Structural and Magnetic Properties of Mechanically Alloyed Fe-Co Powders

The Fe-Co alloys are well known as ferromagnetic materials exhibiting high values of saturation magnetization, Curie temperature and magnetostriction. In powder form they are commonly used in the magnetic recording media. In this paper the structural and magnetic properties of a series of Fe-Co alloy powders prepared by mechanical alloying are presented. The Fe-Co powders (with 30, 45, 50 and 60 wt. % of Co) were prepared by mechanical alloying of high purity powder elements mixture in a planetary ball mill (Retsch PM 4000). The milling of all samples was performed in argon atmosphere with the ball-to-powder weight ratio of 15:1 and the speed of 180 rpm for 30 hours. The X-ray diffraction investigations show, that the alloying of fcc-Co into bcc-alpha-Fe took place during the milling, leading to the formation of the bcc-FeCo solid solution. It was found, that the lattice parameter (with values from 0.2861 nm to 0.2866 nm) of the investigated mechanically alloyed Fe-Co samples is larger for samples containing higher concentration of Co. The process of mechanical alloying was confirmed by Mössbauer spectrometry. The structure and powder size were observed by both TEM and SEM investigations. The coercivity (with values from 2.4 kA m-1 to 3.9 kA m-1) of the powders (measured by a Förster Koerzimat at room temperature) containing higher Co content exhibit larger values.JRC.F.4-Nuclear design safet