Rapid electrical-current-activated sintering achieves robust cladding with uniform nanocrystalline grains

Abstract

Nanocrystalline (NC) metals possess high strength due to its extremely small grain size, but the strength-plasticity trade-off, poor thermal stability, and limitation to a few micrometers in size have seriously hampered their widespread application for a long time. Here, we propose a universal and facile strategy to solve these problems all at once, by exploiting the synergistic aspect of rapid electrical-current-activated sintering (RECAS) and multi-component NC alloy. We demonstrate RECAS as an efficient way to achieve dense and robust claddings versatile in dimensions (i.e., ≥1 mm in thickness), also with uniform NC grain sizes. The NC CoCrNi medium-entropy alloy cladding is used to demonstrate the simultaneous realization of excellent strength-plasticity combination, and unprecedented high thermal stability of NC grain size up to ∼ 0.84T_m (T_m, melting point), and the robust performance in terms of resistance to wear, corrosion and cavitation erosion. These advances open an avenue to a much-expanded repertoire of available parts made of NC metals/alloys (including their size, shape and composition), as well as an increased flexibility with regard to property combinations that extend application possibilities.