Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2003. / Includes bibliographical references (leaves 77-80). / This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections. / The {111}<112̄> shear stress-displacement behavior for face-centered cubic (fcc) metals, aluminum and copper, is calculated using empirical potentials proposed by Mishin and by Ercolessi, based on the embedded atom method (EAM), and compared with published ab initio calculations. In copper close agreement is observed in the results given by the Mishin potential for both the ideal shear strength and local atomic relaxation during shear, although the extent of plastic deformation before failure is over-predicted. In aluminum, both the Mishin and Ercolessi potentials are used, with only the former able to capture the majority of the behavior exhibited in first principle calculations. Both potentials are shown to have difficulties modeling the effects of directional bonding. Calculations of the multiplane generalized stacking fault energy in both materials reveal that aluminum has a longer range of atomic interaction than copper. Using molecular dynamics and static energy calculations, deformation twins are shown to form by homogeneous nucleation, slip and subsequent coalescence of partial dislocations in both copper and aluminum. The minimum energy path for formation of a two-layer microtwin, and the energy barriers to its further growth are analyzed for the two metals. The mechanism observed is interpreted with reference to existing work on the nucleation of microtwins in body-centered cubic metals. / by Robert D. Boyer. / S.M.
| Identifer | oai:union.ndltd.org:MIT/oai:dspace.mit.edu:1721.1/17035 |
| Date | January 2003 |
| Creators | Boyer, Robert D. (Robert Damian), 1978- |
| Contributors | Sidney Yap., Massachusetts Institute of Technology. Dept. of Materials Science and Engineering., Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. |
| Publisher | Massachusetts Institute of Technology |
| Source Sets | M.I.T. Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | 80 leaves, 1113038 bytes, 1454882 bytes, application/pdf, application/pdf, application/pdf |
| Rights | M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission., http://dspace.mit.edu/handle/1721.1/7582 |
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