Optimization of modification process for hypereutectic Al-20 Si alloy with Er was analyzed.And the orthogonal experiment with 3factors and 4levels which included modification temperature

modification time and Er content was designed to optimize modification parameters.Then

effects of single factor（content

temperature and time）on microstructure and compressive strength of hypereutectic Al-Si alloy were analyzed.The results show that with the increase of Er content

modification temperature and time

the size of primary silicon in alloy is decreased to the stable

and the eutectic silicon shape is converted from needle to short rod and then to needle too

meanwhile

the compression strength is increased to the peak value and then decreased.With modification treatment at 730 ℃ for 25 min and0.8% rare earth Er addition

the primary silicon size is approximately 50μm

and the eutectic silicon exhibits short rod

meanwhile

the compressive strength reaches 492.6 MPa.