Microstructure Evolution and Mechanical Properties of a SMATed Mg Alloy under In Situ SEM Tensile Testing

作     者：Xiaowei Liu Yong Liu Bin Jin Yang Lu Jian Lu 

作者机构：1 CentreforAdvanced Structural Materials(CASM)Department of Mechanical and Biomedical EngineeringCity University ofHong KongKowloonHong KongChina Key Laboratory of Near Net Forming of Jiangxi ProvinceNanchang UniversityNanchang 330031China Shenzhen Research InstituteCity University of HongKongShenzhen 518057China 

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

年 卷 期：2017年第33卷第3期

页      面：224-230页

核心收录：

学科分类：08[工学] 080502[工学-材料学] 0805[工学-材料科学与工程（可授工学、理学学位）] 

基　　金：supported by the National Key Basic Research Program (Grant No. 2012CB932203) the National Natural Science Foundation of China (Grant No. 51301147) the funding support from City University of Hong Kong (Grant Nos. 9610288 and 9680108) the funding support from the National Natural Science Foundation of China (Grant No. 51464234) 

主　　题：Surface mechanical attrition treatment(SMAT) Mg alloy Mechanical property In situ SEM Microstructure characterization 

摘      要：Surface mechanical attrition treatment（SMAT） has been recently applied to bulk polycrystalline magnesium（Mg） alloys with gradient grain size distribution from the impact surface to inside matrix, hence effectively improving the alloys＇ mechanical performances. However, in-depth understanding of their mechanical property enhancement and grain size-dependent fracture mechanism remains unclear. Here,we demonstrated the use of in situ micro-tensile testing inside a high resolution scanning electron microscope（SEM） to characterize the microstructure evolution, in real time, of SMATed Mg alloy AZ31 samples with different grain sizes of ~10 μm（＇coarse-grain sample＇） and ~5 μm（＇fine-grain sample＇）, respectively, and compared the results with those of a raw Mg alloy AZ31. The quantitative tensile tests with in situ SEM imaging clearly showed that fracture of ‘fine-grain sample＇ was dominated by intergranular cracks,while both trans-granular and intergranular cracks led to the final failure of the ‘coarse-grain samples＇.It is expected that this in situ SEM characterization technique, coupled with quantitative tensile testing method, could be applicable for studying other grain-refined metals/alloys, allowing to optimize their mechanical performances by controlling the grain sizes and their gradient distribution.