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磁性高熵合金在能量转换、磁滞电机、电磁控制机构等相关领域具有一定的应用前景. 采用选区激光熔化(SLM)成形技术在不同工艺参数下制备出AlCoCrCuFeNi高熵合金, 对合金的相组成、微观组织结构、磁性能和微观力学行为进行了系统的研究. 结果表明, SLM成形态合金主要由体心立方(BCC)基体相和少量近似球形的面心立方(FCC)纳米析出相组成, 其纳米硬度随着激光功率的增加而减小, 随着扫描速度的变化在一定范围波动, 但是整体均呈现出优异的微观力学性能, 且其纳米压痕蠕变变形机制异于传统经典蠕变理论, 主要受位错运动控制. SLM成形态合金均表现出典型的半硬磁特性, 其饱和磁化强度受SLM工艺参数影响较小, 保持在43 A·m2/kg左右; 矫顽力随着激光功率的增加从1.72 kA/m增加到2.71 kA/m, 随着扫描速度的增加从2.37 kA/m减小到1.98 kA/m. 磁性能研究表明, 该成形态AlCoCrCuFeNi高熵合金的磁性能有望广泛应用于磁控机构等领域. 本工作可为后续优化SLM高熵合金的综合磁学性能以及纳米压痕室温蠕变机制提供一定的理论基础和实实验方向.
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关键词:
- 选区激光熔化 /
- AlCoCrCuFeNi高熵合金 /
- 半硬磁特性 /
- 微观力学
Magnetic high-entropy alloy (HEA) has certain application prospects in the fields of energy conversion, hysteresis motor, electromagnetic control mechanism and others. In this study, AlCoCrCuFeNi HEA is prepared by selective laser melting (SLM) with different process parameters, and the phase composition, microstructure, magnetic properties and micromechanical behavior are studied systematically. The results show that the SLMed alloy mainly consists of a BCC matrix phase with a small quantity of approximately spherical FCC precipitated nanophase. The nanohardness decreases with the increase of laser power and fluctuates in a certain range with the change of scanning speed, but the whole sample shows excellent micromechanical properties. Besides, it is found that the room-temperature nanoindentation creep deformation mechanism of AlCoCrCuFeNi HEAs is mainly controlled by dislocation motion, which is different from the results given by the traditional classical creep theory. Both of SLMed alloys exhibit typical semi-hard magnetic properties. The saturation magnetization is affected slightly by the SLM process parameters and remains at about 43 A·m2/kg because all samples have a similar quantity of ferromagnetic elements (Fe,Co and Ni). However, the coercivity increases from 1.72 to 2.71 kA/m with the increase of laser power (P), and decreases from 2.37 to 1.98 kA/m with the increase of scanning speed (v), which can be attributed to the different effects of porosity and internal stress on the pinning of domain walls under different process parameters (P and v). This work provides a theoretical basis and experimental direction for further studying the optimization of comprehensive magnetic properties and the room temperature creep mechanism of SLMed high-entropy alloy.-
Keywords:
- selective laser melting /
- AlCoCrCuFeNi high-entropy alloy /
- semi-hard magnetic property /
- micro-mechanical behavior
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Elements Al Co Cr Cu Fe Ni Mass fraction/% 8.85 18.86 16.59 20.28 17.25 18.11 density/(g·mm–3) 2.7 8.85 7.75 8.90 7.87 8.85 Melting point/K 933 1770 2123 1356 1811 1728 Average atomic/nm 0.1432 0.1363 0.1249 0.1280 0.1270 0.1240 Structure FCC HCP BCC FCC BCC FCC VEC* 3 9 6 11 8 10 *VEC—valence electron concentration. 
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工艺参数 取值 Laser thickness (t)/μm 40 Laser power (P)/W 110—150 Scan velocity (v)/(mm·s–1) 1350—1550 Hatch spacing (h)/μm 50
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P/W VBCC/% VFCC/% aBCC/Å aFCC/Å 110 94.89 5.11 2.8709±0.0006 3.6100±0.0006 120 94.38 5.62 2.8726±0.0017 3.6280±0.0007 130 94.24 5.76 2.8752±0.0012 3.6289±0.0017 140 93.41 6.59 2.8762±0.0011 3.6310±0.0023 150 92.04 7.96 2.8763±0.0006 3.6367±0.0014
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v/(mm·s–1) VBCC/% VFCC/% aBCC/(Å aFCC/Å 1350 94.84 5.16 2.8840±0.0029 3.6460±0.0012 1400 94.89 5.11 2.8825±0.0012 3.6289±0.0017 1450 93.75 6.25 2.8810±0.0034 3.6430±0.0006 1500 94.13 5.87 2.8773±0.0015 3.6358±0.0021 1550 93.62 6.38 2.8737±0.0009 3.6297±0.0024
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P/W Hmax /nm Nano-hardness/GPa E/GPa 110 321.5±13.8 8.8±0.9 202.3±8.4 120 322.4±2.1 8.7±0.2 202.5±6.7 130 323.2±13.6 8.7±0.8 208.9±15.6 140 326.8±6.2 8.5±0.5 201.8±2.3 150 332.3±8.4 8.2±0.5 203.8±5.0
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v/(mm·s–1) Hmax /nm Nano-hardness/GPa E/GPa 1350 331.0±6.3 8.2±0.4 199.2±10.9 1400 323.2±13.6 8.7±0.8 208.9±15.6 1450 322.3±3.8 8.8±0.2 201.7±8.6 1500 338.7±8.5 7.7±0.4 197.0±7.7 1550 332.3±8.4 8.1±0.5 193.3±5.0
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