拉伸方向对高熵合金纳米线变形机制的影响  

Influence of Tensile Direction on Deformation Mechanisms of High-entropy Alloy Nanowires

作　　者：李帅 LI Shuai(School of Materials Science and Engineering,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学材料科学与工程学院,北京100124

出　　处：《有色金属设计》2024年第2期58-60,共3页Nonferrous Metals Design

基　　金：国家重点研发计划资助项目(2021YFA1200201);国家自然科学基金(12174014);北京高校卓越青年科学家项目(BJJWZYJH01201910005018)。

摘　　要：体心立方结构(bcc)高熵合金的低塑性是制约其应用的关键问题,所以针对其塑性变形机制的研究具有重要意义。以往的研究仅聚焦在多晶块体体系,缺乏取向对纳米尺度单晶bcc高熵合金塑性变形机制的相关研究。通过分子动力学方法模拟了HfNbTaTiZr高熵合金纳米线在[111]和[112]两个方向下拉伸产生塑性变形时的力学行为和微观机制。结果表明:不同于之前的研究塑性变形主要由螺位错活动主导理论,沿不同方向下拉伸均发生从bcc到hcp(密排六方结构)的相变;且沿[112]方向拉伸时,在hcp相中会产生fcc(面心立方结构)相及bcc原子团簇,导致纳米线加工硬化及塑性降低;沿[111]方向拉伸时,在hcp相中会产生新的bcc相,并逐渐取代hcp相,最终令该方向的纳米线体现出大塑性。上述发现,对于bcc高熵合金的强韧性设计提供了重要了实验指导及理论依据。The low plasticity of body-centered cubic(bcc)high-entropy alloys(HEAs)is a pivotal issue restricting their application,rendering research on their plastic deformation mechanisms highly significant.Previous studies have primarily focused on polycrystalline bulk systems,lacking investigations on the orientation-dependent plastic deformation mechanisms of single-crystal bcc HEAs at the nanoscale.Through molecular dynamics simulations,this study examined the mechanical behavior and micro-mechanisms of HfNbTaTiZr HEA nanowires undergoing plastic deformation under tensile loading along[111]and[112]orientations.The results show that:Contrary to prior predominant theory that plastic deformation is governed by screw dislocation activity,both orientations experience a phase transformation from bcc to hexagonal close-packed(hcp)under tensile loading.Specifically,under tensile loading along[112]orientation,fcc(face-centered cubic)phases and bcc atomic clusters emerge in the hcp phase,leading to work hardening and reduced plasticity of the nanowire;while,under tensile loading along[111]orientation,new bcc phases emerge in the hcp phase,and gradually replace the hcp phase,ultimately conferring substantial plasticity to the nanowire in this orientation.These findings provide crucial experimental guidance and theoretical foundations for designing stronger and tougher bcc HEAs.

关 键 词：bcc高熵合金 塑性变形机制 分子动力学 纳米尺度 

分 类 号：O732[理学—晶体学]