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Series of Ni45.5−xCo4.5Mn36.6In13.4Bx (at.%, x = 0, 0.05, 0.1, 0.5, 1.0) polycrystalline magnetic shape memory alloys were examined in terms of the magnetic properties, structure and transition temperatures. Depending on the boron concentration single or two phase alloys microstructures were observed. Additionally, the martensitic transformation temperatures decreases with the boron addition. Magnetic-field induced transformation occurs for the alloys with the boron addition up to 0.1 at.%. For alloys with 0.5 and 1.0 at.% of B transformation is hindered.

Series of Ni45.5−xCo4.5Mn36.6In13.4Bx (at.%, x = 0, 0.05, 0.1, 0.5, 1.0) polycrystalline magnetic shape memory alloys produced by the induction melting were examined in terms of the structure and transition temperatures. The structure of the alloys was determined by the X-ray diffraction and transmission electron microscopy. Scanning electron microscopy and electron backscattering diffraction techniques were applied to obtain the microstructure and texture of alloys. Boron addition promotes nucleation of the second Co-rich and In-poor phase as well as causes decrease of the martensitic transformation temperatures.

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The crystallization kinetics and structure evolution during annealing of the Ni45.5Co4.5Mn36.6In13.4 (at. %) powders produced by mechanical alloying (MA) was investigated. After 70 h and 100 h of MA, the powder consisted of a mixture of amorphous and nanocrystalline body-centered cubic (bcc) phases. We observed the relaxation in the as-received powder. The relaxation temperature (Tre) increases logarithmically with the annealing time. Annealing above 440 °C results in (1) ordering of L21, (2) dissolution of the residual Ni and Mn, (3) tetragonal MnNi phase formation and (4) γ phases precipitation. The activation energies of the B2 → L21 and Mn (α-Mn) → MnNi (P4/mmm) transformations were calculated.