30)Co_(10)Ni_(10)nanolaminates with the layer thickness h ranging from 5 to 150 nm.During the deposition process,the size-driven hexagonal close packed(HCP)to face-centered cubic(FCC)phase transformation occurs in the Fe50Mn30-Co10Cr10 layers as h<25 nm due to the nanolayer constraining and template effects.Meanwhile,the stress-driven HCP-to-FCC phase transformation also occurs in the Cu/Fe_(50)Mn_(30_)-Co_(10)Ni_(10) nanolaminates during the indentation deformation,which is attributed to the nucleation of stacking faults that could serve as the nuclei for phase transformation.However,the Fe_(50)Mn_(30)Co_(10)Ni_(10)layers maintain stable microstructure without size-driven nor stress-driven phase transformation.With reducing h,both the Cu/HEA nanolaminates exhibit a transition from h-independent to h-dependent ultrahigh hardness,as elucidated by the partial dislocation-mediated mechanisms.In particular,the normalized hardness of Cu/Fe_(50)Mn_(30)Co_(10)Cr_(10)nanolaminates represented by the ratio of measured hardness to predicted hardness from the rule-of-mixture is more superior to conventional Cu-based bimetal nanolaminates.These findings provide a new perspective to tailor the phase transformation of HEAs and thereby enhance their strength and plasticity.

关 键 词：metal/high entropy alloy nanolaminates phase transformation HARDNESS INTERFACES size effects 

分 类 号：TB383.1[一般工业技术—材料科学与工程]