Structure development in Co₃₈Ni₃₃Al₂₉ ferromagnetic shape memory alloy

Abstract
In the present study, a set of the directionally solidified samples from ferromagnetic shape memory alloy with the nominal composition Co₃₈Ni₃₃Al₂₉ was prepared using the Bridgman method. It is shown that various growth rates result in various solidification structures of the crystals, mainly in different ratios of the disordered phase γ cobalt solid solution and the ordered phase β - B2 (Co,Ni)Al. This ratio has the fundamental effect on the temperature of the martensitic phase transition. The results are compared with the structure of samples prepared by the floating zone method. The structures of samples prepared with the different growth rate were studied by metallography, SEM, EDX, and EBSD methods. The samples without high-angle grain boundaries were cut from the prepared crystals for the mechanical testing.