Correlation between the grain-shape and magnetic properties in nanocrystalline iron

Abstract Correlation between magnetic properties and time evolution of size (d) and shape of grains of pure nanocrystalline iron produced by ball-milling were investigated by Barkhausen-noise and lowfield magnetization measurements. Strong texture and elongated grain structure were developed after some hours milling time, and the thickness of elongated grains was in accordance with the grain size obtained from X-ray line broadening. After prolonged milling, disruption of the elongated grains and development of equiaxed grain structure was observed. There was a maximum in the Barkhausen-noise when the above lamellar structure was the most typical. It is shown that the coercive force (Hc) is not sensitive to the formation of the grain structure, but the course of the Hc(d) curve strongly depends on the initial and preparation conditions. In accordance with our previous results, the saturation magnetization was independent of the grain size.