Formation and chemical leaching of non-equilibrium Al 0.6(Co 75Cu 25) 0.4 alloy powders by rod milling

Abstract

We report upon the formation of nanoscale crystalline Al 0.6(Co 75Cu 25) 0.4 alloy powders and leached non-equilibrium specimens, produced by employing a combination of rod milling and chemical leaching. X-ray diffractometry (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and vibrating sample magnetometry (VSM) were used to characterize the as-milled and leached specimens. After 400 h of milling, bcc type peaks of the intermetallic compound AlCo were present in the XRD pattern. Leaching of the Al from the as-milled powders did not induce any significant change in the diffraction pattern. After annealing the leached specimen at 600 °C for 1 h, the nanoscale crystalline phase was transformed into the Co and fcc Cu phases, and this was accompanied by a change in the magnetic properties. Magnetization decreased gently upon heating from room temperature to 155.4 °C, then increased suddenly with rising temperatures up to 350.0 °C, as the Co and Cu atoms were rearranged, and finally decreased gently as heating continued to 850 °C. On cooling the specimen from 850 °C, the magnetization increased gently. The Curie temperature was about 570.7 °C for the as-milled powders.