Fe 3 Al intermetallic compound has several advantages such as high hardness, high melting point, relatively low density and high temperature oxidation resistance. The main problems of this compound are embrittlement at room temperature, low creep resistance at high temperatures and low strength at T 600 o C. These problems can be overcome by adding third alloying element like Ti, decreasing crystallite size and uniform distribution of fine stable particles in the matrix. The aim of this research was to synthesis (Fe,Ti) 3 Al-Al 2 O 3 nanocomposite by mechanical alloying (MA). The formation of (Fe,Ti) 3 Al intermetallic compound by MA was first considered and evaluated by thermodynamic analysis of Fe-Al-Ti ternary system using semi-empirical miedema’s model. In next step (Fe,Ti) 3 Al-Al 2 O 3 nanocomposite was synthesized by utilizing the displacement reactions of Al-TiO 2 and Al-Fe 2 O 3 during mechanical alloying. X-ray diffractometry (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA) and microhardness measurements were used to characterize powder particles after different milling times. MA of Fe-Al-Ti powder mixture with molar ratio of Fe 50 Al 25 Ti 25 led to the formation of Fe(Al,Ti) solid solution and which transformed to nanocrystalline (Fe,Ti) 3 Al intermetallic compound with DO 3 structure after 100h of milling time. Heat treatment of this compound at 550 o C for 1h led to the formation of ordered structure. Thermodynamic analysis of Fe-Al-Ti ternary system indicated that substitution of Ti for Fe in Fe 3 Al compound reduces the Gi free energy and therefore Fe 3 Al compound is more stable compound compared to (Fe,Ti) 3 Al compound. MA of Fe-Al-TiO 2 powder mixture formed (Fe,Ti) 3 Al-Al 2 O 3 nanocomposite by gradual reaction of TiO 2 and Al. It was found that this reaction occurs in 2 stages: reduction of TiO 2 by Al and then formation of (Fe,Ti) 3 Al compound. (Fe,Ti) 3 Al-Al 2 O 3 nanocomposite was obtained after 5h mechanical alloying of Al-Ti-Fe 2 O 3 powder mixture. Fe 2 O 3 -Al reaction occured with a combustion mode in this system. Also MA of Fe-Al-Ti-Fe 2 O 3 powder mixture led to the formation of (Fe,Ti) 3 Al-Al 2 O 3 nanocomposite by gradual reduction of Fe 2 O 3 by Al. The products of this reaction were disordered (Fe,Ti) 3 Al intermetallic compound and amorphous Al 2 O 3 . Heat treatment of
