Friák Martin, Holec David, Šob Mojmír
Institute of Physics of Materials, Academy of Sciences of the Czech Republic, Žižkova 22, CZ-616 62 Brno, Czech Republic.
Department of Materials Science, Montanuniversität Leoben, Franz-Josef-Strasse 18, A-8700 Leoben, Austria.
Nanomaterials (Basel). 2018 Dec 15;8(12):1057. doi: 10.3390/nano8121057.
We applied first-principles electronic structure calculations to study structural, thermodynamic and elastic properties of nanocomposites exhibiting nearly perfect match of constituting phases. In particular, two combinations of transition-metal disilicides and one pair of magnetic phases containing the Fe and Al atoms with different atomic ordering were considered. Regarding the disilicides, nanocomposites MoSi 2 /WSi 2 with constituents crystallizing in the tetragonal C11 b structure and TaSi 2 /NbSi 2 with individual phases crystallizing in the hexagonal C40 structure were simulated. Constituents within each pair of materials exhibit very similar structural and elastic properties and for their nanocomposites we obtained ultra-low (nearly zero) interface energy (within the error bar of our calculations, i.e., about 0.005 J/m 2 ). The interface energy was found to be nearly independent on the width of individual constituents within the nanocomposites and/or crystallographic orientation of the interfaces. As far as the nanocomposites containing Fe and Al were concerned, we simulated coherent superlattices formed by an ordered Fe 3 Al intermetallic compound and a disordered Fe-Al phase with 18.75 at.% Al, the α -phase. Both phases were structurally and elastically quite similar but the disordered α -phase lacked a long-range periodicity. To determine the interface energy in these nanocomposites, we simulated seven different distributions of atoms in the α -phase interfacing the Fe 3 Al intermetallic compound. The resulting interface energies ranged from ultra low to low values, i.e., from 0.005 to 0.139 J/m 2 . The impact of atomic distribution on the elastic properties was found insignificant but local magnetic moments of the iron atoms depend sensitively on the type and distribution of surrounding atoms.
我们应用第一性原理电子结构计算来研究具有近乎完美匹配组成相的纳米复合材料的结构、热力学和弹性性质。特别地，考虑了过渡金属二硅化物的两种组合以及一对包含具有不同原子排序的铁和铝原子的磁性相。对于二硅化物，模拟了在四方C11b结构中结晶的组分的纳米复合材料MoSi₂/WSi₂以及在六方C40结构中单个相结晶的TaSi₂/NbSi₂。每对材料中的组分表现出非常相似的结构和弹性性质，并且对于它们的纳米复合材料，我们获得了超低（近乎零）的界面能（在我们计算的误差范围内，即约0.005 J/m²）。发现界面能几乎与纳米复合材料中单个组分的宽度和/或界面的晶体学取向无关。就包含铁和铝的纳米复合材料而言，我们模拟了由有序的Fe₃Al金属间化合物和具有18.75 at.%铝的无序Fe-Al相（α相）形成的相干超晶格。这两个相在结构和弹性上都相当相似，但无序的α相缺乏长程周期性。为了确定这些纳米复合材料中的界面能，我们模拟了与Fe₃Al金属间化合物界面处α相中七种不同的原子分布。所得的界面能范围从超低到低值，即从0.005到0.139 J/m²。发现原子分布对弹性性质的影响不显著，但铁原子的局部磁矩敏感地依赖于周围原子的类型和分布。
