Multiscale structural characterization of yttria dispersed copper alloys fabricated by hot isostatic processing of mechanically alloyed powders

Yusuke Shimada, Makoto Kazukawa, Yoshimitsu Hishinuma, Ken ichi Ikeda, Hiroyuki Noto, Bing Ma, Masaki Takeguchi, Takeo Muroga, Toyohiko J. Konno

Research output: Contribution to journalArticlepeer-review

Abstract

Multi-scale characterization techniques, including computed tomography (CT) based on serial sectioning by focused ion beam (FIB) and scanning transmission electron microscopy (STEM), have been employed to elucidate the microstructural hierarchy inside yttria (Y2O3) dispersed copper alloys designed for fusion reactors. The alloys were fabricated by the combination of mechanical alloying of metal and oxide powders and subsequent hot isostatic pressing. Optical microscopy, together with electron micro-probe analysis revealed bimodal size distribution of powders, where coarse Cu powders of several hundred micrometer are composed of metallic core surrounded by a crust of Cu oxides, while fine powders of several ten micrometer are mostly of oxides. Scanning electron microscopy (SEM) on the fabricated bulk alloys revealed heterogeneous inner structure, which is best described by an assembly of large Cu grain regions bordered by small Cu grain regions. Distribution of Y2O3 particles are visualized three dimensionally by serial sectioned FIB-SEM images and by CT-STEM, both of which revealed the particles are enriched in small Cu grain regions. These multi-scale characterization, together with mechanical bend testing, demonstrated that excess Y2O3 particles in grain boundaries leads to brittle fracture, while that large Cu grains are responsible for the ductility of the alloy.

Original languageEnglish
Article number100892
JournalMaterialia
Volume14
DOIs
Publication statusPublished - 2020 Dec

Keywords

  • 3D analysis
  • Copper alloys
  • Dispersion strengthening
  • Fusion materials

ASJC Scopus subject areas

  • Materials Science(all)

Fingerprint Dive into the research topics of 'Multiscale structural characterization of yttria dispersed copper alloys fabricated by hot isostatic processing of mechanically alloyed powders'. Together they form a unique fingerprint.

Cite this