中文摘要：

研究了Er对Al-20Si合金的变质工艺的优化,设计了Er含量、变质温度和变质时间3因素4水平的正交试验,确定了最佳工艺参数,并分析了单因素对Al-20Si合金微观组织和抗压强度的影响。结果表明,随着变质温度、变质时间及Er含量的增加,初晶Si尺寸由大变小,后趋于不变,共晶Si由针状转变为短棒状再变为针状,抗压强度先增大后减小。当变质温度为730℃、变质时间为25min,Er含量为0.8%时,Al-20Si合金初晶Si尺寸最小,约为50μm,共晶Si为短棒状,抗压强度达到最大值492.6 MPa。

英文摘要：

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.