Development of Nanostructured Intermetallic Compounds and Composites inNi-Ti-Nb Ternary System by Mechanical Alloying In this investigation, the synthesis of Ni 50 Ti (50-x) Nb x (x=5, 10, 25), nanostructured alloys, Ni 50 Ti 25 Nb 25 -Al 2 O 3 nanostructured composites with 5 and 10 weight percent Al 2 O 3 , Ni 50 Ti 25 Nb 25 , Ni 50 Ti 40 Nb 10 and Ni 50 Ti 45 Nb 5 stoichiometric nanostructured composites were studied by mechanical alloying. The milling process was carried out at room temperature in a planetary ball mill under Ar atmosphere. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermal analysis and microhardness measurements were used to characterize the milled and heat-treated powders. The milled powder after 40 h was annealed for 1 h at 900?C under argon atmosphere to investigate the phase transitions occurring during annealing. The hardness of powders was also determined by microhardness measurements using aVickers indentor at a load of 50 g and dwell time of 5 s. Formation kinetics was also analyzed using Johnson–Mehl–Avrami (JMA) equation for Ni 50 Ti 25 Nb 25 alloy. Thermodynamic analysis of the process was also carried out using Miedema model. Kinetic analysis in Ni 50 Ti 25 Nb 25 showed that reaction of solid solution formation is diffusion controlled. The results showed that mechanical alloying of Ni 50 Ti 25 Nb 25 , Ni 50 Ti 40 Nb 10 and Ni 50 Ti 45 Nb 5 powder mixtures led to the formation of an amorphous phase.At the early stages of MANi and Nb atoms were dissolved in Ti latticein Ni 50 Ti 25 Nb 25 alloy, Nb and Ti atoms dissolved in Ni lattice in Ni 50 Ti 40 Nb 10 and Ni 50 Ti 45 Nb 5 alloys.By further increasing the milling time nanocrystalline layers formed. This structure caused enhancement of diffusion process in low temperatures and amorphous phase formation from kinetics viewpoint. Heat treatment of amorphous phases gave rise to the formation of NiTi, Ni 3 Ti and NiNb phases in the first alloy, Ni 3 Ti, NiTi 2 and NiNb phases in the second alloy, NiTi, Ni 3 Ti and NiTi 2 phases in the third alloy. Thermodynamic investigation showed that the first phase formed in all of Ni 50 Ti (50-x) Nb x alloys was solid solution. Mechanical alloying products in three alloys were in agreement with the results obtained from miedema model. NiO, Ti, Nb and Al powders were used as