京都大学 · 工学
鄭浩陳教授の研究室では、中高エントロピー合金やレアアース含有高エントロピー合金を対象に、原子レベルの歪みと変形メカニズムの制御を根幹とした新規高強度・高延性材料の創出をめざしています。特に、固体ソリューション硬化パラメーターや積層欠険エネルギーの制御を通じて、低温でも優れた機械的特性を示す材料設計の新アプローチを開発しています。微小試料を用いたマイクロピルラーキャパシティ測定や、結晶方位依存の塑性変形挙動の解明が、材料の破壊挙動の理解に貢献しています。
Figures are computed from collected data and may differ slightly.
A new route to achieve high strength and high ductility compositions in the Cr-Co-Ni medium entropy alloys (MEAs) is proposed, by controlling the solid solution hardening parameter (Mean Square Atomic Displacement, MSAD) and twinning propensity parameter (Stacking Fault Energy, SFE), respectively. The MSAD is calculated to increase with the increase in the Cr content and with the increase in the Ni/Co ratio at high Cr concentrations, while the SFE is calculated to decrease with the increase in t
The temperature-dependent yield strengths of [1¯23]-oriented single crystals of four quinary non-equiatomic Cr-Mn-Fe-Co-Ni high-entropy alloys (HEAs) were investigated at temperatures of 10-1173 K. They exhibit similar trends with a rapid decrease of the critical resolved shear stress (CRSS) from 10 K to 300 K, followed by a much slower rate of decrease with increasing temperature and a plateau above 873 K. The HEAs with the highest and lowest Cr contents exhibit the highest and lowest yield str
The plastic deformation behavior of a B2-ordered TiCrMo-15Al refractory high-entropy alloy (RHEA) has been investigated as a function of crystal orientation and specimen size by micropillar compression at room temperature, in an attempt to understand the origin for the brittle behavior of the B2 compound based on the identified operative slip systems and dislocation structures. Plastic flow is observed even at room temperature for all orientations investigated with the slip direction always bein
The plastic deformation behavior of single crystals of Fe3Ge with the L12 structure has been investigated at room temperature as a function of crystal orientation by micropillar compression tests. In addition to slip on (010), slip on (111) is observed to occur in Fe3Ge for the first time. The CRSS (critical resolved shear stress) for (111)[101¯] slip, estimated by extrapolating the size-dependent strength variation to the ‘bulk’ size, is ~240 MPa, which is almost 6 times that (~40 MPa) for (010
The plastic deformation behavior of single crystals of orthorhombic η-Fe2Al5 has been investigated by micropillar compression at room temperature as a function of crystal orientation and specimen size. Plastic flow is observed even at room temperature by the operation of six slip systems; (001)<010>, (001)<110>, (001)<130>, {22‾3}<110>, {311}<1‾03> and {301}<1‾03>. The CRSS values for the six identified slip systems are very high all in the range of 1.1∼1.5 GPa and do not vary much with specimen
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