Abstract
A new phase has been found in the rapidly solidified V-Ni-Si alloy which is isostructural with the C phase in the V-Co-Si system. High-resolution electron microscopy and selected-area electron diffraction were used to study the domain structures and planar defects, and corresponding structural models are proposed. It is found that the C14 Laves phase always occurs at the domain boundary of the C phase and there is very little distortion at the interphase boundary. Sometimes five-member rings can also be observed at the domain boundary, which may be responsible for the often observed ten-member clusters in the severely disordered area of the C phase. Moreover, the modulated structures introduced by planar faults and the intersection of these faults are also discussed.