the structural and mechanical properties of al-2.5%wt. b4c met-al matrix nano-composite fabricated by the mechanical alloying

in this study, aluminum (al) matrix reinforced with micro-particles (30 µm) and nano-particles (50 nm) boron carbide (b4c) were used to prepare al-2.5%wt., b4c nano-composite and micro-composite, respectively, using mechanical alloying method. the mixed powders were mechanically milled at 5, 10, 15 and 20 hrs. the xrd results indicated that the crystallite sizes of both the micro-composite and nano-composite matrix decreased with increasing milling time, showing 55 nm and 40 nm, respectively. mechanical testing results showed an increase in the flexural strength from 98 to 164 and 115 to 180 mpa, and an increase in the hardness from 60 to 118 and 75 to 130 hv for micro-composite and nano-composite, respectively. the results indicate that the strength and hardness of the nano-composite are higher than those of the micro-composite due to the presence of the fine particles.