The effects of P and Re complex modification with different P and Re addition on the microstructure and mechanical properties of hypereutectic Al-20Si alloy have been investigated.The results show that P and Re complex modification can greatly refine the primary Si phase and eutectic Si phase

in which the size of primary Si phase is decreased and spheroidized

and the eutectic Si phase is converted from needle-like into particles.The optimized microstructure and mechanical properties can be observed with 0.08%P and 0.6%Re addition

in which the tensile strength at room and high temperatures is 306 MPa and 187 MPa

respectively

improved by 20% and 34% than that of un-modified alloys

and the elongations at room and high temperatures reach up to 0.48% and 1.58% respectively

improved by 40% and 88%respectively than those of un-modified ones.