Structural and Magnetic Studies in Ni-Mn-Ga based Ferromagnetic Shape Memory Alloys

Quaternary Ni50FexMn30-xGa20 (x = 2.5, 5, and 15) and Ni45Fe5Mn30Ga20 alloys based on modification of ferromagnetic shape memory alloy ternary Ni50Mn30Ga20 composition prepared by vacuum arc melting and subsequent heat-treatment were investigated to understand the effect of varying Fe-content in Ni-Fe-Mn-Ga alloys. With increasing Fe-content, saturation magnetisation and Curie temperature increased, however martensite transformation temperature did not show a systematic variation. The 57Fe Mossbauer spectra showed three distinct sub-spectra depending upon the site occupancy by Fe-atoms. The results are explained with site selection by Fe-atom in parent L21 lattice.Defence Science Journal, 2011, 61(3), pp.275-284, DOI:http://dx.doi.org/10.14429/dsj.61.64