Single crystals of Co50Ni20FeGa29 with B2 phase have been obtained in a deep supercooling condition. The in terface-facets and the segregation effect lead to the formation of ordered defects that store a directional internal stress. These defects give to a large energy barrier that leads to a very sharp martensitic transformation within a temperature window of only 2K. The single crystals show good shape memory effect and superelasticity, which are anisotropic between the growth direction [001] and its equivalent direction [010]. The anisotropic behaviors are attributed to the directional internal stress caused by the ordered defects. (c) 2006 Elsevier B.V. All rights reserved.