Evaluation of crystallite size and micro-strain during mechanical milling process of composite material AA6005A+ 10% nano-TiC

Abstract

Powder metallurgy process (by high-energy mechanical milling) was used to obtain a nanostructured aluminum matrix composite. Powders of the AA6005A alloy (particle size <63 μm) was utilized as matrix, and 10% by weight of nano-sized TiC particles (20-30 nm) as reinforcement. Composite powder was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Microstructural changes produced during the milling process, such as modification of crystallite size and micro-strain of matrix lattice were determined using the three Williamson-Hall (W-H) analysis models: UDM (Uniform Deformation Model), USDM (Uniform Stress Deformation Model) and UDEDM (Uniform Deformation Energy Density Model). The results show that crystallite size decreases and micro-strain increases sharply in the first few hours of milling and then both parameters remain stable until 10 hours. The three W-H models present a coefficient of determination R2 close to the unit indicating that are suitable to determine crystallite size and lattice micro-strain of nanostructured composite obtained.

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