Al-Cu合金共晶凝固组织形貌及其影响因素

Solidification Morphology of Al-Cu Alloy and Its Influencing Factors

利用光学显微镜、扫描电镜等仪器研究了Al-Cu合金中-αAl及-θAl2Cu相的生长行为,成分及冷却速度对共晶组织形貌的影响。结果发现,在过共晶组织中,初生-θAl2Cu相形貌大部分有明显的拐角,呈现小平面生长特性。在α-Al与-θAl2Cu相共晶耦合生长时,-θAl2Cu择优生长特征削弱,与-αAl耦合生长呈现非小平面-非小平面生长。在亚共晶组织中,出现了θ-Al2Cu包裹着初生-αAl相的晕圈组织。随着冷却速度的加大,共晶组织细化,初生-αAl相枝晶发达,初生-θAl2Cu由大块板条状向短矩形转变。

The morphologies of primary crystal phase α-Al and θ-Al2Cu in Al-Cu alloys with various composition and cooling velocity were observed by optical microscope（OM） and scanning electron microscope（SEM）.The results show that the primary crystal phase Al2Cu in the hypereutectic structure have obvious corners,that indicates they have the faceted growth properties.But when it grows with α-Al in the eutectic structures,the preferred orientation of Al2Cu is weaken,and the non-faceted to non-faceted coupled growing is showed.The halo microstructures of primary α-Al phase surrounded by θ-Al2Cu were found in the hypoeutectic structures.With the increasing of cooling rate,the eutectic structure becomes finer and finer,and developed primary α-Al phase can be observed.The big plate primary θ-Al2Cu phase becomes short rectangle.