On The Plastic Behavior of Nanocrystalline Aluminum

• Main Authors: Delphic Chen, 陳志慶
• Other Authors: Jui-Chao Kuo
• Format: Others
• Language: zh-TW
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/95752251832807484413

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 94 === 　　Mechanical Properties of nano materials are strongly influenced by measurement techniques. The application of nanoindenter is used to investigate the local mechanical properties of the material. It is still an open question that these properties of the local could represent these of bulk material. In order to investigate the deformation behavior of nanocrystalline aluminum, in this study two different approaches were used, namely Taylor model simulation and tensile test. Four different sized grains were used for the tensile test, Single Crystal, 2-3mm sized oligo grain, 0.1mm sized oligo grain, and 20-30nm sized nanocrystalline aluminum. 　　The optical microstrain measurement were used to observe the microstrain distribution on the sample surface. As for the simulation, Taylor model is applied in this study to show the texture evolution. 　　The results indicate that the grain size of electrodeposited film is about 20~30 nm and it is texture free. The maximum elongation before necking decreases with decreasing grain size. The optical microstrain distributions show that the single crystal exhibits strong anisotropic deformation properties, and the 2-3mm sized oligo grain also shows this phenomenon in the local region. Therefore, the grain size and the specimen size could affect the mechanic properties. After tensile deformation simulation, β-fiber texture is predicted by using Taylor Model. However, under tensile test there is no texture observed in nanocrystalline aluminum. This suggests that dislocation slip is not the deformation mechanism of nanocrystalline aluminum.