The preparation of oriented samples of ferromagnetic shape memory alloy CoNiAl

摘要

In the present study, the set of the directionally solidified samples from alloy with the nominal composition Co_(38)Ni_(33)Al_(29) were prepared using the Bridgman and the floating zone method. Various growth rates results in various solidification structures, mainly different ratio of the disordered phase γ-cobalt solid solution and the ordered phase β-B2 (Co.Ni)Al. The ratio has the fundamental effect on the temperature of the martensitic phase transition. This evolution of the samples structure was studied by metallography, SEM, EPMA and EBSD methods. The results are discussed in the frame of decomposition kinetics of this ternary alloy. The samples without high-angle grain boundaries, i.e., single-crystals, can be cut from the prepared directional grown ingots and used to examine mechanical properties.