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金属学报  2024, Vol. 60 Issue (8): 1109-1118    DOI: 10.11900/0412.1961.2024.00062
  研究论文 本期目录 | 过刊浏览 |
利用小角中子核磁散射分离研究AerMet100钢中纳米析出相的形貌和成分
柯于斌1,2(), 李彬3, 段辉平3()
1 散裂中子源科学中心 东莞 523803
2 中国科学院高能物理研究所 北京 100049
3 北京航空航天大学 材料科学与工程学院 北京 100191
Morphology and Chemical Composition of Nanoprecipitate in AerMet100 Steel by Separation of the Nuclear and Magnetic Small-Angle Neutron Scattering Data
KE Yubin1,2(), LI Bin3, DUAN Huiping3()
1 Spallation Neutron Source Science Center, Dongguan 523803, China
2 Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China
3 School of Materials Science and Engineering, Beihang University, Beijing 100191, China
引用本文:

柯于斌, 李彬, 段辉平. 利用小角中子核磁散射分离研究AerMet100钢中纳米析出相的形貌和成分[J]. 金属学报, 2024, 60(8): 1109-1118.
Yubin KE, Bin LI, Huiping DUAN. Morphology and Chemical Composition of Nanoprecipitate in AerMet100 Steel by Separation of the Nuclear and Magnetic Small-Angle Neutron Scattering Data[J]. Acta Metall Sin, 2024, 60(8): 1109-1118.

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摘要: 

AerMet100超高强度钢以其优异的力学性能广泛应用于飞机起落架。其超高强度主要源于合金回火过程中产生的大量M2C型针状析出相的二次硬化作用。由于AerMet100高强钢中的纳米析出相与马氏体基体共格且尺寸细小,无法进行萃取,很难采用传统成像手段对其尺寸和成分进行准确表征。本工作结合TEM和XRD的观测结果,采用小角中子散射(SANS)技术分别对454、482、486和498℃回火5 h的AerMet100合金钢中M2C型针状析出相的尺寸、分布和含量进行了定量表征。通过在SANS实验时施加1.1 T横向磁场并对数据沿平行和垂直磁场方向按角度规约,实现了对数据的核、磁散射分离。对核散射曲线的模型拟合结果显示,合金中针状析出相平均长度为6~16 nm,平均直径为1~2 nm,针状碳化物相的体积分数随退火温度升高由0.54%逐渐提高至5.19%。磁散射数据得到的碳化物结构参数均大于核散射结果,说明在碳化物与马氏体基体相界面存在自旋错排的纳米磁畴区。此外,通过对碳化物和基体相中子核磁散射长度密度的对比计算,推断出针状碳化物的可能的化学组成和密度分别为:(Cr0.4Mo1.6)C和8.55 g/cm3

关键词 AerMet100钢纳米析出相小角中子散射核磁散射分离纳米相化学成分    
Abstract

AerMet100 ultrahigh-strength steel is widely used in aircraft landing gears because of its excellent mechanical properties. Its high strength mainly results from the secondary hardening effect of a large amount of needle-shaped M2C-type precipitates generated during the alloy tempering process. Given the nanoscale size and coherency with the martensitic matrix, the size and composition of the precipitates in the AerMet100 steel are difficult to extract and accurately characterize by using traditional imaging techniques. In this study, the size, distribution, and composition of M2C-type needle-like precipitates in AerMet100 steel tempered for 5 h at 454, 482, 486, and 498oC were quantitatively characterized by combining TEM, XRD, and small-angle neutron scattering (SANS) techniques. By applying a transverse magnetic field of 1.1 T during the SANS experiment and reducing the data along the parallel and perpendicular magnetic field directions, the separation of nuclear and magnetic scattering data was achieved. Model fitting of the nuclear scattering curves revealed an average length of 6-16 nm and an average diameter of 1-2 nm for the needle-like precipitates in the alloy. The volume fraction of the needle-like phase increases with the tempering temperature ranging from 0.54% to 5.19%. Given the nanodomains between the precipitates and matrix phase with spin misalignment, the structural parameters obtained from magnetic scattering data are much bigger than the nuclear ones. Furthermore, by comparing the neutron scattering length densities of the carbides and matrix phases, the possible chemical composition and physical density of the needle-like precipitates within are (Cr0.4Mo1.6)C and 8.55 g/cm3, respectively. This study demonstrates nondestructive quantitative neutron scattering analysis of the nanoscale morphology and chemical composition of nanophases in ferromagnetic alloys.

Key wordsAerMet100 steel    nanoscale precipitate    small-angle neutron scattering    separation of nuclear and magnetic scattering    chemical composition of nanophase
收稿日期: 2024-03-01     
ZTFLH:  TG142  
基金资助:国家重点研发项目(2021YFB3501201);国家自然科学基金项目(12275154);广东省基础与应用基础研究基金项目(2021B1515140028);中国科学院青年创新促进会人才项目(2020010)
通讯作者: 柯于斌,keyb@ihep.ac.cn,主要从事中子散射方法学研究及其多学科应用方面的研究段辉平,hpduan@buaa.edu.cn,主要从事电子显微分析及合金构效关系的研究
Corresponding author: KE Yubin, associate professor, Tel: (0769)88931334, E-mail: keyb@ihep.ac.cnDUAN Huiping, professor, Tel: (010)82339822, E-mail: hpduan@buaa.edu.cn
作者简介: 柯于斌,男,1984年生,副研究员,博士
图1  CoNi_454样品透过率曲线的Bragg边,及沿0°和90°方向按10°角进行积分和规约
图2  486和498℃回火5 h的AerMet100钢显微组织的TEM像及选区电子衍射(SAED)花样
图3  AerMet100回火钢的XRD谱
图4  AerMet100钢回火处理后沿基体不同晶体学取向的针状M2C析出相形貌的TEM像及SAED花样
图5  不同温度回火处理AerMet100钢的磁滞回线,及无磁场(电磁铁5 mT剩磁)和1.1 T磁场条件下AerMet100钢小角中子散射(SANS)一维散射曲线
PhaseChemical compositionDensity / (g·cm-3)ρN / (1010 cm-2)ρM / (1010 cm-2)
Martensite lath matrixFe70.92Co13.4Ni11.1Cr3.1Mo1.2C0.23Ti0.057.626.844.43
Reverse austenite filmFe70.92Co13.4Ni11.1Cr3.1Mo1.2C0.23Ti0.057.596.740
Needle-like carbide(Cr x Mo y )CUnknown5.210
Tempered particleFe3Mo3C9.176.52-
表1  AerMet100钢组成相的成分、密度及中子散射长度密度
图6  不同磁场加载下498℃回火AerMet100钢的二维SANS散射花样
图7  1.1 T磁场加载下AerMet100回火钢的SANS实验观测结果,核散射和拟合曲线,磁散射和拟合曲线,以及核磁散射比值曲线
SampleD / nmL / nmRHS / nmfV / %
CoNi_4541.15 ± 0.766.00 ± 1.275.95 ± 1.050.54 ± 0.15
CoNi_4822.02 ± 1.049.63 ± 0.876.68 ± 0.922.47 ± 0.34
CoNi_4862.37 ± 0.7510.6 ± 1.726.75 ± 0.783.25 ± 0.38
CoNi_4982.48 ± 0.9915.9 ± 2.947.07 ± 0.935.19 ± 0.68
表2  AerMet100钢SANS核散射拟合结果
SampleDLRHSt
CoNi_4541.80 ± 0.746.51 ± 0.425.01 ± 0.470
CoNi_4822.46 ± 0.7513.70 ± 1.2418.50 ± 0.412.59 ± 0.47
CoNi_4862.60 ± 0.8613.40 ± 1.5018.00 ± 0.355.56 ± 1.60
CoNi_4982.62 ± 0.4019.07 ± 1.6118.57 ± 0.465.57 ± 1.56
表3  AerMet100钢SANS磁散射拟合结果 (nm)
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