Abstract |
Properties of metallic materials depend strongly upon structure and populations of grain boundaries (GBs) and other interfaces. For instance, metals’ strength increases at smaller grain sizes with higher GB densities, especially in the nanometer scale. However, generating interfaces at high densities is technically challenging because they may become unstable under thermal and mechanical activation. In recent decades, we explored different strategies for stabilizing interfaces in metals and discovered several novel metastable nanostructures with extremely-dense interfaces. In this talk, I will introduce (1) extremely-dense lamellate structures with low-energy interfaces (such as nano-twinned structures and sub-nanostructures with negative-excess-energy interfaces), and (2) extremely-fine nanograined structures with 3D periodical minimal surface (TPMS) GB networks, namely ‘‘Schwarz crystal’’. The metals with extremely-dense interfaces exhibit superior stability and extraordinary properties comparing with the ordinary polycrystalline counterparts. Formation, structure characteristics, structure-property relationship, as well as perspectives of these extreme crystals will be discussed in a number of metals and alloys.
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