| Aug 12, 2024 |
Metal with nanoscale voids outperforms void-free samples mechanically
(Nanowerk News) Voids or pores were usually viewed as fatal flaws that can severely degrade material's mechanical performance and were required to be eliminated in manufacturing.
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However, a research team led by Prof. JIN Haijun from the Institute of Metal Research (IMR) of the Chinese Academy of Sciences proposed that the presence of voids is not always hazardous. Instead, voids can be beneficial if they are added "properly" in the material.
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They demonstrated that metal with large-population nanoscale voids shows improved mechanical performance compared to samples without voids.
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This work was published in Science ("Strengthening gold with dispersed nanovoids").
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The new material is dubbed nanovoid dispersed gold (NVD Au). It contains a huge number of nanoscale voids, with void size varying between a few and several hundred nanometers. These voids distribute uniformly throughout the material. NVD Au was made by combining a corrosion process called dealloying with compression and thermal annealing treatments.
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| The TEM and 3D reconstruction images of nanovoid dispersed gold. (Image: Institute of Metal Research)
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The researchers found that NVD Au shows improved strength and ductility in tension than that of the fully-dense Au. In other words, NVD Au with dispersed nanovoids is capable of withstanding higher loads and can be pulled to longer lengths without fracture.
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This is opposite to the effect of large voids observed in materials prepared by powder sintering or additive manufacturing. The excellent properties of NVD Au are attributed to the enhanced dislocation-surface interactions and the suppressed crack nucleation in this structure.
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"We achieved both NVD strengthening and density reduction simultaneously, and thus realized lightweighting," said JIN. "Also, it does not involve any change of composition or phase, so that the excellent physical/chemical properties of the base material can be largely preserved."
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This strengthening approach may be explored for application in many areas, ranging from portable electronics to aviation manufacturing.
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