A body-centred tetragonal twin martensite was found in Co39Ni33Al28 ferromagnetic shape memory alloy by means of transmission electron microscopy. The twin lamellae had Σ = 25 (01¯1) twin boundaries and [011]||(01¯1) slip system. A periodic appearance of the twin lamellae resulted in a modulated structure with a repeat periodicity of 56d 01¯1 perpendicular to the twin interface. The twinning mechanism during martensite transformation was considered.

TEM Characterization of Twinning in Co39Ni33Al28 Alloy. H.Y.Wang, K.Wang, Z.H.Liu, Y.G.Wang, G.H.Wu, X.F.Duan: Materials Transactions, 2007, 48[8], 2139-42