Chemical Leaching of Non-Equilibrium Al(Fe-Co) Powder Produced by Rod Milling

Abstract

We report on the formation and chemical leaching of non-equilibrium Al0.6(Fe75Co25) alloy produced by rod milling. X-ray diffractometry, transmission electron microscopy, differential scanning calorimetry, scanning electron microscopy, and vibrating sample magnetometry were used to characterize the as-milled and leached specimens. After 400 h, only the Al0.4Fe0.6 peak of the body-centered cubic type was present in the XRD pattern. The entire rod milling process could be divided into three different stages of milling: agglomeration, disintegration, and homogenization. The saturation magnetization, Ms decreased with increased milling time, the Ms of the powders before milling was about 113.8 emu/g, the Ms after milling for 400 h was about 11.55 emu/g. Leaching of the Al in KOH of the Al at room temperature from the as-milled powders did not induce any significant change in the diffraction pattern. After the leached specimen had been annealed at 600℃ for 1 hour, the nanoscale crystalline phases were transformed into the bcc Fe, cubic Co, and CoFe2O4 phases. On cooling the specimen from 850℃, the degree of magnetization increased slightly, then increased sharply at approximately 364.8℃, indicating that the bcc Al0.4Fe0.6 phase had been transformed to the Fe and Co phases.