The Role of Sr and TiB on Mechanical Properties of Aluminium 6061 Composites Produced through Stir Casting Route

Abstract

Aluminium 6061 composites have been succesfully produced by stirr casting method. The process involved melting aluminium at 800°C and mixed with AlSr, TiB and Mg to produce master alloy of matrix phase, then degassing to remove all of gas entrapped in molten aluminium by argon. There are two types of particles reinforced added into aluminium to produce aluminium composite such as SiC and Al2O3. The particles reinforced addition for both SiC and Al2O3 are started from 2vf-% to 10vf-% to obtain the optimum compostion which have good mechanial propperties. The addition of 10wt-% Mg is to promote wetting between matrix and reinforced while the addition of AlSr and TiB are to improve mechanical properties by modifying the eutectic structure as well as grain refinement of the matrix phases. The two composites are compaired both mechanical properties and microstructure analysis. The mechanical properties of Al/SiC composites such as tensile strength, elongation, and hardness have a maximum value at addition of 10 Vf-% SiC with the value up to 230 MPa, 6.5%, and 62 HRB respectively. While for Al/Al2O3 composites have the highest tensile strength and elongation at 6 Vf-% Al2O3 with the value of 224 MPa and 7% respectively, but the highest hardness is obtained at addition of 10 Vf-% Al2O3 reaches to 55 HRB. The percentages of porosity were increased for both composites along with the increase of particles reinforced. The microstrutures for both composites are similar since they have the same matrix and Sr clearly changed primary Mg2Si become finer chinese scripts, while TiB as grain refiner worked efficiently for higher reinforced particles addition because the grain size reduced for both composites.