A Crystallographic Study on the Growth of Partially Faceted MnSn2 Phase during Solidification Process

The growth of MnSn2 phase during the solidification process of Sn-Mn alloy was crystallographically investigated. The results show that the non-faced spherical caps of the MnSn2 crystals follow the continuous growth mechanism to grow rapidly along the direction, while the side surfaces the two-dimensional nucleation mechanism to form the low index {100} and {110} facets. An interface structure analysis indicates that the atom planes within the {100} interplanar spacing period (IPSP) has a lower average reticular density than those within the {011} IPSP. This leads to the faster growth rates and thus the shortening and disappearance of the {100} side facets. As a consequence, the partially faceted (i.e., non-faceted spherical caps and faceted side surfaces) MnSn2 crystals follow an octagonal-base/spherical-cap geometric model (few crystals possess square bases) in three dimensions.