Direct Evidence of the Hume-Rothery Stabilization Mechanism in Al-Mn-Fe-Si Mackay-Type 1/1-Cubic Approximants
Direct Evidence of the Hume-Rothery Stabilization Mechanism in Al-Mn-Fe-Si Mackay-Type 1/1-Cubic Approximants
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Al-Mn-Fe-Si Mackay 型 1/1 立方近似中休谟-罗瑟稳定机制的直接证据
DOI：
10.2320/matertrans.42.933
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发表时间：
2001
影响因子：
1.2
通讯作者：
U. Mizutani
中科院分区：
文献类型：
--
作者：
T. Takeuchi;T. Onogi;E. Banno;U. Mizutani
通过将 Rietveld 方法应用于同步辐射 X 射线源获取的 X 射线粉末衍射光谱，对一系列 Al-Mn-Fe-Si 麦凯型 1/1 立方近似体进行了详细的结构分析。我们发现相同的麦凯团簇占据了立方晶格的体心和顶点位置，但连接麦凯团簇的胶位点中的原子分布对于每种合金来说都是独特的。每个晶胞的 s、p 电子数是通过将适当数量的价电子分配给细化原子结构中涉及的组成原子来计算的。结果表明，当 Fe 原子取代 Mn 原子时，每个晶胞的 s、p 电子总数保持不变，并且始终以满足所谓的休谟-罗瑟里匹配规则的值为中心，其中费米球与相关的布里渊区平面很好地重合。我们得出的结论是，休谟-罗瑟里匹配条件通过胶位中空位数量的增加来补偿由于 Fe 原子取代 Mn 原子而导致的价电子增加，从而稳定了三元 Al-Mn-Fe-Si 近似。
The detailed structure analysis for a series of the Al–Mn–Fe–Si Mackay-type 1/1-cubic approximants has been performed by applying the Rietveld method to the x-ray powder diffraction spectra taken with a synchrotron radiation x-ray source. We found that identical Mackay clusters occupy both the body-center and vertex positions of the cubic lattice but that atom distributions in glue sites connecting the Mackay clusters are unique to each alloy. The number of s, p-electrons per unit cell is calculated by assigning the appropriate number of valence electrons to constituent atoms involved in the refined atomic structure. It is shown that, when the Fe atoms are substituted for Mn atoms, the total number of s, p-electrons per unit cell remains unchanged and is always centered at a value satisfying the so called Hume-Rothery matching rule, where the Fermi sphere well coincides with the relevant Brillouin zone planes. We conclude that the Hume-Rothery matching condition stabilizes the ternary Al–Mn–Fe–Si approximants by compensating an increase in the valence electrons due to the replacement of Mn atoms by Fe atoms by an increase in the number of vacancies in the glue sites.