Iron aluminides have received considerable attention as a structural material because of their advantageous properties, in particular, high specific strength, relatively high wear resistance and hardness, high melting point, high oxidation and corrosion resistance. However, industrial application of these alloys has been limited due to their brittleness at room temperature and their poor creep resistance above 600 ° C. Several approaches were attempted to improve their major drawbacks such as reducing the grain size to nanometric range, dispersion strengthening and addition of alloying elements such as Cr. Taking all these factors into account, the synthesis of particulate reinforced FeAl(Cr) intermetallic compound composite with nanostructured matrix can be interesting. The reinforcement particles can be either directly added to the matrix (ex-situ technique) or formed by an in-situ displacement reaction. One possible route for in-situ introducing hard particles in the matrix of composites is the mechanochemical processing in which high-energy milling promotes the displacement reaction in a mixture of reactive powders. In this study, fabrication and formation mechanism of alumina reinforced (Fe,Cr) 3 Al matrix nanocomposite via mechanochemical processing have been investigated. In first stage, formation mechanism of (Fe,Cr) 3 Al intermetallic compound by ball milling of Fe-Al-Cr powder mixture has been studied. In second stage (Fe,Cr) 3 Al-Al 2 O 3 nanocomposite were fabricated using two routes; ball milling of Fe-Al-Cr 2 O 3 powder mixture and ball milling of Fe 2 O 3 -Al-Cr powder mixture. The structural evaluation of powders was studied by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and differential thermal analysis (DTA) and microhardness measurements. Results showed that in early stages of ball milling of Fe 50 Al 25 Cr 25 powder mixture, a composite lamellar structure of Fe, Cr and Al is formed in which the dissolution of Al and Cr atoms in Fe lattice takes place. The resulting solid solution finally leads to the formation of nanocrystalline disordered (Fe,Cr) 3 Al phase. It was found that during milling of Fe-Al-Cr 2 O 3 system, Al gradually reacts with Cr 2 O 3 leading to the formation of metallic Cr and Al 2 O 3 phases. The reduced Cr and remaining Al concurrently diffuse into the Fe lattice and as a result a Fe(Al,Cr) solid solution develops. This structure transformed to (Fe,Cr) 3 Al intermetallic compound at longer milling times. In Fe 2 O 3 -Al-Cr system, a combustion
