Synthesis and characterization of nanocrystalline and amorphous (Al4Cu9)94.5Cr5.5 γ-brass alloy by rapid solidification and mechanical milling

An as-cast ingot was used for rapid solidification and high energy ball milling in order to synthesize amorphous and/or nanocrystalline (Al4Cu9)94.5Cr5.5 γ-brass alloy. Microstructure of the milled product has been characterized by X-ray diffraction, differential scanning calorimetry, high-resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. Rapid solidification by melt spinning produces nanocrystalline aggregate of size ∼40 nm and mechanical milling of the alloy up to 50 h yields a composite microstructure comprising of amorphous and nanocrystalline phases, with crystallite size in the range of 15–25 nm. No other metastable phases have been identified. Attempts have been made to understand the possibility of formation of amorphous phase through mechanical milling using semi-empirical model of Miedema.