a comparison between the effect of cr and w addition on formation kinetic of nanostructure tial(γ) alloy by mechanical alloying route

in this research, mechanical alloying was used to produce ti-50al, ti-45al-5cr and ti-45al-5w (at%) alloys. the effect of ternary addition (cr and w) on microstructure and production efficiency of tial alloy were investigated. alloying was performed in a planetary mill and the milling time varying from 5 to 70h. the structural evaluation in these powders was done by x-ray diffraction (xrd) technique and scanning electron microscopy (sem) during mechanical alloying and after annealing at 1100°c in vacuum oven. the results showed only a complete amorphous phase after 50h of milling of ti-50al powder mixture, but with 5at% addition of cr, the cr (ti, al) solid solution within the amorphous matrix were identified after 70h milling and with 5at% addition of w, the w lattice was remained with amorphous phase. the time required for solid solution or amorphous phase formation was longer in cr and w containing powders. after annealing of mechanically alloyed ti-50al, the γ-phase with high purity and nanostructured size was produced and for sample with cr addition, the tial(γ) with amount of ti3al(a2) were formed and for sample with w addition, the duplex phase (γ+a2) with a minor amount of w, were formed.