Compositive role of refractory element Mo in improving strength and ductility of face-centered-cubic complex concentrated alloys

Tae Jin Jang, You Na Lee, Yuji Ikeda, Fritz Körmann, Ju Hyun Baek, Hyeon Seok Do, Yeon Taek Choi, Hojun Gwon, Jin Yoo Suh, Hyoung Seop Kim, Byeong Joo Lee, Alireza Zargaran, Seok Su Sohn

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Complex concentrated alloys (CCAs) with a face-centered-cubic (FCC) structure exhibit remarkable mechanical properties, introducing the expansion of compositional space in alloy design for structural materials. The formation of a single solid-solution phase is enabled by configuring various 3d-transition elements, while doping other elements even of a small portion generally leads to the formation of brittle intermetallic compounds. Herein, we demonstrate through a systematic investigation of single FCC (CoNi)100-xMox alloys that a wide range of refractory element Mo can simultaneously improve the strength and ductility while sustaining the solid-solution structure. The addition of Mo with a larger atomic size than those of 3d-transition elements introduces severe lattice distortion in the FCC lattice and causes grain-boundary segregation enriched by Mo atoms. In addition, increasing Mo content effectively reduces the stacking fault energy (SFE). The increased lattice distortion with Mo content enhances the solid-solution strengthening of the alloys. Besides, along with reduced SFE and stabilization of the dislocation emission site by grain-boundary segregation, this elevated solid-solution strengthening increases grain-boundary strengthening, reaching a yield strength of ∼1 GPa. Moreover, the reduction of SFE with increasing Mo results in the transition of dislocation substructures and the refinement of deformation twins, allowing for enhanced strain-hardening capability and thus ∼1.3 GPa tensile strength and ∼50% ductility. Such compositive and synergetic effects of refractory element Mo enable the CCAs with a single FCC solid solution to overcome the strength and ductility trade-off.

Original languageEnglish
Article number119030
JournalActa Materialia
Volume255
DOIs
Publication statusPublished - 2023 Aug 15

Bibliographical note

Publisher Copyright:
© 2023 Acta Materialia Inc.

Keywords

  • Complex concentrated alloy
  • Grain-boundary strengthening
  • Refractory element
  • Solid-solution strengthening
  • Strain-hardening capability

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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