Grain-boundary engineering is pivotal to fully utilize the mechanical, electrical, and thermal-transport properties of various materials. However, current methods in metallurgy rely almost exclusively on top-down approaches, making precise grain-boundary engineering, especially at nanoscale, difficult to achieve. Herein, we report a method to produce tailored grain-boundary conditions with nanoscale precision from colloidal metal nanocrystals through surface treatment followed by a pressure-sintering process. The resulting bulk grain-boundary materials (which we call “nanocrystal coins”) possess a metal-like appearance and conductivity while inheriting the original domain features of the nanocrystal building blocks. Nanoindentation measurements confirmed the superior mechanical hardness of the obtained materials. Further, we use this method to fabricate, for the first time, a single-component bulk metallic glass from amorphous palladium nanoparticles. Our discovery may spur the development of new materials whose functionality crucially depends on the domain configuration at nanoscale, such as superhard materials, thermoelectric generators, and functional electrodes.

晶界工程对于充分利用各种材料的机械，电气和热传递特性至关重要。但是，目前的冶金方法几乎完全依靠自上而下的方法，因此很难实现精确的晶界工程，尤其是在纳米级。本文中，我们报道了一种通过表面处理，然后进行压力烧结工艺，从胶体金属纳米晶体中以纳米级精度生产定制的晶界条件的方法。所得的大块晶界材料（我们称为“纳米晶体硬币”）具有金属般的外观和导电性，同时继承了纳米晶体构件的原始畴特征。纳米压痕测量证实了所获得的材料具有优异的机械硬度。进一步，我们首次使用这种方法从非晶态钯纳米粒子制造单组分块状金属玻璃。我们的发现可能会刺激新材料的开发，这些新材料的功能至关重要地取决于纳米级的畴结构，例如超硬材料，热电发生器和功能性电极。