动态预压缩对CoCrFeNiMn高熵合金微尺度压入硬度的影响

许海涛; 邱吉; 肖革胜; 姚永永; 树学峰

doi:10.11858/gywlxb.20210773

动态预压缩对CoCrFeNiMn高熵合金微尺度压入硬度的影响

doi: 10.11858/gywlxb.20210773

太原理工大学机械与运载工程学院应用力学研究所，山西太原　030024

基金项目: 国家自然科学基金（11772217）；山西省自然科学基金（201801D121015）

详细信息

作者简介:
许海涛（1995－），男，硕士研究生，主要从事弹塑性力学研究. E-mail：18435152022@163.com

通讯作者:
树学峰（1964－），男，教授，主要从事弹塑性力学研究. E-mail：shuxuefeng@tyut.edu.cn

中图分类号: O347
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出版历程
- 收稿日期: 2021-04-13
- 修回日期: 2021-05-19

Effect of Dynamic Pre-Compression on Micro-Scale Indentation Hardness of CoCrFeNiMn High-Entropy Alloy

Institute of Applied Mechanics, School of Mechanical and Transportation Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi, China

摘要

摘要: 高熵合金具有优异的力学性能，如高硬度、高强度、优良的耐磨能力，以及优异的磁性能、高电阻率、高温力学和抗氧化性能等，因此具有非常广阔的应用前景。在高熵合金的应用中会出现合金内部预存塑性应变的情况，然而人们对高熵合金塑性变形后的力学性能研究较少，如微尺度压缩下的硬度等。在微压入测试中，由于存在尺度效应，需要采用相应的微压入测试理论来剔除尺度效应的影响。为此，采用分离式霍普金森压杆对CoCrFeNiMn高熵合金进行室温和高温（600、800、1000 ℃）动态预压缩，使合金具有不同的预压缩塑性应变，采用描述尺度效应的Nix-Gao微尺度压入理论模型，对不同塑性变形的动态预压缩样品在微尺度下的硬度进行表征。结果表明：在宏观预压缩下，不同的塑性变形对合金的微尺度压入硬度具有显著的影响，与轴向压缩相比，径向压缩下剔除尺度效应的硬度更大。该研究方法建立了宏观塑性变形与微尺度压入硬度之间的联系，也为实现通过微尺度压入测试判定材料内部塑性变形提供了新思路。
- 高熵合金 /
- 动态预压缩 /
- 尺度效应 /
- 硬度
Abstract: High-entropy alloys have excellent mechanical properties, such as high hardness, high strength, high resistivity, excellent wear resistance, excellent magnetic properties, and high-temperature mechanical and oxidation resistance. This also makes high-entropy alloys have a very broad application prospects. In the application of high-entropy alloys, there will be pre-existing plastic strains in the alloys. However, the mechanical properties of plastic deformed high-entropy alloys (such as the hardness under micro-scale compression) were less studied. In the micro-indentation test, it is necessary to eliminate the influence of the scale effect by adopting the corresponding micro-indentation test theory. Dynamic pre-compressions of CoCrFeNiMn high-entropy alloy at room temperature and high temperature (600, 800, 1000 ℃) were performed with split Hopkinson pressure bar in this paper, so that the alloy has different pre-compression plastic strains, and Nix-Gao which describes the scale effect is adopted. The hardness of dynamic pre-compression specimens with different plastic deformations was characterized at the micro-scale with the micro-scale indentation theory model. The results show that different plastic deformations under macro-precompression have a significant effect on the micro-scale indentation hardness of the alloy. Compared with axial compression, the hardness that eliminates the scale effect is greater than that of sample under radial compression. This research method establishes the relationship between the macroscopic plastic deformation and the micro-scale indentation hardness, and also provides a new idea for the realization of the micro-scale indentation test to determine the research method of the internal plastic deformation of materials.
- high-entropy alloy /
- dynamic pre-compression /
- scale effect /
- hardness

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图 1 CoCrFeNiMn高熵合金样品

Figure 1. CoCrFeNiMn high-entropy alloy sample

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图 2 CoCrFeNiMn 高熵合金的能谱

Figure 2. Energy spectrum (EDS) of CoCrFeNiMn high-entropy alloy

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图 3 CoCrFeNiMn高熵合金的电子背散射衍射反极图与XRD谱

Figure 3. Electron backscatter diffraction inverse pole figure and XRD pattern of CoCrFeNiMn high-entropy alloy

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图 4 动态预压缩后的样品

Figure 4. Samples after dynamic pre-compression

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图 5 纳米压痕测试点阵局部示意图

Figure 5. Partial schematic of nanoindentation test dot matrix

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图 6 纳米压入实验的载荷-深度曲线

Figure 6. Load-depth curve in nanoindentation experiment

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图 7 CoCrFeNiMn高熵合金的轴向压缩载荷-深度曲线

Figure 7. Load-depth curves of CoCrFeNiMn high-entropy alloy in axial compression

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图 8 CoCrFeNiMn高熵合金的径向压缩载荷-深度曲线

Figure 8. Radial compression load-depth curves of CoCrFeNiMn high-entropy alloy

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图 9 CoCrFeNiMn高熵合金轴向压缩的刚度-深度曲线

Figure 9. Stiffness-depth curves of CoCrFeNiMn high-entropy alloy in axial compression

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图 10 CoCrFeNiMn高熵合金径向压缩的刚度-深度曲线

Figure 10. Radial compression stiffness-depth repeatability curves of CoCrFeNiMn high-entropy alloy

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图 11 CoCrFeNiMn高熵合金的硬度-深度曲线

Figure 11. Hardness-depth curve of CoCrFeNiMn high-entropy alloy

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图 12 纳米压入测试中室温动态预压缩样品的H²与1/h的关系

Figure 12. Relationship between H² and 1/h of the room temperature dynamic pre-compression samples in the nanoindentation test

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图 13 纳米压入测试中高温动态预压缩样品的H²与1/h的关系

Figure 13. Relationship between H² and 1/h of the high-temperature dynamic pre-compression sample in the nanoindentation test

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表 1 室温动态预压缩下不同塑性变形对应的剔除尺度效应的硬度

Table 1. Scale effect elminated hardness of different plastic deformationsunder dynamic pre-compression at room temperature

Plastic strain/% H₀/GPa
Axial compression Radial compression

23 3.06 3.22
40 3.72 4.05
47 3.98 4.28

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表 2 高温动态预压缩下不同塑性变形对应的剔除尺度效应的硬度

Table 2. Scale effect eliminated hardness of different plastic deformations under high temperature dynamic pre-compression

Plastic strain/% H₀/GPa
Axial compression Radial compression

51 3.70 3.92
61 3.28 3.54
72 2.96 2.69

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