Structural, Magnetic and Transport Properties of Ni-Fe-Al Alloys

Abstract

Abstract. Melt spun ribbons (MSR) of the Ni 55 Fe 20 Al 25 alloy exhibit a first-order martensitic transition (MT) in the vicinity of a second-order ferromagnetic-to-paramagnetic phase transition. Contrasted with a sharp, complete and thermoelastic MT in MSR, a partial, sluggish and nonthermoelastic MT occurs in annealed Ni 55 Fe 20 Al 25 alloy that possesses a much higher degree of atomic order. However, the annealed samples have stronger local magnetocrystalline anisotropy and higher Curie temperature (T C ) than MSR. Negative magnetoresistance, ∆ρ || / ρ, is two times larger in MSR than in the annealed case. ∆ρ || / ρ vs. H isotherms in MSR change curvature from concaveupwards to concave-downwards as the temperature is raised through T C whereas concavedownward curvature persists over the entire temperature range in the annealed counterpart.

Dynamic elastic properties and magnetic susceptibility across the austenite-martensite transformation in site-disordered ferromagnetic Ni–Fe–Al alloy

“…PACS Numbers: 62.40.+i, 72.55.+s, 75.40.Cx, 81.30.Kf Thermoelastic martensitic transformation from face-centered-cubic (fcc) austenite (hightemperature) phase to tetragonal martensite (low-temperature) phase in a new ternary ferromagnetic alloy system Ni-Fe-Al ("prepared" in different states of site disorder) has been recently reported 1 based on the results of a detailed neutron diffraction (ND), electrical resistivity, ) (T ρ…”