Abstract: The elementsFe, Ni and Ti were added in the form of AlFeNiTi master alloy (atomic ratio 1∶1∶1∶1), which were fused by vacuum arc melting furnace, andthe influence of the addition amounts of the master alloy (0.5%,1.0%,1.5%,2.0%,2.5%, mass fraction) on Si phase, α-Al and mechanical properties of Al-20Si alloy were studied. The results showed that when the addition concentration of AlFeNiTi master alloy is 2.0%, the morphology of primary Si is transferred from coarse irregular block and five folds to fine and regular block and its average size is reduced from 91 μmto 40 μm by 56.1%. The eutectic Si is modified from coarse needle/flake-like morphology to the edge passivation and fine granular shape. Moreover, the primary α-Al is refined from coarse dendrites to fine rosette-like structure and the secondary arm dendrites spacing is significantly decreased, and the ultimate tensile strength(UTS)is increased by 41.1% from 129 MPa to 182 MPa, and the elongation(EL) isenhanced by 78.7% from 0.8% to 1.43%.

Key words: Al-20Si alloy, AlFeNiTi master alloy, microstructure, mechanical properties