Deformation Behavior and High-pressure Torsion and Subsequent Annealing S. LEE 1 and K. Tsuchiya 1 1 Research Center for Structural Materials, National Institute for Materials Science (NIMS) Our research group has reported the fabrication of an equiatomic CuCoNi medium-entropy alloy and phase separation behavior after severe plastic deformation by high-pressure torsion (HPT) and subsequent annealing. After the annealing, the dual-FCC phase with Cu-rich and Co-Ni formed due to the large miscibility gap of Cu-Co. In this study, deformation behavior and microstructure evolution of CoCuNi processed by HPT and subsequent annealing were investigated. 54PP22--2211 PP22--2222 An equiatomic CoCuNi MEA was produced by highThe as-homogenized specimen showed a tensile strength of 400 MPa with 10% elongation. After the HPT, both the strength and ductility increased to 1.5GPa and 15%, respectively. With increasing annealing temperature and time, the ductility improved with the expense of the strength. The tensile strength decreased to 520MPa with 37% elongation after the annealing at 800 ℃ for 100 hrs. In this case, the extended Luders band was observed until the true strain of 0.15. The grain refinement of the Co-Ni phase was dominantly observed in the Luders band. Development of a new Age-hardenable MTemperature Formability and Corrosion-resistance K. Kikuchi 1, T. Nakata 1, Z. Li 2, Y. 1 Department of Mechanical Engineering2 Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science (NIMS) Mg-Zn-Ca-Al-Mn (ZXAM) alloy is a new type of Mg sheet alloy with large room temperature (RT) formability and strength. A high content of Mn is the key to forming a high density of Al-Mn precipitates, which results in grain refinement and thus high strength. However, the Al-Mn precipitates promote galvanic corrosion with the Mg matrix, deteriorating the corrosion resistance. Therefore, it is required to develop low Mn-containing ZXAM alloys without the loss of strength. In this work, we focused on age-hardening, and effects of Zn and Ca contents on the RT formability, tensile and corrosion properties in low Mn-containing ZXAM alloys were investigated. The Zn content has a small influence on the mechanical properties, whereas the Ca content is crucial to improving the RT formability and strength. The age-hardening response was improved by the Ca addition of ≥ 0.5%, and the yield strength is increased by ~30 MPa after aging without the large loss of the corrosion-resistance. However, the 1%Ca addition of formed coarse particles and thus decrease the formability. As a result, an optimum composition was Mg-2Zn-0.5Ca-0.2Al-0.2Mn. The Index Erichsen value of the alloy reaches 8.7 mm after solution treatment, and artificial aging results in a high yield strength of 213 MPa along the rolling direction. Combined with a low corrosion rate is ~3 mm/y in NaCl solution, this alloy exhibits superior properties compared with recently designed wrought Mg alloys. Poster Presentation ｜NIMS Award Symposium 2023 Microstructure of Dual-phase CoCuNi Alloy Processed by Miyashita 1 T. Sasaki 2 and S. Kamado 1 , Nagaoka University of Technology agnesium Alloy Sheet with Excellent Room P2 ｜ Characterization-frequency vacuum melting the processed into a cylindrical shape by high-temperature rolling and swaging. The HPT process was applied on disk samples with a thickness of 0.85 mm at room temperature with a pressure of 5 GPa and a rotation speed of 1 rpm to 10 rotations. After the HPT, the sample was annealed at 400 ℃ for 100 hrs, and at 800 ℃ for 1, 10, and 100 hrs. To investigate the microstructure and mechanical properties, XRD, SEM-EBSD, EDS, and tensile tests were conducted. ℃ and 600
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