2020 Fiscal Year Research-status Report
Development of precipitation-hardenable magnesium sheet alloys with strong and rapid age-hardening response
| Project/Area Number |
20K15067
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| Research Institution | National Institute of Advanced Industrial Science and Technology |
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Principal Investigator |
Bian Mingzhe 国立研究開発法人産業技術総合研究所, 材料・化学領域, 研究員 (30848320)
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| Project Period (FY) |
2020-04-01 – 2022-03-31
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| Keywords | Magnesium alloys / Age-hardening response / Precipitate / Atomic radius / Mixing enthalpy |
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| Outline of Annual Research Achievements |
In this year, a new precipitation-hardenable Mg sheet alloy based on the magnesium-silver-calcium (Mg-Ag-Ca) system has been developed. A newly developed Mg-12Ag-0.1Ca (wt.%) alloy sheet shows an average tensile yield strength of 147 MPa in a T4-treated condition. Subsequent artificial aging for 336 h (T6) increases the tensile yield strength to 181 MPa, which is associated with the formation of AgMg4 phase. By optimizing the chemical composition, the age-hardening kinetics is significantly accelerated. A newly developed Mg-1.5Ag-2Ca (wt.%) alloy sheet can reach a peak hardness condition within an hour, which is substantially shorter than the time to reach the peak hardness condition of the concentrated Mg-12Ag-0.1Ca alloy sheet.
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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
This project aims to elucidate whether mixing enthalpy values and atomic size of the solute elements are the important factors to form precipitates in Mg alloys. In this year, we demonstrated that a combination of undersized Ag (1.44 angstrom) and oversized Ca (1.97 angstrom) could lead to the formation of Ag and/or Ca enriched precipitates and thus successfully developed a new type of precipitation-hardenable Mg-Ag-Ca alloy.
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| Strategy for Future Research Activity |
In the remaining time of the project, we will evaluate age-hardening response of Mg-In-Gd and Mg-Sn-Li alloys. The Mg-In-Gd alloys are a combination of oversized elements (In=1.63 angstrom and Gd=1.80 angstrom), while Mg-Sn-Li alloys are a combination of undersized elements (Sn=1.41 angstrom and Li=1.52 angstrom). The cast ingots will be extruded, homogenized and thermomechanically processed under different rolling conditions to obtain 1 mm thick plates. Characterization of age-hardening response will start soon after the sheets are produced. A comprehensive characterization by scanning electron microscope, electron backscatter diffraction , transmission electron microscopy of samples prepared under different processing conditions will be done.
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| Causes of Carryover |
Since the virtual conferences were held, travel expenses were not occurred.
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