In this thesis, an attempt has been made to synthesis the nanostructured Ni 47 Mn 40 Sn 13 ferromagnetic shape memory alloy by using mechanical alloying. Milling of Ni, Mn and Sn powders was carried out in planetary ball mill for 20 hours. The structure and magnetic evaluation of samples were investigated by X-ray diffraction, Dc magnetization and AC susceptibility measurements. Rietveld analysis indicates 20 hours milled sample has a L2 1 phase. In this sample, the martensitic transformation (MT) was not observed. This is basically due to the atomic disorder and large lattice strain of nanoparticles. As-milled powder samples were sealed in the quartz tubes under high vacuum and subjected to heat treatments at 550°C, 750°C, and 950°C for 16 hours followed by rapid quenching in ice-water mixture. In samples annealed in 550°C and 750°C minor additional peaks in the diffraction pattern was observed. In the sample that annealed at 550°C, martensitic transformation not founded because this sample has the critical lattice parameter. It should be emphasize that the MT was seen in other the annealed samples. The obtained results show that the MT of Ni-Mn-Sn alloy can be modified by changing the heat treatment process. In addition magnetocaloric effect (MCE) of sample annealed at 950°C was investigated by M (H) measurements. Difference between saturated magnetization of austenite and martensite phase cause large magnetic entropy change around martensitic transformation. The measurements show that this alloy has a good MCE. Therefore, it will be an appropriate candidate for magnetic refrigerant.
