Structure–magnetic properties correlation in mechanically alloyed nanocrystalline Fe–Co–Ni–(Mg–Si)x alloy powders

Abstract

Fe–Co–Ni–(Mg–Si)x (x = 0.0, 0.1, 0.2) alloys were synthesized via mechanical alloying in a high energy planetary ball mill for 25 h. Structural characterization of as-milled powders was characterized utilizing X-ray diffraction (XRD) technique, scanning electron microscope and transmission electron microscope (TEM). Vibrating sample magnetometer was used to evaluate the magnetic properties of as-milled powders at room temperature. XRD analysis of equiatomic Fe–Co–Ni alloy confirmed the presence of BCC as the major phase and FCC as the minor phase. However, a single phase FCC solid solution was formed in case of Fe–Co–Ni–(Mg–Si)x (x = 0.1 and 0.2) alloys. The crystallite size reduced substantially from 19.26 nm for Fe–Co–Ni–(Mg–Si)0.0 to 10.56 nm for Fe–Co–Ni–(Mg–Si)0.2. The evolution of powder morphology is discussed extensively as a function of mechanical alloying time and content of (Mg–Si)x (x = 0.0,0.1,0.2). High resolution-TEM confirmed the existence of nanostructured crystallite size and selected area diffraction pattern were in good agreement with the XRD results in the case of all the powder samples. The magnetic behavior study of mechanically alloyed powders confirmed a high saturation magnetization of 266.67 emu/g for Fe–Co–Ni–(Mg–Si)0.2 alloy and an appreciably low coercivity of 16.52 Oe for Fe–Co–Ni–(Mg–Si)0.1 alloy.