Sr变质对蛇形通道浇注Al-22Si-Cu合金组织的影响

采用纯铜蛇形通道浇注和Sr变质的复合工艺,对Al-22Si-Cu过共晶合金组织与性能进行研究。结果表明,蛇形通道工艺可将初生Si晶粒尺寸从90μm细化至28.03μm。随着Sr含量增加,初生Si的析出温度降低,合金的孪晶密度和初生Si尺寸均先增大后减小,当Sr含量为0.09%时达到最大值;共晶Si由长针状转变为纤维状;Sr含量为0.12%时,合金的抗拉强度达到212.32MPa。

Effects of Combined Process Using Serpentine Pouring Channel and Sr-modifier on the Microstructure of Al-22Si-Cu Hypereutectic Al-Si Alloy

In order to compound refinement of primary Si and modification of eutectic Si,the Al-22 Si-Cu alloy was investigated which was prepared by the combined process using a water-cooled copper serpentine pouring channel(SPC)and Sr-modifier.The results indicate that the grain size of primary Si is refined from 90μm to 28.03μm by the serpentine pouring channel process.With increasing in the Sr content,the precipitation temperature of primary silicon is decreased,and the twin density and grain size of primary Si are both increased firstly and then decreased,which reach the maximum value with the addition of 0.09%Sr.The eutectic Si morphology is modified from acicular to fibrous.The tensile strength of the Al-22 Si-Cu alloy with the addition of 0.12%Sr reaches 212.32 MPa.