Abstract
A combination process of the rapid solidification and the chemical leaching processing was applied to get metastable nanocrystalline materials of Co-Cu. The structure and magnetic properties of the as-solidified and the leached alloys were examined by the X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, transmission electron microscopy and magnetization measurements. The rapid solidification of various Al75CoxCu25-x (x=0-25at%) alloys was quite effective to get supersaturated powders. The structure of the powders by the leaching of aluminum atoms in sodium hydroxide solution was drastically changed to a fcc phase with broad X-ray diffraction patterns. Very fine particles were observed by the transmission electron microscopy. The larger particles more than 40nm were facetted. The heat treatment of the leached specimen at 1073K for 1800s changed the structure to two fcc with sharp X-ray diffraction patterns corresponding to those of Co and Cu. The saturated magnetization of the leached specimen increased by the heating and its magnitude was larger in the specimens prepared by this combination process than that of the binary mechanically alloyed or rapidly solidified specimens.
