Exploiting superior tensile properties of a novel network-structure AlA206 matrix composite by hybridizing micron-sized Al3Ti with Al2O3 nano particulates

In this study, semi-solid stir casting and ball milling processes are combined into an integrated composite fabrication process. Two different architectures were utilized to incorporate reinforcing particle into semi-solid alloy i.e., (i) ball milling of K2TiF6 and aluminum powder for 5 h and subsequently with nano-alumina particles (Al2O3np) for 1 h and (ii) ball milling of K2TiF6, Al2O3np and aluminum powder for 2 h. Accordingly, the milled powders were incorporated into molten AlA206 alloy using a non-contact ultrasonic vibration method. The effect of milling procedure on microstructural evolution and tensile properties were then explored. Two different microstructures were characterized including well-distributed Al2O3np and Al3Ti particles (Al3Tip) and a network-structure containing Al3Tip+Al2O3np. This unique architecture of network-structure brought about increment in tensile properties compared to well-distributed reinforcement particles, ascribed to the strewing of Al3Tip+Al2O3np around matrix grain boundaries, act as a three-dimension skeletal structure with high local volume fraction of Al3Tip+Al2O3np.