中文摘要：

本研究采用金相显微镜、X射线衍射（XRD）、能谱分析及扫描电镜（SEM）等技术，对重力铸造制坯后热挤压成Al-Sr中间合金线材与挤压铸造制坯后热挤压成Al-Sr中间合金线材中A14Sr相的微观形貌、晶粒尺寸和断口形貌进行了对比分析。试验结果表明，挤压铸造制坯后热挤压成形Al-Sr中间合金线材中的A14Sr相呈细小颗粒状，分布均匀，等效圆半径约为25．4m，合金伸长率达到24．74％。塑性的提高使得中间合金线材易于加工成卷。同时，挤压铸造制坯后热挤压成形的Al—Sr中间合金线材具有较短的变质孕育期，变质效果良好。

英文摘要：

The microstructure including the morphology, size of Al4Sr phase in Al-Sr master alloy, formed by hot extrusion after gravity casting and squeeze casting, as well as the fracture morphology of the Al-Sr master alloys had been analyzed and examined by using of optical microscopy, X-Ray Diffraction （XRD）, energy spectrum analysis and scanning electron microscope device. The results show that the Al4Sr intermetallic phase with the mean radius of 25.4 μm was fine and evenly distributed in the aluminium matrix in the Al-Sr master alloys prepared by squeeze casting process. The ductility was improved remarkably and an elongation of 24.74% was obtained after the squeeze casting process of Al-Sr alloy, and then the alloy with better modification performance could be obtained because of the lower induction period of modification.