MECHANICAL PROPERTIES OF A356-CNT CAST NANO COMPOSITE PRODUCED BY A SPECIAL COMPOCASTING ROUTE

A356 aluminum alloys reinforced with carbon nano-tubes (CNTs) were produced by stir casting and compocasting routes and their microstructural characteristics and mechanical properties in ambient and high temperature were examined. In order to alleviate the problems associated with poor wettability, agglomeration and gravity segregation of CNTs in the melt, CNTs were introduced into the melts by injection of CNT deposited aluminum particles instead of raw CNTs. The slurries were subsequently cast at temperatures corresponding to fully liquid as well as 0.15 and 0.30 solid fractions. The results showed that addition of CNTs to A356 matrix could significantly increase the mechanical properties. Yield strength and ultimate tensile strength of the composite samples were significantly improved compared with the corresponding monolithic samples. While the monolithic sample kept about 60% of its strength at 300 degrees C, the semi-solid composite samples kept more than 90% of their strength at this temperature.