Abstract
In this study, the mixture of Ti, Al, and B elemental powders with nominal composition Ti-25at%Al-B was fabricated by mechanically alloying technique. The structural and compositional evolutions during MA process were investigated by XRD and SEM techniques. Results showed that the crystallite size of Ti and Al decreased with increasing milling time. The mechanically alloyed Ti-Al powder was predominantly nanocrystalline with traces of the remnant amorphous phase. The dissolution of Al and B elements in Ti matrix was obtained for milling time lower than 4 h, forming h.c.p. Ti(Al, B) solid solution. The lattice parameter ratio c/a and the unit cell volume of h.c.p. Ti(Al, B) were found to decrease with increasing milling time, indicating that the shrinkage of Ti lattice was caused by diffusion of Al and B atoms into Ti. However, for milling time higher than 4 h, we can observe both phases Ti(Al, B) and fcc phase. An amorphous structure is achieved after 12 h of milling. This amorphous powders get crystallized on further milling time (18 h). The observation by scanning electron microscope shows a phenomenon of fracturing followed by compaction of the powder particles. For milling time 20 h, we can observe only the fcc phase.