The structure evolution of Ti-46at % Al alloy during mechanical alloying

Blended elemental powder with the nominal composition (at%) Ti(54)Al(46) was mechanically alloyed in a planetary ball milling system for up to 100h. The structure evolution in the powder was characterized by scanning electron microscope, micro-hardness analysis, X-ray diffraction and differential thermal analysis techniques. It was found that with increased milling time, powders became equiaxed and the distribution of particle size became narrow; the micro-hardness of powders increased and the distribution of micro-hardness of different particles became uniform. After 60h milling, elemental powders were progressively transformed into nanocrystalline Ti (Al) supersaturated solid solution, then into amorphous phase which was attributed to the fine grain size, and the grain size condition for formation of amorphous phase in this system is less than or equal to 15nm.