Microstructure and mechanical property of novel L12 nanoparticles-strengthened CoFeNi-based medium entropy alloys

Lei Wang, Xinyuan Wu, Haijun Su, Bo Deng, Gang Liu, Zhenhua Han, Yanning Su, Yuandong Huang, Yunpeng Zhang, Jun Shen, Guojun Zhang

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31 Scopus citations

Abstract

A novel L12 nanoparticles-strengthened (CoFeNi)84Ti8V8 medium entropy alloy (MEA) is fabricated. It has typically equiaxed grains (mean grain size: ∼65 μm) in which the near-spherical L12 particles (mean size: ∼23 nm) are uniformly distributed with a volume fraction of ∼45%. This L12 nanoparticle is identified as the novel (Ni,Co,Fe)3(Ti,V) phase. (CoFeNi)84Ti8V8 MEA has an excellent combination of high yield strength (∼950 MPa) and ultimate tensile strength (∼1394 MPa) and good ductility (∼25%). Compared to single-phase (fcc) CoFeNi base alloy, the yield strength and ultimate tensile strength of (CoFeNi)84Ti8V8 MEA increase by ∼428% and ∼215%, respectively. This is mainly attributed to the precipitation strengthening of L12 nanoparticles. The dimple features in the fracture surface imply a good ductility. Moreover, the main deformation mode is dominated by dislocation slips and microbands.

Original languageEnglish
Article number142917
JournalMaterials Science and Engineering: A
Volume840
DOIs
StatePublished - 18 Apr 2022

Keywords

  • Medium entropy alloy
  • Precipitation strengthening
  • Tensile property

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