EFFECT OF MECHANICAL MILLING ON THE MICROSTRUCTURE AND MORPHOLOGY OF AA 2024-MoSi2 NANOCOMPOSITE POWDERS

The present study consists of two parts. In the first part, nano-sized MoSi2 powder was produced successfully from commercially available MoSi2 by a mechanical milling process carried out for 100 h. In the second part of this research, mechanical alloying was employed to synthesis AA 2024- MoSi2 nanocomposites. Effects of MoSi2 reinforcement and mechanical milling on the structure, morphology and iron contamination of the produced materials were investigated using X-raydiffraction, electron microscopy and atomic absorption spectrometry. Results revealed that themorphology of the aluminum alloy changes continuously during milling from spherical to platelike, irregular and finally equiaxed. The presence of MoSi2 reinforcement accelerates the milling process and results in smaller average particle size. Williamson-Hall method determined that crystallite size of the aluminum in the composite powder is smaller than that of the unreinforced alloy at the same milling time and this size reaches to 45 nm after 16 h milling time. The Fe contamination content was higher for the nanocomposite in comparison with unreinforced alloy because of the wearing role of MoSi2 hard particles.

کلیدواژه ها:

Mechanical milling ، Microstructure ، Nanocomposite ، Aluminum alloy