Preparation of Al2O3-Mo3Si /Mo5Si3 nanocomposite powders by mechanochemical reduction method

Al2O3-Mo3Si /Mo5Si3 nanocomposite powders were synthesized by mechanochemical reduction method with MoO3, Si and Al powders as raw materials. The solid-state reaction process and synthesized composite powders were investigated by XRD, laser particles size analytic instrument, TEM, SEM and DTA-TG method. Experimental results indicated that Al2O3-Mo3Si /Mo5Si3 composite powders were obtained by milling of MoO3-Si-Al powders for 5h by the mechanical induced self-propagating reactions. The grain sizes of Mo3Si, Mo5Si3 and Al2O3 were 27.5nm, 23.3nm and 31.8nm respectively after milling of 20h. The composite powders possessed nano-crystalline structure and the average particle size was 3.988μm, with spherical shapes and uniform distribution after 20h. DTA analysis results showed that the first reaction was a thermite reaction of MoO3 and Al in the milling process, followed by a series of reactions to form Mo3Si and Mo5Si3 in the Mo-Si system.