Morphologies of Al_4Sr Intermetallic Phase and Its Modification Property upon A356 Alloys

作     者：Chengwei Liao Jianchun Chun Yang Li Rui Tu Chunxu Pan 

作者机构：School of Physics and Technology and Center for Electron MicroscopyWuhan UniversityWuhan 430072China Hunan Jinlianxing Specially Materials Technology Co.LtdYueyang 414005China 

出 版 物：《Journal of Materials Science & Technology》 (材料科学技术（英文版）)

年 卷 期：2012年第28卷第6期

页      面：524-530页

核心收录：

学科分类：08[工学] 080401[工学-精密仪器及机械] 0804[工学-仪器科学与技术] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0803[工学-光学工程] 

基　　金：supported by the National Basic Research Program of China ("973 Program",2009CB939705) the Hunan Jinlianxing Metallurgical Materials Technology Co.Ltd,China 

主　　题：Intermetallics Modification Hot extrusion Heat treatment Microstructure 

摘      要：In general, the modification performance of AI-Sr master alloys is primarily dependent upon the morphologies and sizes of the AI4Sr intermetallic phase. In this paper, the crystal structure, morphologies, sizes, hardness and elastic modulus of AI4Sr in AI-Sr master alloys prepared from variant processes were studied by means of optical metallurgical microscope, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and nanoindentation system. The results revealed that the microstructures and modification performance of the AI4Sr phase were related to the preparation processes. That is to say, when a ＂direct reaction-hot extrusion＂ process was used, the AI4Sr phase exhibited a homogeneous distribution in the AI matrix with small size and roundish shapes, which ensured the AI-Sr master alloy wire advantages involving high recovery, good reproducibility, no delitescence of modification, no corrosion on equipments, and good workability. However, in the case of the traditional ＂direct reaction＂ process, the AI4Sr phase was in large size with shapes of rectangular stripe and plates, which limited the Sr content increasing due to the brittleness of the AI-Sr alloy. It was also found that the morphology and size of the AI4Sr phases changed during heat treatment at high temperature up to 600℃.