Enhanced strength and ductility at room and elevated temperatures of Al-Cu alloy matrix composites reinforced with bimodal-sized TiCp compared with monomodal-sized TiCp

The bimodal-sized (micron+nano) TiCp/Al-Cu composites were successfully fabricated by adding the in situ micron-sized and nano-sized TiCp-Al master alloys into the molten Al-Cu alloy. The composites reinforced with bimodal-sized TiCp exhibited finer α-Al grains and smaller θ′ precipitates, and possessed enhanced room- and high-temperature strength and relatively high ductility compared with the Al-Cu matrix alloy and their counterparts reinforced with monomodal-sized TiCp. The improved tensile properties may be attributed to the more significant precipitation strengthening due to the smaller θ′ precipitates, grain refinement and strengthening effects of the nano-sized and micron-sized TiCp.