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The process of mechanical alloying in the 33Al-45Cu-22Fe (at.%) powder mixture subjected to high-energy ball milling was studied. Due to complexity of the alloy formation in this system, several methods – X-ray diffraction phase analysis, Differential Dissolution, thermal analysis and Transmission and Scanning Electron Microscopy – were combined to obtain the detailed information on the structure and composition of the mechanical alloying products. Possible formation mechanisms of these phases during mechanical alloying are discussed. No crystalline phase containing Fe and Cu, Al has been found in the products of mechanical alloying of the 33Al-45Cu-22Fe mixture. The formation of Cu-Al phases followed the sequence of Al 2 Cu → Al 4 Cu 9 → Cu(Al) solid solution. When only those phases that were detected by the XRD analysis were taken into account, the mass balance of Al and Fe in the products of mechanical alloying was not satisfied. The Differential Dissolution and high-resolution Transmission Electron Microscopy data suggest the formation of non-stoichiometric X-ray amorphous phases containing all three elements. Reasons for the retardation of the solid-state interaction between aluminum and copper in the ternary powder mixture are discussed. [ABSTRACT FROM AUTHOR]

We report the phase and microstructure evolution of the Cu–13 wt.% Al mixture during treatment in a high-energy planetary ball mill with a particular focus on the early stages of mechanical alloying. Several characterization techniques, including X-ray diffraction phase analysis, nuclear magnetic resonance spectroscopy, differential dissolution, thermal analysis, and electron microscopy/elemental analysis, have been combined to study the evolution of the phase composition of the mechanically alloyed powders and describe the microstructure of the multi-phase products of mechanical alloying at different length scales. The following reaction sequence has been confirmed: Cu + Al → CuAl 2 (+Сu) → Cu 9 Al 4 + (Cu) → Cu(Al). The phase evolution was accompanied by the microstructure changes, the layered structure of the powder agglomerates disappearing with milling time. This scheme is further complicated by the processes of copper oxidation, reduction of copper oxides by metallic aluminum, and by variation of the stoichiometry of Cu(Al) solid solutions with milling time. Substantial amounts of X-ray amorphous phases were detected as well. Differential dissolution technique has revealed that a high content of aluminum in the Cu(Al) solid solution-based powders is due to the presence of Al-rich phases distributed between the Cu(Al) crystallites. [ABSTRACT FROM AUTHOR]