Preparation of Mo(Si,Al)2-ZrO2 nanocomposite powders by mechanical alloying

Phase transformations and the final formation of Mo(Si,AI)(2)-ZrO2 nanocomposite during high-energy ball milling of a series of Mo-Si-Al-ZrO2 powders were investigated. Mechanical alloying led to phase transformations from the initial Mo-Si-Al powders mixture to Mo-ss (2 h) --> C40 Mo(Si,Al)(2) (4,8 h) --> Mo-ss (12 h) phases. The phase transformations studied by XRD are discussed considering the alloying and second phase effects. Finally, the Mo,, matrix reinforced with ZrO2 particles nanocomposite structure was studied by means of TEM. The Mo-ss matrix phase formed was revealed to be strongly inhomogeneous even after 12 h of mechanical alloying and Mo-, Si- and Al-enriched regions were observed. The ZrO2 nanostructured phase, evenly distributed in the Mo,, matrix. had grain size of about 5-20 nm. (C) 2004 Elsevier Ltd. All rights reserved.