摘要
FeCrAl合金优良的高温抗氧化性能使其成为反应堆燃料包壳的候选替代材料之一,然而Cr和Al的存在会对其力学性能产生负面影响,对反应堆的安全运行造成潜在风险。为了分析FeCrAl合金体系在微观尺度的变形机制,采用分子动力学方法研究了温度和应变速率2个重要影响因素下FeCrAl单晶的力学性能,对应力应变、缺陷分布、位错密度的变化及变形机制进行了讨论,分析了溶质原子对模拟结果的影响。结果表明,温度升高导致原子热运动加剧,促进了缺陷的形成和生长,降低了原子间相互作用,导致弹性模量和抗拉强度随温度的升高而降低。应变速率的升高导致弹性模量和抗拉强度降低,低应变速率的塑性变形机制主要为孪生变形,中等应变速率下为位错滑移,高应变速率下为原子排列无序化的变形机制。温度和应变速率对α-Fe和FeCrAl具有相同的作用趋势,但与α-Fe相比,FeCrAl中的Cr和Al会产生明显的晶格畸变和应力集中,促进了缺陷和位错的形成和运动,降低材料的屈服强度和抗拉强度。基于计算结果,对FeCrAl单晶体系建立了基于F-B方程的本构模型,拓展了计算结果的应用范围。
FeCrAl alloy is one of the candidate materials for reactor fuel cladding due to its excellent oxidation resistance at high temperature. However, the presence of Cr and Al has negative effects to the mechanical properties and poses a potential risk to the safy of reactor operation. In order to analyze the deformation mechanism of FeCrAl alloy system in microscale, the mechanical properties of FeCrAl single crystal under the influence of temperature and strain rate were studied by molecular dynamics method. The defects distribution, dislocation density change and deformation mechanism were discussed, and the effect of solute atoms on the result of simulation were analyzed. The results show that the increase of temperature increases the thermal motion of atoms, promotes the formation and growth of defects, reduces the interaction between atoms, and results in the decrease of elastic modulus and tensile strength. The increase of strain rate leads to the decrease of elastic modulus and tensile strength. The plastic deformation mechanism of low strain rate is mainly deformation twinning, of middle strain rate is dislocation slip, and of high strain rate is deformation with atomic arrangement disorder. The effect of temperature and strain rate on α-Fe and FeCrAl is similar, but Cr and Al in FeCrAl cause significant lattice distortion and stress concentration, promoting the formation and movement of defects and dislocations and reducing the yield strength and tensile strength. Based on the calculated results, a constitutive model for FeCrAl crystal system was established based on Field-Backofen equation, which extended the application of the simulation results.
作者
叶天舟
姚欢
巫英伟
章静
王明军
陈平
田文喜
秋穗正
苏光辉
Ye Tianzhou;Yao Huan;Wu Yingwei;Zhang Jing;Wang Mingjun;Chen Ping;Tian Wenxi;Qiu Suizheng;Su Guanghui(State Key Laboratory of Multiphase Flow in Power Engineering,Shaanxi Key Lab.of Advanced Nuclear Energy and Technology,School of Nuclear Science and Technology,Xi’an Jiaotong University,Xi’an 710049,China;State Key Laboratory for Strength and Vibration of Mechanical Structures,Shaanxi Key Laboratory of Environment and Control for Flight Vehicle,School of Aerospace Engineering,Xi’an Jiaotong University,Xi’an 710049,China;Science and Technology on Reactor System Design Technology Laboratory,Nuclear Power Institute of China,Chengdu 610213,China)
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2023年第2期777-784,共8页
Rare Metal Materials and Engineering
基金
国家重点研发计划(2019YFB1901003)
中国核工业集团有限公司领创科研项目。
