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 ...