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<p>Porous metals are extensively utilized as core materials in sandwich composite structures due to their excellent energy absorption capabilities. To achieve super high energy absorption, this study designed a porous structure full of microbending sites and made of easily sintered tough FCC Al<sub>0.5</sub>CoCrFeNi<sub>2</sub> high-entropy alloy (HEA). The HEA structures were synthesized by freeze-casting with gas-atomized powders and then sintered. The spherical particles with a mean particle size of 13.12&#xa0;μm were interconnected with appreciable necks and remained in their original single FCC phase after sintering at 1250 ℃ for 1&#xa0;h. Two main processing parameters, solid contents of 20 and 25 vol% in the slurry and cooling rates of 2, 5, and 10 ℃ min<sup>−1</sup> of the slurry, were monitored in freeze-casting to see their effects on the microstructures and mechanical behaviors of the porous HEA. In addition to the volume shrinkage of porous HEA ranging from 50 to 68%, porosity, elastic modulus, yield strength, densification strain, plastic strain, and energy absorption were in the range of 44.7–58%, 5.49–9.15 GPa, 57–120&#xa0;MPa, 66–80%, 64–79%, and 178–526&#xa0;MJ&#xa0;m<sup>−3</sup>, respectively. The record high energy absorption of 526&#xa0;MJ&#xa0;m<sup>−3</sup> with a plastic strain of 79% was achieved by the 20 vol% solid sample under a cooling rate of 10 ℃ min<sup>−1</sup>. The dominant compressive failure mode involved progressive collapse to fill the pores by microbending at necks formed in every segment surrounding the pores, and a large percentage of volume underwent significant plastic flow by microbending. Tough FCC HEA was also crucial to the super energy absorption performance since each microbending could absorb energy as high as possible without fracture before densification. In summary, by integrating freeze-casting and gas atomization techniques, novel lightweight porous HEA can be developed for various engineering applications requiring high energy absorption under impact or collision.</p>

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Super Energy Absorption of Lightweight Porous Al0.5CoCrFeNi2 High-Entropy Alloys Fabricated by Gas Atomization Plus Freeze-Casting Techniques

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  • 出版模式：

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  • 发表日期：

    2025年9月13日

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  • Kuan-Cheng Lai,
  • Ko-Kai Tseng,
  • Jien-Wei Yeh,
  • Shih-Hsun Chen,
  • Yen-Fang Song,
  • Gung-Chian Yin,
  • Po-Yu Chen

摘要

Porous metals are extensively utilized as core materials in sandwich composite structures due to their excellent energy absorption capabilities. To achieve super high energy absorption, this study designed a porous structure full of microbending sites and made of easily sintered tough FCC Al0.5CoCrFeNi2 high-entropy alloy (HEA). The HEA structures were synthesized by freeze-casting with gas-atomized powders and then sintered. The spherical particles with a mean particle size of 13.12 μm were interconnected with appreciable necks and remained in their original single FCC phase after sintering at 1250 ℃ for 1 h. Two main processing parameters, solid contents of 20 and 25 vol% in the slurry and cooling rates of 2, 5, and 10 ℃ min−1 of the slurry, were monitored in freeze-casting to see their effects on the microstructures and mechanical behaviors of the porous HEA. In addition to the volume shrinkage of porous HEA ranging from 50 to 68%, porosity, elastic modulus, yield strength, densification strain, plastic strain, and energy absorption were in the range of 44.7–58%, 5.49–9.15 GPa, 57–120 MPa, 66–80%, 64–79%, and 178–526 MJ m−3, respectively. The record high energy absorption of 526 MJ m−3 with a plastic strain of 79% was achieved by the 20 vol% solid sample under a cooling rate of 10 ℃ min−1. The dominant compressive failure mode involved progressive collapse to fill the pores by microbending at necks formed in every segment surrounding the pores, and a large percentage of volume underwent significant plastic flow by microbending. Tough FCC HEA was also crucial to the super energy absorption performance since each microbending could absorb energy as high as possible without fracture before densification. In summary, by integrating freeze-casting and gas atomization techniques, novel lightweight porous HEA can be developed for various engineering applications requiring high energy absorption under impact or collision.