A Study on Deformation Mechanisms and the Formation of Shear Bands of Different Crystalline States during High Compression by Molecular Dynamics Simulation

• Main Authors: Chang-Jun Shen, 沈昌峻
• Other Authors: Yuan-Ching Lin
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/2m6967

碩士 === 國立臺灣科技大學 === 機械工程系 === 106 === The study analyzes the deformation mechansims and the shear bands initiation of the FCC crystal copper and the BCC crystal iron bulks of different arrangements <100> and <110> with two kinds of high compressive strain rates. Furthermore, the amorphous materials of silver / gold / copper / palladium / nickel and silver / gold / iron / palladium / nickel are also simulated with two different temperatures, 5K and 295K. The results show that no matter in what kinds of crystalline states, the higher strain rate leads to higher yielding stress and strain. However, different deformation mechansims are induced in different crystal structures. In FCC, the deformation mechansims of the <100> specimens are the partial dislocations but the <110> specimens are not only caused by partial dislocaions but also the twins. In BCC, both <100> and <110> specimens are due to the cross slips of screw dislocations. In amorphous, the deformation is due to the regional atomic displacement which is induced by the free volume. In addition, in amorphous, the new free volume formed in room temperature specimens and the silver / gold / iron / palladium / nickel specimens occur obviously; however, less free volume formed in low temperature specimens.