Synthesis and characterization of nanocrystalline and amorphous (Al₄Cu₉)_94.5Cr_5.5 γ-brass alloy by rapid solidification and mechanical milling

Abstract

An as-cast ingot was used for rapid solidification and high energy ball milling in order to synthesize amorphous and/or nanocrystalline (Al₄Cu₉)_94.5Cr_5.5 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.