【論文・プレスリリース】大阪大学から、「金属3D プリンティングに特異な高強度階層組織の変形挙動を解明」に関するActa Materialiaへの論文掲載に関するプレスリリースを14時付で行いました。同時に論文がOAとして掲載されました。JST-Crestの成果です。
2025-11-11
Ken Cho, Kippei Yamashita, Shinnosuke Kakutani, Takuma Saito, Taisuke Sasaki, Katsuhiko Sawaizumi, Masayuki Okugawa, Yuichiro Koizumi, Tsuyoshi Mayama, Taichi Kikukawa, Ozkan Gokcekaya, Takuya Ishimoto, Hajime Kimizuka, Wu Gong, Takuro Kawasaki, Stefanus Harjo, Takayoshi Nakano, Hiroyuki Y. Yasuda*: Effect of nanoscale cellular structure on the mechanical properties of Inconel 718 with unique hierarchical structure fabricated by laser powder bed fusion, Acta Materialia.
DOI: https://doi.org/10.1016/j.actamat.2025.121696
プレスリリース原稿はこちら
論文はこちら
Abstract
The deformation behavior and strengthening mechanism of Inconel 718 with a hierarchical structure composed of microscale crystallographic lamellar microstructure (CLM) and nanoscale cellular structure, fabricated by laser powder bed fusion, were clarified via nanoscale microstructural and in-situ neutron diffraction analyses. The CLM is a layered structure parallel to the building direction (BD) and consists of relatively wide main and narrow sub-layers with <110> and <100> orientations, respectively, with respect to BD. This is the first study to demonstrate that the yield stress of the alloys depends strongly on deformation stresses of the sub-layers, even though Schmid factors of the primary slip system for both layers are the same. The sub-layer continues to deform elastically even beyond the micro-yield point of the main layer, which results in the macroscopic strengthening at an early stage of deformation. On the other hand, the cellular structure is formed in both layers, associated with a dendritic cell growth along <100> direction, Nb segregation between the cells and an accumulation of dislocations to decrease a residual stress. The cell boundaries with numerous dislocations and Nb segregation act as a strong barrier to dislocation motion resulting in a stress increase through the Hall-Petch law, even though they are low-angle grain boundaries. The spacing and morphology of the cell boundary depend strongly on fabrication conditions. The optimized cellular structure provides significant strengthening comparable to or greater than that caused by large-angle grain boundaries, thereby increasing the macroscopic strength of the alloys through hardening of the sub-layer.