Domain structures in rapidly solidified Mn76Fe4Si20 alloys
In the study course of microstructures of the rapidly quenched Mn-Si alloy, 45° rotation twins showing striking eightfold symmetry in the electron diffraction pattern have been reported. These previous investigations interpreted the domain structures in terms of the β-Mn phase. The aim of this work is to show the similar domain structure having pseudo-eightfold symmetry in the reciprocal space in the Mn-Fe-Si system and to ascertain a new structure in the domain structure.The main phase in this alloy is the β-Mn phase with primitive cubic and a=0.63 nm. Fig.l gives the [001] HR image of the β-Mn phase where a square unit cell has been outlined. A planar fault showing projected rectangle network was also seen.The short edge of the rectangle remains to be the same as the a axis of the p-Mn phase, while its long side is equal to . The planar fault could appear repeatedly and form domain structure as shown in Fig.2.