Short-range order in α-Fe–Si single crystals

Magnetism and origin of non-monotonous concentration dependence of the bulk modulus in Fe-rich alloys with Si, Ge and Sn: a first-principles study

“…Moreover, although the lattice constant of the A2 phase also decreases, the rate of the changes is only negligibly smaller if compared to experiment [4], so that this decrease may be viewed as a consequence of the ordering in realistic samples. We emphasize this point here because: (i) for the discussion of the experimental results (see, e.g., [3]) it is sometimes assumed that Si has a smaller atomic radius than Fe and that this in some way may explain a reduction in the moments of Fe atoms neighbouring the Si sites; (ii) earlier first-principles CPA studies of Fe-Si were performed either without lattice constant optimization [17] or they considered only the A2 phase [18]. Indeed, pure Si with a diamond structure and, more relevant in this context, hypothetical metallic bcc Si (see [29] and the results presented in the next section) both have an atomic volume larger than pure bcc Fe.…”

“…The magnetic properties and their dependence on the Si content were the subject of numerous theoretical models, starting from Neel's hypothesis [9] about oriented ordering of the Si atoms in Fe-Si, which only recently seems to have been confirmed experimentally [3], and phenomenological models by Niculescu et al [10] and Elsukov et al [11]. These models rely mainly on assumptions relating the Fe moments to the local chemical environment.…”

“…Despite the fact that the knowledge of the calculated electronic structure and site distribution of magnetic moments in ordered Fe 3 Si can be useful to draw some rough qualitative conclusions about the physical situation in disordered Fe-Si alloys with lower Si content, more insight can be provided only by calculating the electronic structure for realistic disordered alloys in the actual chemical composition. Moreover, as will be shown in this paper, the concentration dependence of some properties, like the bulk modulus of Fe-Si alloys in the range between 0 and 25 at.% Si, cannot be considered just as an interpolation between highly diluted Fe-Si alloys and the Fe 3 Si compound.…”

Ближний порядок в магнитомягком сплаве alpha-FeAl

“…Результаты исследова-ний локальной структуры кристаллов железо-кремний, содержащих от 5 до 10 at.% Si, с помощью рентге-новской дифракции и ЯГР-спектроскопии приведены в работах [54][55][56][57]. Впервые показано, что для всех кон-центраций кремния характерно ближнее упорядочение B2-типа в ОЦК-решетке сплавов, которое в случае x ≥ 0.08 сосуществует с кластерами D0 3 -фазы.…”

“…Смещение максимума из расчетного положения может быть обусловлено де-формацией решетки в окружении растворенных атомов алюминия. Аналогичное смещение сверхструктурных пиков наблюдалось в железокремнистых сплавах [54,55]. Особенности диффузного рассеяния в сплавах Fe-Si объяснялись присутствием кластеров, состоящих из двух ОЦК-ячеек, которые центрированы атомами кремния и имеют общую грань.…”