A review on the synthesis of in situ aluminum based composites by thermal, mechanical and mechanical–thermal activation of chemical reactions B. S. B. Reddy Æ Karabi Das Æ Siddhartha Das Received: 1 December 2006 / Accepted: 8 May 2007 / Published online: 17 August 2007 Ó Springer Science+Business Media, LLC 2007 Abstract The aim of the present paper is to review the recent progress in the synthesis of in situ particle reinforced aluminum composites using thermal, mechanical and combined mechanical-thermal activation of aluminother- mic reduction reactions. The combination of combustion synthesis (CS) and mechanosynthesis (MS) is the most recent development in the processing of advanced materi- als like micro and nano aluminum based composites. The combined mechanical thermal synthesis (MTS) has wid- ened the possibilities for both CS and MS. MTS holds great potential for commercial viability and offers exciting processing route for the synthesis of advanced materials. Enhanced reaction kinetics and extended concentration limits in MTS are demonstrated by illustrating the synthesis of aluminum based nanocomposite involving Al–CeO 2 . Introduction The possibility of taking the advantage of particular properties of the constituent materials to meet specific demands is the most important motivation for the devel- opment of composites. Metal matrix composites (MMCs) are the materials where rigid ceramic and/or intermetallic reinforcements are embedded in a ductile metal or alloy matrix. MMCs combine best properties of its constituent materials i.e. metallic properties (ductility and toughness) with ceramic or intermetallic characteristics (high strength and modulus). It is now well recognized that metal matrix composites (MMCs) have a high potential for advanced structural applications. Aluminum is the most popular matrix for the metal matrix composites (MMCs). The Al alloys are quite attractive due to their low density, their capability to be strengthened by precipitation, their good corrosion resis- tance, their high thermal and electrical conductivity, and their high damping capacity. Aluminum matrix composites (AMCs) have been widely studied since the 1920s and in the 1980s, transportation industries began to develop dis- continuously reinforced AMCs. They are very attractive for their isotropic mechanical properties (higher than their unreinforced alloys) and their low costs. AMCs are finding more and more applications and their usage is increasing continuously over the past 25 years. This is due to the development and better understanding of different processing techniques resulting in reproducible microstructures and properties. Also the developments in the processing of nano to micron sized reinforcements attracted material scientists towards the processing of advanced AMCs. The discontinuously reinforced AMCs, specifically the particulate-reinforced AMCs, are of par- ticular interest due to their isotropic nature and ease of fabrication [1–3]. Traditionally, the particulate-reinforced AMCs are pro- duced by processing techniques such as powder metallurgy, preform infiltration, spray deposition and conventional melting casting route. In all the above techniques, prior to the composite fabrication, the reinforcement (usually in particulate form) is prepared and combined with the matrix material (either in molten or powder form). Thus, traditional AMCs can be viewed as ex situ AMCs. Ex situ particulate- reinforced AMCs are suffered with uneven distribution of reinforcement and non-wetting of the reinforcement and B. S. B. Reddy  K. Das (&)  S. Das Department of Metallurgical and Materials Engineering, Indian Institute of Technology, Kharagpur 721302, India e-mail: karabi@metal.iitkgp.ernet.in 123 J Mater Sci (2007) 42:9366–9378 DOI 10.1007/s10853-007-1827-z