2002 Fiscal Year Final Research Report Summary
Study of microscopic mechanism of plastic deformation in inorganic materials with non-periodic structure
| Project/Area Number |
12450261
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (B)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Physical properties of metals
|
|---|
| Research Institution | Tokyo University of Science |
|---|
Principal Investigator |
TAKEUCHI Shin Tokyo University of Science, Dept. Mater. Sci. & Technology, Professor, 基礎工学部, 教授 (60013512)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TAMURA Ryuji Tokyo University of Science, Dept. Mater. Sci. & Technology, Research Professor, 基礎工学部, 助手 (50307708)
EDAGAWA Keiichi The university of Tokyo Inst. Industrial Sci., Associate Professor, 生産技術研究所, 助教授 (20223654)
|
|---|
| Project Period (FY) |
2000 – 2002
|
| Keywords | non-periodic structure / quasicrystal / amorphous metal / flow stress / computer simulation / dislocation / Peierls mechanism |
|---|
| Research Abstract |
It has been clarified that quasicrystals and metallic glasses, both having non-translational symmetry structure, can undergo plastic deformation by slip process. The purpose of the research is to elucidate the microscopic slip deformation mechanisms in these materials of non-translational symmetry, by means of experiments over a wide deformation conditions and of computer simulations
(1) As a result of high temperature deformation experiments on various quasicrysmtals, the following facts have been clarified:(a) any quasicrystal can be plastically deformed only above 0.75Tm (Tm: melting point), and the yield stress decreases rapidly with increasing temperature, (b) quasicrystals commonly exhibit pronounced work-softening, and (c) the work-softening is concluded to occur as a result of decreasing activation enthalpy. Based on the computer simulation of dislocations in model quasicrystals, the dislocation glide in a quasicrystal is exerted by a resistance due to a phason wall production s
… More
uperimposed by that due to a quasiperiodic Peierls potential, and its rate is controlled by kink-pair formation at high temperatures. The deformation behavior is well explained by the model where on the phason-free quasicrystal the dislocation mobility is governed by kink-pair formation at large Peierls potentials, while as phason- defect density increases with plastic deformation it is governed by that at small Peierls potentials
(2) Deformation experiments of bulk metallic glasses over a wide temperature range have been shown that their yield stresses are almost temperature independent down to near zero Kelvin. In order to elucidate what kink of dislocation glide governs the slip in metallic glasses, computer simulation studies have been performed. A realistic model binary metallic glass has been constructed by means of the inverse Monte Carlo method and by use of interatomic potentials for a Ni-Nb alloy. It has been classified that dislocation is stable only when its Burgers vector is larger than about 3A. The slip deformation model for the dislocation of the minimum Burgers vector is tentatively assumed, but the final deformation model has not been established yet, since the simulation for the dislocation glide has not been completed Less
|
