In the current investigation fabrication and characterization of Ti6Al4V-Al 2 O 3 nanocomposite by mechanical alloying has been studied. In this regard, the Ti6Al4V matrix was fabricated from elemental powders and Ti6Al4V residual scraps. Also the nanocomposite was synthesized by mechanochemical reaction of TiO 2 , Ti, Al, V powder mixture and mechanical milling of Ti6Al4V scraps together with Al 2 O 3 nanoparticles. Phase transformation, structural changes and morphological evaluations of powder particles were evaluated by means of X-ray diffraction (XRD), Scanning electron microscope (SEM) and Thermal analysis (DTA). The results revealed that in the early stages of mechanical alloying of Ti-Al-V powder mixture Ti(Al)-hcp solid solution is produced and further milling results in formation of Ti(Al, V) solid solution and amorphous phase. Heat treatment of the amorphous and Ti(Al, V) phase eventually led to the fabrication of a nanostructured Ti6Al4V alloy. Subjecting the as milled powder to elevated temperature for longer time periods results in crystallization of Ti6Al4V(?) phase and excessive grain growth. Moreover in order to compare the properties of final products, Ti6Al4V scraps were mechanically milled. It was observed that the micro hardness value of nanostructured Ti6Al4V powder produced from elemental powders was significantly higher than that of mechanically milled scraps. In situ Ti6Al4V-Al 2 O 3 nanocomposite was fabricated by mechanical alloying. The nanocomposite was produced gradually during milling and heat treating of TiO 2 , Ti, Al and V powder mixture. The crystallization of the amorphous phase and formation of nanostructure Al 2 O 3 phase occurred during milling. Mechanical milling of Ti6Al4V scraps with Al 2 O 3 nanoparticles led to production of ex situ Ti6Al4V-Al 2 O 3 nanocomposite powder exhibited good thermal stability and high microhardness. The physical and mechanical properties of the in situ and ex situ Ti6Al4V-Al 2 O 3 nanocomposites during milling and after heat treatment were compared. Keywords Ti6Al4V matrix nanocomposite, Al 2 O 3 , Mechanical alloying
