Soft magnetic properties of nanocrystalline Ni3Fe and Fe75Al12.5Ge12.5

Magnetization curves were measured on Ni3Fe and Fe75Al12.5Ge12.5, nanocryst als of different grain sizes. These materials were prepared by high-energy ball milling, followed by annealing at various temperatures. The alloy comp ositions were chosen because they have low magnetostriction in bulk form, i mplying that strain in the samples should have little effect on their magne tic properties. The M-H magnetization curves were used to obtain the coerci vity, the maximum permeability, and the saturation magnetization. Differenc es in these magnetic properties were related to changes in grain size and i nternal RMS strain. In spite of the low hulk magnetostriction of these mate rials, the internal stress controlled the coercivity. The changes in permea bility, however, were not as expected from the trend in grain size. We sugg est that the powder morphology, plays an important role in determining the soft magnetic properties of these nanocrystalline alloys. (C) 2000 Acta Met allurgica Inc.