Journal of Alloys and Compounds 481 (2009) 320–325 Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: www.elsevier.com/locate/jallcom Preparation of Al 2 O 3 –TiC nanocomposite by mechano-chemical reduction of TiO 2 with aluminum and graphite M. Zakeri ∗ , M.R. Rahimipour, S.K. Sadrnezhad, R. Yazdani-rad Ceramics Department, Materials and Energy Research Center, P.O. Box 31787/316, Karaj, Iran article info Article history: Received 24 January 2009 Received in revised form 23 February 2009 Accepted 24 February 2009 Available online 13 March 2009 Keywords: Nanostructured materials Mechano-chemical processing abstract Al 2 O 3 –TiC (AT) nanocomposite was synthesized by mechanical alloying (MA) of TiO 2 , Al and graphite powder mixture. Effect of the milling time, starting composition and heat treatment temperatures were investigated. X-ray diffraction (XRD) was used to characterize the milled and annealed powders. The morphological and microstructural evolutions were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Results show that the formation of TiC initiates after 20h and completes after 35 h of milling. Residual Al in the 35 h milled powder was removed by lessening its content in the initial mixture to 20 wt.%. Annealing of the 80 h milled sample at 800 ◦ C led to the obtaining maximum micro-hardness of 16.25 GPa. Mean crystallite size of 12 nm was estimated for 35 h milled sample with 28 wt.% Al. TEM and SEM images confirmed the nanocrystalline structure with very good distribution and homogeneity of TiC and Al 2 O 3 , respectively. © 2009 Elsevier B.V. All rights reserved. 1. Introduction Ceramic–matrix composites have attracted the attention of researchers for many years because of their potential for structural applications. Al 2 O 3 reinforced with nano-sized particles such as TiC, WC, SiC, NbC, etc. represent a new class of materials with improved mechanical properties, hardness and wear resistance when com- pared to monolithic ceramics [1–7]. AT composites are widely used as substrate of magnetic heads and cutting tools due to their attrac- tive mechanical properties and good electrical conductivity [8]. At present commercially available micro-sized AT composites are pre- pared by pressure-less sintering or hot pressing the direct mixtures of Al 2 O 3 and TiC powders [9,10] during which severe grain coars- ening and generation of metal oxides at the interface always take place due to relatively long holding time at high temperature [11]. Because of weak binding forces at the interface, grains are often pulled out when the AT composites are machined. This is espe- cially detrimental if the crystallite size is large, which results in low product yield. Furthermore, the problem becomes more seri- ous with the ongoing miniaturization of magnetic disk drive sliders. Thus it is a current trend to prepare fine-grained AT composites for future development of hard disk drive. Mechanical alloying (MA) [12] has been considered as a powerful and practical process for fabrication of several advanced materi- als with unique properties [13], in particular, for those materials ∗ Corresponding author. Tel.: +98 261 6204131; fax: +98 261 2611888. E-mail address: M zakeri@merc.ac.ir (M. Zakeri). that are difficult to be obtained by the traditional way of liquid metallurgy. High thermal stable metallic glasses and amorphous alloys [14], nanocrystalline and nanocomposite materials [15,16], and refractory hard materials, including metal nitrides and silicides [17,18], carbides [19], hydrides [20] are examples of the advanced engineering materials that are prepared at room temperature, using the MA method. There have been some attempts to produce AT composite by mechanical alloying. Jiang and coworkers investigated the in situ synthesis of Al 2 O 3 –TiC nanocomposite from a mixture of Ti, graphite and Al 2 O 3 (nano) powders by ball milling [21]. Razavi et al. used elemental powders of Ti, Al and graphite. TiC–Al 2 O 3 was formed during the annealing of milled powder at oxygen atmo- sphere with some impurities [22]. The present study proposes an attractive route for preparation of AT nanocomposite powders at room temperature, by ball milling a mixture of TiO 2 , Al and graphite powders. For the first time, these inexpensive raw materials (TiO 2 , Al and graphite) were used for preparation of AT composite. One aim of this work thus is to offer an inexpensive technique for fabrication of technologically important materials. 2. Experimental details Mechanical alloying was performed in a planetary ball mill at nominal room temperature with a vial rotation speed (cup speed) of 500 rpm. Pure Al (Fluka Co., 99.9 wt.%, <200 m), graphite (MERCK, 99.9 wt.%, <50 m) and TiO2 (MERCK, 99.9 wt.%, <50 m) powders were mixed to give the desired AT composite on the basis of following reaction: TiO2 + 4 3 Al + C = 2 3 Al2O3 (53 wt.%) + TiC (47 wt.%) (1) 0925-8388/$ – see front matter © 2009 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2009.02.122