2012 Fiscal Year Final Research Report
Rejuvenation of metallic glasses by disordering and relaxation controlling
| Project/Area Number |
23656418
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Multi-year Fund |
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| Research Field |
Structural/Functional materials
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| Research Institution | Tohoku University |
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Principal Investigator |
SAIDA Junji 東北大学, 学際科学国際高等研究センター, 准教授 (20359540)
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| Co-Investigator(Kenkyū-buntansha) |
WAKEDA Masato 大阪大学, 大学院・基礎工学研究科, 助教 (00550203)
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| Project Period (FY) |
2011 – 2012
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| Keywords | 金属ガラス / 構造緩和 / 不規則性 / 機械的性質 / 構造制御 / 相変態 / シミュレー ション |
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| Research Abstract |
Relaxation of glassy alloys is generally regarded as one of the important phenomena originating from the intrinsic random structure. Due to a strong correlation with structure, transformation, mechanical and magnetic properties of metallic glasses, we have to control the relaxation state carefully for industrial use. Relaxation state depends on a cooling rate just above glass transition temperature, Tg. We have investigated the recovery of the less relaxation state by low temperature annealing just above Tg and various cooling conditions in several glassy alloys by experimental and molecular dynamics (MD) simulation studies. The enthalpy of relaxation increases by such low temperature annealing at higher cooling rates with a significant mechanical softening. The MD simulation clearly indicates that the glassy alloys can be rejuvenated in the case of higher cooling rates than the initial one (i.e., cooling rate in the initial preparation of glass) by annealing over Tg. Such rejuvenation is saturated in the temperature range over 150 K above Tg. The result is consistent with the experimental one using Cu mold casting. The present study on recovering and controlling relaxation state provides useful information on the application of metallic glasses.
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