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Abstract <p>This study investigated the effect of different annealing temperatures on the microstructure and mechanical properties of FeCoNiAl<sub>0.25</sub>Mn<sub>0.75</sub>Ti<sub>0.25</sub> high-entropy alloy (HEA). The as-cast HEA alloy was produced and underwent different annealing temperatures (700 <sup>o</sup>C, 800 <sup>o</sup>C, and 1000 <sup>o</sup>C). The initial microstructure of the as-cast alloy consists of a two-phase mixture of FeCoNi-rich matrix with a face-centered cubic (FCC) structure and TiNiAl-rich regions with a body-centered cubic (BCC) structure. After annealing at 700&#xa0;°C, needle-shaped precipitates were observed within the FCC phase, with a range of 1–2&#xa0;μm in size. As the annealing temperature increases to 800 <sup>o</sup>C, the density of these needle-shaped precipitates significantly increased, and the nanoscale precipitate phase with an L1<sub>2</sub> structure appeared in the matrix. This microstructural feature plays a key role in strengthening the material, resulting in a peak hardness value of ~ 364 HV, the highest yield strength (YS) of ~ 638&#xa0;MPa, and ultimate tensile strength (UTS) of ~ 991&#xa0;MPa. Meanwhile, the fracture elongation (EL) dramatically decreased to 7.56% compared to the as-cast sample. In the annealing condition of 1000 <sup>o</sup>C, both nanoscale and needle-shaped precipitates were partially dissolved, and the TiNiAl-rich BCC phase was significantly coarsened. Consequently, the mechanical properties of hardness, YS, and UTS have noticeably deteriorated. These findings highlight the critical role of thermal treatment in tailoring the microstructural features and mechanical performance of FeCoNiAl<sub>0.25</sub>Mn<sub>0.75</sub>Ti<sub>0.25</sub> HEAs, and provide valuable insights for the design and development of high-strength structural materials.</p> Graphical Abstract <p></p>

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Effect of Annealing Temperature on Microstructure and Mechanical Properties of FeCoNiAl0.25Mn0.75Ti0.25 High Entropy Alloy

  • 期刊论文

  • 发表日期：

    2025年9月18日

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  • Minh Duc Le,
  • Thanh-Dat Nguyen,
  • Thanh Hung Nguyen,
  • Van Tuan Nguyen,
  • Dinh Chien Nguyen,
  • Van Nghia Tran,
  • Hong Hai Nguyen,
  • Soo Yeol Lee,
  • Mai Khanh Pham

摘要

Abstract

This study investigated the effect of different annealing temperatures on the microstructure and mechanical properties of FeCoNiAl0.25Mn0.75Ti0.25 high-entropy alloy (HEA). The as-cast HEA alloy was produced and underwent different annealing temperatures (700 oC, 800 oC, and 1000 oC). The initial microstructure of the as-cast alloy consists of a two-phase mixture of FeCoNi-rich matrix with a face-centered cubic (FCC) structure and TiNiAl-rich regions with a body-centered cubic (BCC) structure. After annealing at 700 °C, needle-shaped precipitates were observed within the FCC phase, with a range of 1–2 μm in size. As the annealing temperature increases to 800 oC, the density of these needle-shaped precipitates significantly increased, and the nanoscale precipitate phase with an L12 structure appeared in the matrix. This microstructural feature plays a key role in strengthening the material, resulting in a peak hardness value of ~ 364 HV, the highest yield strength (YS) of ~ 638 MPa, and ultimate tensile strength (UTS) of ~ 991 MPa. Meanwhile, the fracture elongation (EL) dramatically decreased to 7.56% compared to the as-cast sample. In the annealing condition of 1000 oC, both nanoscale and needle-shaped precipitates were partially dissolved, and the TiNiAl-rich BCC phase was significantly coarsened. Consequently, the mechanical properties of hardness, YS, and UTS have noticeably deteriorated. These findings highlight the critical role of thermal treatment in tailoring the microstructural features and mechanical performance of FeCoNiAl0.25Mn0.75Ti0.25 HEAs, and provide valuable insights for the design and development of high-strength structural materials.

Graphical Abstract