In this study, MoSi 2 -TiB 2 nanocomposites with 10 and 20 wt.% TiB 2 were synthesized and characterized by mechanical alloying via three routes. In the first route, elemental powders of molybdenum, silicon, titanium and boron were milled for 60 h. In the second route, MoSi 2 was synthesized first from Mo and Si by 30 h milling and Ti, B elemental powders were added and the mixture was milled for 60 h. In the third route, MoSi 2 was made by 30 h milling of Mo and Si and commercial TiB 2 was added and milling was continued for 30 h. Heat treatment at 1000?C for 60 min was carried out on the powders that were produced by three routes. The effect of mechanical alloying on grain size and lattice strain was investigated by williamson-hall method. The morphology and microstructure of produced powders were studied by SEM and EDS. The results indicated that the nanocomposite powders synthesized by the first route with 20 wt.% TiB 2 and heat treatment, contained on Mo 5 Si 3 and MoB phases. The results showed that second route required more reaction time than the first route. The results of XRD patterns showed that the produced MoSi 2 by three routes was ? mixture and ?. Heat treatment of samples resulted in ?-MoSi 2 to ?-MoSi 2 phase change, increase in the grain size and decrease in the micro-strain. The lattice constant of MoSi 2 was calculated by Nelson–Riley method. The mechanical properties of samples were determined by hardness test. The results indicated that increasing the milling time, increases the hardness of samples due to plastic deformation and work hardening. It was also found that by adding TiB 2 to MoSi 2 hardness was increased considerably. Agglomeration process was carried out on the powders to be used in the thermal spray process. The spherical degree and particle size distribution of agglomerating was evaluated using clemex software. The results showed that the nanocomposite powder produced by the first route had high quality for use in the thermal spray process due to high hardness and suitable spherical degree of particles. Key words : Nanocomposite, Mechanical alloying, agglomeration, MoSi 2 , TiB 2
