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<p>A series of AlCoCr<sub><i>x</i></sub>FeNi<sub>2.2</sub> (<i>x</i> = 0, 0.3, 0.7, 1.1, 1.5, 1.9, 2.3) high-entropy alloys were designed and prepared. The effects of the Cr content on the microstructures and mechanical properties of the AlCoCr<sub><i>x</i></sub>FeNi<sub>2.2</sub> alloys were studied. All the alloys consisted of face-centered cubic (FCC) and body-centered cubic (BCC) phases. The Cr-free AlCoFeNi<sub>2.2</sub> alloy exhibited a fine alternating lamellar eutectic structure, which became coarser with increasing Cr content. When <i>x</i> = 2.3, the lamellar eutectic structure disappears. Room temperature uniaxial tensile tests revealed significant changes in the mechanical properties with increasing Cr content. For 0 ≤ <i>x</i> ≤ 1.1, with increasing Cr content, the yield strength and hardness of the alloy decrease, whereas the ductility increases. Conversely, for 1.1 ≤ <i>x</i> ≤ 2.3, increasing the Cr content resulted in a higher yield strength and hardness of the alloy, accompanied by a decrease in ductility. The AlCoCr<sub>0.7</sub>FeNi<sub>2.2</sub> alloy exhibited superior overall mechanical properties at room temperature. The tensile yield strength, hardness, and elongation were 472.9&#xa0;MPa, 294.8 HV, and 26.3%, respectively. Uniaxial tensile tests on the AlCoCr<sub>0.7</sub>FeNi<sub>2.2</sub> alloy at various temperatures and strain rates revealed that the strength increased with increasing temperature and decreasing strain rate. A mathematical description of the effects of temperature and strain rate on the strength of an alloy can be given by the Arrhenius-type equation. These results demonstrate that the AlCoCr<sub>0.7</sub>FeNi<sub>2.2</sub> alloy maintains excellent properties even at elevated temperatures.</p>

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Effects of Chromium Content, Temperature and Strain Rate on Microstructure and Mechanical Properties of As-Cast AlCoCrxFeNi2.2 High-Entropy Alloys

  • 期刊论文

  • 发表日期：

    2025年8月21日

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  • Mingyun Yu,
  • Tingjun Song,
  • Jingan Chen,
  • Peipei Sun,
  • Shijing Yan,
  • Jinming Zhu,
  • Cailiu Yin

摘要

A series of AlCoCrxFeNi2.2 (x = 0, 0.3, 0.7, 1.1, 1.5, 1.9, 2.3) high-entropy alloys were designed and prepared. The effects of the Cr content on the microstructures and mechanical properties of the AlCoCrxFeNi2.2 alloys were studied. All the alloys consisted of face-centered cubic (FCC) and body-centered cubic (BCC) phases. The Cr-free AlCoFeNi2.2 alloy exhibited a fine alternating lamellar eutectic structure, which became coarser with increasing Cr content. When x = 2.3, the lamellar eutectic structure disappears. Room temperature uniaxial tensile tests revealed significant changes in the mechanical properties with increasing Cr content. For 0 ≤ x ≤ 1.1, with increasing Cr content, the yield strength and hardness of the alloy decrease, whereas the ductility increases. Conversely, for 1.1 ≤ x ≤ 2.3, increasing the Cr content resulted in a higher yield strength and hardness of the alloy, accompanied by a decrease in ductility. The AlCoCr0.7FeNi2.2 alloy exhibited superior overall mechanical properties at room temperature. The tensile yield strength, hardness, and elongation were 472.9 MPa, 294.8 HV, and 26.3%, respectively. Uniaxial tensile tests on the AlCoCr0.7FeNi2.2 alloy at various temperatures and strain rates revealed that the strength increased with increasing temperature and decreasing strain rate. A mathematical description of the effects of temperature and strain rate on the strength of an alloy can be given by the Arrhenius-type equation. These results demonstrate that the AlCoCr0.7FeNi2.2 alloy maintains excellent properties even at elevated temperatures.