Effects of P-Re Modification on Microstructure and Mechanical Properties of Hypereutectic Al-20Si Alloy

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.