不同凝固条件下Al4Sr相的形貌特征演变

摘要 以Al-20Sr合金为研究对象，采用浇铸和吸铸两种方式制备了中间合金，利用扫描电镜系统考察了不同凝固条件下初生Al4Sr相的形貌特征演变.结果表明:850℃浇铸时，Al4Sr相呈规则且完整的块状形貌，950℃浇铸时Al4Sr相呈长条状，具有明显的择优晶体学生长特征(择优晶体学生长方向<100>)；升温至850℃吸铸时， 试样中心和边部的Al4Sr相均呈较规则且完整的块状形貌，升温至900，950℃，降温至900℃吸铸时，试样中心Al4Sr相主要呈细长条竹节状，边部呈短条或椭圆状，降温至850，800℃吸铸时中心呈粗大和细小条状两种形貌，降温至750℃吸铸时为粗大的条状.凝固条件对Al4Sr相的形貌有重要影响.
Abstract：Al-20 Sr intermediate alloys were prepared by both mold and suction castings. The morphological evolution of the primary Al4Sr phase under different solidification conditions was investigated by SEM. The results showed that in the mold cast specimens the primary Al4Sr phases are regular and complete block-like shape at 850℃ and are strip-like form with obvious preferential crystallographic growth character at 950℃. In the suction cast specimens， the primary Al4Sr phases are regular and complete block-like shape when the temperature is increased to 850℃， fine bamboo-like shapes in the central and short strip-like and elliptical forms in the peripheral regions when the temperatures are increased to 900℃ and 950℃ and then decreased to 900℃， coarse and fine stripe-like shapes when the temperatures are decreased to 850℃ and 800℃， and coarse stripe-like forms when the temperature is decreased to 750℃， respectively. In summary， solidification conditions have important influence on the morphologies of Al4Sr phase.