| 応募部門 | 3.透過電子顕微鏡部門（STEM, 分析等を含む） |
| 題目 | Direct observation of Re segregation at interfacial dislocation core region in crept Ni-based single crystal superalloy |
| 作品の説明 | It is well-known that rhenium (Re) can significantly improve the creep properties of Ni-based single-crystal superalloys. Extensive efforts have been made to determine the spatial distribution of Re in superalloys and the mechanism of how Re affects the mechanical properties of superalloys. However, the results often contradict each other, and still no conclusive understanding has been reached. According to the distribution analysis of Re in superalloys, several hypotheses on the Re effect have been proposed. However, none of those hypotheses have been experimentally validated. After creep test, Re effect has achieved significant improvement of creep property. STEM-HAADF imaging together with EDS mapping could present the heavy atom segregation region at nano-atomic scales. Atomic-scaled images displays interfacial dislocation core structure in the Re-segregation region. These results not only help explain the important “Re effect” in Ni-based superalloys, but also provide a new perspective on improving creep properties of Ni-based superalloys. |
| 学術的価値 | Re cluster that segregated at the interfacial dislocation core region was first observed and experimentally validated using advanced TEM, which could confirm the previous hypothesis. |
| 技術的価値 | Creep test was performed on Ni-based single crystal superalloy with Re addition, which provides the conditions for |
| 組織写真の価値 | STEM-HAADF images and EDS mapping provide the direct evidence of Re segregation region at nano-scale, which also displays the dislocation core structure at atomic scale. |
| 材料名 | Ni-based single crystal superalloy |
| 試料作製法 | Nominal composition (in wt.%) of the second-generation single-crystalline superalloy is 6.2Al, 5.4Cr, 7.2Co, 8.1Ta, 5.8W, 4.8Re and bal. Ni. The ingot was directionally solidified along the [001] direction and had undergone standard heat treatment (1310 °C/5 h + 1310 °C/0.5 h + 1140 °C/8h + 870 °C/16 h) + Air Cooling (AC). Creep tests were conducted at 1100 °C with 130 MPa of stress applied parallel to the [0 0 1] axis. |
| 観察手法 | Scanning transmission electron microscopy (STEM) imaging and EDS analysis were undertaken on a spherical aberration corrected (Cs-corrected) FEI 80–200 Titan G2 TE microscope, operated at 200 kV, equipped with a Super-X, a high-angle annular dark field (HAADF) detector. |
| 出典 | F. Sun, et al. J. Alloy. Comp., 618 (2015), pp. 750-754. |
| 応募者・共同研究者 | 1. Fei SUN, Advanced Institute for Materials Research (AIMR), Tohoku University |
