Al<i><sub>x</sub></i>CoCrFeNi高熵合金力学性能的分子动力学模拟

张路明; 马胜国; 李志强; 辛浩

doi:10.11858/gywlxb.20210730

Al_xCoCrFeNi高熵合金力学性能的分子动力学模拟

doi: 10.11858/gywlxb.20210730

张路明^{1, 2,},
马胜国^{1, 2},
李志强^{1, 2},
辛浩^{1, 2,*, ,}

1.
太原理工大学应用力学研究所，山西太原　030024
2.
山西省结构冲击与材料强度重点实验室，山西太原　030024

基金项目: 国家自然科学基金（11972244）；山西省应用基础研究计划（201901D111088）

详细信息

作者简介:
张路明（1997－），男，硕士研究生，主要从事分子动力学研究.E-mail：zhangluming0036@link.tyut.edu.cn

通讯作者:
辛　浩（1985－），男，副教授，主要从事新型材料力学性能的分子动力学研究.E-mail：xinhao@tyut.edu.cn

中图分类号: O344.3; O521.2
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出版历程
- 收稿日期: 2021-03-04
- 修回日期: 2021-04-07

Mechanical Properties of Al_xCoCrFeNi High-Entropy Alloy: A Molecular Dynamics Study

ZHANG Luming^{1, 2
,},
MA Shengguo^{1, 2},
LI Zhiqiang^{1, 2},
XIN Hao^{1, 2,*
, ,}

1.
Institute of Applied Mechanics, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China
2.
Shanxi Key Laboratory of Material Strength and Structural Impact, Taiyuan 030024, Shanxi, China

摘要

摘要: 通过分子动力学方法模拟了原子尺度下高熵合金的制备过程，对AlCoCrFeNi进行了微观组织分析，研究了温度和Al含量变化时AlCoCrFeNi高熵合金在轴向载荷作用下的力学性能。模拟结果显示：Al_xCoCrFeNi高熵合金在拉伸过程中依次经历弹性—屈服—塑性阶段。屈服后，材料开始出现位错，随之出现层错和孪晶；随着位错的不断产生和湮灭，材料产生了不均匀塑性变形。分析显示：Al与其他元素的原子半径差产生的晶格畸变效应以及Al与其他原子的结合力影响了高熵合金的杨氏模量和屈服应力；温度升高导致金属原子间的热振动加剧，原子动能增加，原子间的距离增大，原子间的结合力下降，致使合金的弹性模量和屈服应力下降，温度的净效应类似于晶格畸变。
- 高熵合金 /
- 分子动力学 /
- 拉伸 /
- 温度 /
- 铝含量
Abstract: The fabrication process of the high-entropy alloys (HEAs) at the atomic scale was investigated numerically through molecular dynamics (MD) approach, with which the micro-structures of Al_xCoCrFeNi were analyzed. The mechanical properties of the fabricated specimens with different Al contents subjected to axial loads were explored at different temperatures. Numerical results show that the high-entropy alloys Al_xCoCrFeNi undergoes the elastic, yielding and plastic stages in order when subjected to tensile. After yielding, dislocation lines emerge in the material, followed by the stacking faults and twins. The material produces inhomogeneous plastic deformation with the continuous generation and disappearance of dislocations. This analysis suggest that the lattice distortion effect is induced by the radius difference between Al atoms and other atoms, additionally, the binding force between them affects the Young's modulus and yield stress of high-entropy alloys. Moreover, the increase of temperature leads to more severe thermal vibration between metal atoms, larger atomic dynamic energy, increasing distance between atoms, while decreasing binding force between atoms, thereby resulting in a decrease of alloy elastic modality and yield stress. The effect of temperature is similar to that of the lattice distortion.
- high-entropy alloys /
- molecular dynamics /
- stretching /
- temperature /
- aluminum content

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图 1 AlCoCrFeNi模型及原子结构

Figure 1. Model and atomic structure of AlCoCrFeNi HEA

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图 2 Al_0.1CoCrFeNi在拉伸加载下的应力-应变曲线

Figure 2. Stress-strain relations of Al_0.1CoCrFeNi under tensile loading

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图 3 不同拉伸应变下Al_0.1CoCrFeNi高熵合金的微观结构

Figure 3. Micro-structure of Al_0.1CoCrFeNi HEA under different strains

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图 4 不同拉伸应变下Al_0.1CoCrFeNi高熵合金的位错演化

Figure 4. Dislocation evolution of Al_0.1CoCrFeNi HEA under different strains

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图 5 300 K下不同Al含量的径向分布函数

Figure 5. RDF at 300 K under different Al concentrations

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图 6 不同Al含量时径向分布函数的半峰全宽

Figure 6. FWHM of RDF under different Al concentrations

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图 7 不同Al含量下Al_xCoCrFeNi的拉伸应力-应变曲线

Figure 7. Tensile stress-strain curves of Al_xCoCrFeNi under different Al concentrations

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图 8 不同温度下Al_0.1CoCrFeNi的拉伸应力-应变曲线

Figure 8. Tensile stress-strain curves of Al_0.1CoCrFeNi under different temperatures

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图 9 不同温度下模型达到弹性极限的CNA图

Figure 9. CNA diagram of the model reaching the elastic limit at different temperatures

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图 10 不同温度下杨氏模量和拉伸强度的变化

Figure 10. Young’s modulus and tensile strength at different temperatures

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表 1 不同原子的半径

Table 1. Radius of different atoms Å

Al	Co	Cr	Fe	Ni
1.43	1.25	1.24	1.24	1.24

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表 2 晶格常数、混合熵、混合焓、熔化相互作用参数及原子尺寸差

Table 2. Lattice constants, entropy of mixing, enthalpy of mixing, regular melt interaction parameter, and atomic-size difference

Alloy	Lattice constant/nm	${\Delta }{S}{_{ {\rm{mix} }} }$/(J·mol⁻¹·K⁻¹)	${\Delta }{H}{_{\rm{mix} } }/(\mathrm{k}\mathrm{J} \cdot {\mathrm{m}\mathrm{o}\mathrm{l} }{^{-1}})$	$ \varOmega $	$\delta /\text{%}$
CoCrFeNi	0.3580	11.53	−3.75	5.71	1.06
Al_0.25CoCrFeNi	0.3592	12.71	−6.25	3.40	3.25
Al_0.50CoCrFeNi	0.3603, 0.2875	13.15	−9.09	2.55	4.22
Al_0.75CoCrFeNi	0.3603, 0.2877	13.33	−10.90	2.09	4.83
AlCoCrFeNi	0.2879	13.38	−12.32	1.83	5.25

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表 3 Al_xCoCrFeNi高熵合金中Al含量、各元素原子个数及模型体积和密度

Table 3. Al concentration, atomic number of each element and bulk and density of the model in Al_xCoCrFeNi HEA

x	x_Al/%	Atomic number					Volume/(10⁻³⁰ m³)	Density/(g·cm⁻³)
x	x_Al/%	Al	Co	Cr	Fe	Ni	Volume/(10⁻³⁰ m³)	Density/(g·cm⁻³)
0.1	2.4	2250	23703	23184	23439	23424	1088008.3	8.160
0.3	7.0	6948	21903	22902	22059	22188	1107889.7	7.799
0.5	11.1	10959	20898	21924	21123	21096	1126321.6	7.497
0.7	14.9	14616	19998	20895	20331	20160	1144551.1	7.222
1.0	20.0	19047	19092	19641	19035	18915	1170662.1	6.856

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表 4 Al_xCoCrFeNi在单轴拉伸加载下的力学性能

Table 4. Mechanical properties of Al_xCoCrFeNi under uniaxial tensile loading

x	E/GPa	Y/GPa	$\varepsilon $_Y
0.1	115.29	14.638	0.131
0.3	97.65	11.372	0.117
0.5	86.95	8.809	0.103
0.7	76.88	6.738	0.089
1.0	64.18	4.510	0.071

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表 5 不同温度下Al_0.1CoCrFeNi在单轴拉伸载荷下的力学性能

Table 5. Mechanical properties of Al_0.1CoCrFeNi under uniaxial tensile loading at different temperatures

T/K	E/GPa	Y/GPa	$ \varepsilon$_Y
77	116.74	16.098	0.140
300	115.29	14.638	0.131
500	110.92	13.169	0.123
700	104.71	11.596	0.113
1000	95.82	9.521	0.102

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