Mechanism investigation of NiTi-20wt.%Al2O3 nanocomposite formation by mechanical alloying

Intermetallic compounds have been the focus of significant research and development efforts during the last 15 years. The major obstacles for the use of intermetallic compounds are their low ductility and toughness at ambient temperature and, in some cases, insufficient strength and creep resistance at high temperatures. It has been recognized for some years that intermetallic matrix composites may be the likely form for ultimate structural applications [1]. NiTi intermetallic is well known for its unique physical and mechanical properties, such as good ductility, good vibration damping properties, corrosion resistance and also thermal shape memory effects that can be utilized for a number of applications [2]. On the other hand Al2O3 has a combination of desirable properties, such as low density, high specific strength and high modulus [3] which can provide stiff ceramic inclusions introduced into an intermetallic matrix, such as NiTi, enhancing the mechanical properties and thermal stability of the composite. Several techniques have been developed to produce a wide array of intermetallic matrix composites. Among them, mechanical alloying (MA) technique is well known for synthesis of compounds and nanocomposites using the mechanochemical reactions [4]. In this study NiTi/Al2O3 nanocomposite was synthesized by MA and mechanochemical reaction between NiO and Al. The formation mechanism of nanocomposite was investigated