The main objective of this study is to investigate the microstructural evolution during mechanical milling of prealloyed (Ti_(52)Al_(48))_(100-x)B_x powders and also to investigate the effects of B contents and heat treatment on the microstructure of mechanically milled TiAl alloys. Microstructure of binary Ti_(52)Al_(48) Powders consists of grains of hexagonal phase whose structure is very close to Ti₂Al. (Ti_(52)Al_(48))_(95)B_5 powders contain TiB₂ in addition to matrix grains of hexagonal phase. The grain sizes in the as-milled powders of both alloys are nanocrystalline. The mechanically alloyed powders were consolidated by vacuum hot pressing (VHP) at 1000℃ for 2 hours, resulting in a material which is fully dense. Microstructure of consolidated binary alloy consists of γ-TiAl phase with dispersions of Ti₂AlN and A1₂O₃ phases located along the grain boundaries. Binary alloy shows a significant coarsening in grain and dispersoid sizes. On the other hand, microstructure of B containing alloy consists of γ-TiAl grains with fine dispersions of TiB₂ within the grains and shows the minimal coarsening during annealing.