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基于力磁耦合效应的磁记忆检测技术, 被广泛应用于铁磁性结构件的应力和缺陷检测. 已有研究采用第一性原理针对 α-Fe体系开展了轴向拉压作用下磁矩变化计算, 初步讨论了原子层面的磁检测技术力磁耦合机理. 本文以Fe-C和Fe-Mn掺杂体系为例, 在更为复杂的拉伸、压缩和剪切加载情形下, 深入讨论了 α-Fe材料不同类型原子掺杂体系中磁矩变化等力磁耦合规律机理. 结果表明, α-Fe和掺杂体系在不同类型应变作用下磁矩和能量的变化规律存在不同. 结合态密度、能带结构和原子磁矩的详细分析, 发现掺杂元素通过影响Fe原子的磁矩, 使掺杂体系能带结构的形貌和态密度的峰值发生改变, 进而导致掺杂体系的磁矩和能量变化规律存在差异. 本研究从原子层面考虑了铁磁材料在不同荷载类型、不同掺杂元素和含量下的力磁耦合效应, 是磁记忆检测中多场耦合物理机理的重要补充.Magnetic non-destructive testing technology is widely used to detect stresses and defects in ferromagnetic materials based on the magneto-mechanical coupling effect. In the existing studies, calculated are the magnetic moment variations of the α-Fe system under axial tension and compression by using first-principles study, and the magneto-mechanical coupling mechanism is preliminarily discussed at an atomic level for the magnetic testing technology. In this work, taking the more complex doping systems Fe-C and Fe-Mn for examples, under different loading conditions of tension, compression and shearing, the coupling mechanisms such as the magnetic moment changes in different types of atomic doping systems are discussed in detail. The results show that the α-Fe and doping systems follow different changing laws of magnetic moments and energy under different types of strains. The detailed analyses of the density of states, the band structure, and the atomic magnetic moment show that doping elements change the morphology of band structure and the peak value of density of states by affecting the magnetic moment of Fe atoms, which leads the changing laws of magnetic moment and energy to be different from each other. In this work, discussed are the magneto-mechanical effects on the atomic level for ferromagnetic materials with different loading types, different doping elements and different element content. The results can be used as an important part of the multi-field coupling mechanism for magnetic testing technology.
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Keywords:
- metal magnetic memory/
- testing mechanism/
- α-Fe doping systems/
- strain effect/
- magnetic moment
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] -
Tensile strain Compressive strain Shear strain Strain Magnetic moment/
(${\mu _{\text{B}}}{\cdot\text{ato}}{{\text{m}}^{ - 1}}$)Energy/
eVMagnetic moment/
(${\mu _{\text{B}}}{\cdot\text{ato}}{{\text{m}}^{ - 1}}$)Energy/
eVMagnetic moment/
(${\mu _{\text{B}}}{\cdot\text{ato}}{{\text{m}}^{ - 1}}$)Energy/
eV1% 2.1133 –862.9176 2.1121 –862.9178 2.1150 –862.9175 2% 2.1168 –862.9157 2.1114 –862.9163 2.1265 –862.9152 3% 2.1294 –862.9125 2.1116 –862.9157 2.1498 –862.9112 4% 2.1303 –862.9105 2.1121 –862.9126 2.1878 –862.9063 5% 2.1549 –862.9081 2.1135 –862.9097 2.2195 –862.9006 Energy state Fe(bcc) Fe-C(1) Fe-C(2) Fe-Mn spin-polarized –862.9295 –818.6694 –774.3459 –987.8903 non-spin-polarized –862.4899 –818.5050 –774.3104 –987.8903 ΔE –0.4396 –0.1644 –0.0355 –1×10–5 Structural properties
ofα-Fe (BCC)Lattice constant/
ÅAtomic volume/Å3 Magnetic moment/
(${\mu _{\text{B} } }{\cdot\text{ato} }{ {\text{m} }^{ - 1} }$)Present results 2.833 11.36 2.17 Reference results [25] 2.813 11.13 2.17 [34] 2.83 11.33 2.17 Experimental results [35] 2.87 11.78 2.22 [36] 2.866 11.77 2.12 Strain Tensile strain Compressive strain Shear strain Fe-C(1) Fe-C(2) Fe-Mn Fe-C(1) Fe-C(2) Fe-Mn Fe-C(1) Fe-C(2) Fe-Mn 1% –818.5083 –774.3584 –987.8857 –818.5039 –774.3536 –987.9533 –818.5257 –774.3450 –987.9536 2% –818.5077 –774.3543 –987.8845 –818.4965 –774.3507 –987.9679 –818.5245 –774.3420 –987.9504 3% –818.5016 –774.3457 –987.8827 –818.4882 –774.3469 –987.9711 –818.5186 –774.3372 –987.9446 4% –818.5009 –774.3446 –987.8799 –818.4794 –774.3454 –987.9652 –818.5097 –774.3307 –987.9367 5% –818.4967 –774.3398 –987.8762 –818.4723 –774.3425 –987.9569 –818.5026 –774.3223 –987.9267 Strain Tensile strain Compressive strain Shear strain Fe-C(1) Fe-C(2) Fe-Mn Fe-C(1) Fe-C(2) Fe-Mn Fe-C(1) Fe-C(2) Fe-Mn 1% 2.0433 1.9800 2.1084 2.0031 1.9753 1.9925 2.0299 1.9762 1.9959 2% 2.0887 1.9843 2.1142 1.9645 1.9693 2.1004 2.0242 1.9768 1.9974 3% 2.0887 1.9856 2.1226 1.9175 1.9694 2.1152 1.9566 1.9798 2.0006 4% 2.0927 1.9880 2.1255 1.8791 1.9642 2.1248 1.9564 1.9847 2.0037 5% 2.0952 1.9894 2.1343 1.8573 1.9436 2.1327 1.9444 1.9905 2.0118 -
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