【作者】 胡丽娟； 石进； 张鸿林； 贾璐萌； 易涛； 姚美意；

【Author】 HU Lijuan;SHI Jin;ZHANG Honglin;JIA Lumeng;YI Tao;YAO Meiyi;State key laboratory of Materials for Advanced Nuclear Energy;Institute of Materials,Shanghai University;

【机构】 上海大学核电关键材料全国重点实验室； 上海大学材料科学与工程学院材料研究所；

【摘要】 失水事故(LOCA)后锆合金原β-Zr层的力学性能对核安全至关重要。Nb作为锆合金的关键合金化元素,与O共同对原β-Zr层的力学行为产生显著影响。本文采用分子动力学(MD)方法,构建了Zr-xNb-yO(x=0,0.5%,1%,2.5%;y=0.5%,1%,质量分数,下同)合金的单晶和多晶模型,结合高温蒸汽氧化淬火后Zr-xNb合金的纳米压痕实验,系统研究了LOCA降温后O和Nb对锆合金原β-Zr层纳米压痕性能的影响。结果表明:在Zr-xNb体系中,单晶与多晶模型的纳米压痕模拟结果显示,硬度和弹性模量数值基本一致,Nb含量的变化与模型结构的变化关联影响较小;引入O后,合金的硬度和杨氏模量显著提升,其主导机制为O通过形成Cottrcll气团钉扎位错,抑制位错滑移,并导致位错密度显著增加;在Zr-xNb-yO(x=0.5%,1%,2.5%;y=0.5%,1%)体系中,1%O合金的位错密度高于0.5%O合金,位错运动受阻更为显著;而1%Nb合金因位错密度最低,对应硬度和杨氏模量最小。此外,晶界处的Nb/O比值对力学性能影响显著:当O含量相同时,Nb/O比约为0.4的合金表现出优异的塑性,但硬度和杨氏模量较低。更多还原

【Abstract】 The mechanical properties of the original β-Zr layer in zirconium alloys after a loss-ofcoolant accident(LOCA) are vital for nuclear safety.Niobium(Nb) and oxygen(O),as key alloying elements,significantly affect the mechanical behavior of this phase.In this study,molecular dynamics(MD) simulations were used to build single-crystal and polycrystalline models of Zr-xNbyO alloys(x=0,0.5 %,1 %,2.5 %;y=0.5%,1%).These models were combined with nanoindentation experiments on Zr-xNb alloys after high-temperature steam oxidation and quenching,to study how O and Nb influence the nanoindentation performance under post-LOCA cooling conditions.Results show that in the Zr-xNb system,hardness and elastic modulus remain nearly unchanged between single-crystal and polycrystalline models,indicating minimal impact from structural differences.Adding oxygen significantly increases hardness and Young’s modulus.This is mainly due to oxygen forming Cottrell atmospheres that pin dislocations,inhibit slip,and increase dislocation density.In the Zr-xNb-yO system,the 1 % O alloy has higher dislocation density than the 0.5 % O alloy,leading to stronger dislocation suppression.In contrast,the 1 % Nb alloy shows the lowest dislocation density and thus the lowest hardness and modulus.The Nb/O ratio at grain boundaries also affects mechanical properties:at the same O content,an Nb/O ratio of ～0.4 improves ductility but reduces hardness and stiffness.更多还原