2021 Fiscal Year Research-status Report
Establishment of deformation law of metallic glasses based on local atomic level analysis
| Project/Area Number |
21K20418
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| Research Institution | Japan Atomic Energy Agency |
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Principal Investigator |
Ivan Lobzenko 国立研究開発法人日本原子力研究開発機構, 原子力科学研究部門 原子力科学研究所 原子力基礎工学研究センター, 博士研究員 (30802293)
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| Project Period (FY) |
2021-08-30 – 2023-03-31
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| Keywords | Metallic glass / Atomic stress / LCAO / Shear softening |
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| Outline of Annual Research Achievements |
New approach of atomic stress calculation based on linear combination of atomic orbitals was applied to CuZr soft metallic glass (MG). It is shown that under shear strain Cu subsystem provides stress drop, while atomic stress on Zr atoms mostly increase. Partial densities of states (PDOS) were examined to unveil mechanisms of shear softening in the CuZr MG. PDOS is attributed to each atom and therefore can be compared with atomic stress change in the relaxation process. PDOS change shows that d-orbital of Zr atoms undergo biggest changes. That highlights importance of Zr directional bonding character in the shear softening. Also with analysis of Mulliken charges it was shown that with increase in strain more electrons flow from Zr d-orbital to some other orbitals.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Some key features of Zr-based metallic glasses deformation mechanisms are already discovered. Namely, importance of d-orbital for atomic stress drop was shown. Importance of Zr as alloying element was also discovered in the modeling of medium-entropy alloys using both first principles and classical molecular dynamics simulations. In particular, softening of bulk modulus and elastic constants was found in MoNbTa alloy if Mo is substituted with Zr.
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| Strategy for Future Research Activity |
Using the gathered data an unsupervised machine learning will be applied to uncover the correlations between calculated atomic features and shear stress drop. Those features include charge transfer, chemical short-range order and electronic partial densities of states change.
The analysis already proved valuable for Cu50%Zr50% metallic glass will be applied to CuZr metallic glasses with other stoichiometric ratios. Also glasses with different stiffness will be studied by varying cooling rates in computer simulations. Results will led to formulation of universal mechanisms of deformation in Zr-based bulk metallic glasses.
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| Causes of Carryover |
Due to the COVID situation, conferences was held on-line. Therefore transportation expenses decreased.
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