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<p>Refractory high-entropy alloy (RHEA) is at the forefront of advanced metal materials research due to its exceptional high-temperature mechanical properties, demonstrating significant potential in aerospace and other cutting-edge fields. In comparison with other RHEAs systems, the HfNbTiZr series exhibits superior plasticity at room temperature. Although numerous scholars have systematically investigated its mechanical properties, the understanding of its recrystallization mechanism remains insufficient. Therefore, in this study, the non-equal atomic (Hf<sub>15</sub>Nb<sub>22</sub>Ti<sub>33</sub>Zr<sub>30</sub>)<sub>100−<i>x</i></sub>Al<sub><i>x</i></sub> (where x = 3 and 7 in molar ratio; hereafter referred to as Al<sub>3</sub> and Al<sub>7</sub>) RHEAs were developed and subjected to uniaxial compression and multi-pass rolling. The recrystallization mechanism during deformation heat treatment was examined using Electron Backscatter Diffraction. The results demonstrate that the as-cast Al<sub>3</sub> and Al<sub>7</sub> alloys exhibit typical dendritic structures, while equiaxed crystals are formed after homogenization annealing. Subsequent hot compression at 800&#xa0;°C induces deformation of substructures along grain boundaries, resulting in blurred grain boundaries. After annealing, recrystallization occurs at the grain boundaries. On the other hand, hot compression at 1000&#xa0;°C leads to the disappearance of grain boundaries in the alloy and the uniform distribution of deformation bands within the matrix. Discontinuous recrystallization and continuous recrystallization take place in the meantime after annealing. Multi-pass rolling does not sufficiently induce dynamic recrystallization in the alloy, leaving some coarsely deformed grains present; however, complete recrystallization occurs after annealing. The recrystallization behavior of the alloy is significantly influenced by both the Al content and the deformation temperature. Continuous recrystallization primarily occurs during annealing following compression at 800&#xa0;°C, whereas coordination between continuous and discontinuous recrystallizations characterizes annealing following compression at 1000&#xa0;°C. Full recrystallization of the rolled alloy is achieved after annealing with refined grains. In addition, the recrystallization of alloys with a higher Al content is more likely to occur, which may be caused by lattice distortion caused by Al as a solid solution element.</p>

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Recrystallization Mechanism of Refractory High-Entropy Alloy (Hf15Nb22Ti33Zr30)100−xAlx

  • 期刊论文

  • 发表日期：

    2025年6月13日

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  • Wei Zhang,
  • Yuanyuan Zhang,
  • Xinlong Zhang,
  • Yanjun Wang,
  • Shuzhi Zhang,
  • Shouzhen Cao,
  • Jianchao Han

摘要

Refractory high-entropy alloy (RHEA) is at the forefront of advanced metal materials research due to its exceptional high-temperature mechanical properties, demonstrating significant potential in aerospace and other cutting-edge fields. In comparison with other RHEAs systems, the HfNbTiZr series exhibits superior plasticity at room temperature. Although numerous scholars have systematically investigated its mechanical properties, the understanding of its recrystallization mechanism remains insufficient. Therefore, in this study, the non-equal atomic (Hf15Nb22Ti33Zr30)100−xAlx (where x = 3 and 7 in molar ratio; hereafter referred to as Al3 and Al7) RHEAs were developed and subjected to uniaxial compression and multi-pass rolling. The recrystallization mechanism during deformation heat treatment was examined using Electron Backscatter Diffraction. The results demonstrate that the as-cast Al3 and Al7 alloys exhibit typical dendritic structures, while equiaxed crystals are formed after homogenization annealing. Subsequent hot compression at 800 °C induces deformation of substructures along grain boundaries, resulting in blurred grain boundaries. After annealing, recrystallization occurs at the grain boundaries. On the other hand, hot compression at 1000 °C leads to the disappearance of grain boundaries in the alloy and the uniform distribution of deformation bands within the matrix. Discontinuous recrystallization and continuous recrystallization take place in the meantime after annealing. Multi-pass rolling does not sufficiently induce dynamic recrystallization in the alloy, leaving some coarsely deformed grains present; however, complete recrystallization occurs after annealing. The recrystallization behavior of the alloy is significantly influenced by both the Al content and the deformation temperature. Continuous recrystallization primarily occurs during annealing following compression at 800 °C, whereas coordination between continuous and discontinuous recrystallizations characterizes annealing following compression at 1000 °C. Full recrystallization of the rolled alloy is achieved after annealing with refined grains. In addition, the recrystallization of alloys with a higher Al content is more likely to occur, which may be caused by lattice distortion caused by Al as a solid solution element.