Metals with nanoscale crystal grains are super-strong although they do not retain their structure at higher temperatures. As a result, it is challenging to explore their high strength during materials applications. In a new report now published on Science, X. Y. Li and a team of scientists in materials science and engineering at the Chinese Academy of Sciences and Shanghai Jiaotong University in China, found a minimum-interface structure in copper (Cu) with 10-nanometer-sized grains, which they combined with a nanograin crystallographic twinning network to retain high strength at temperatures just below the melting point. The discovery provided a different path to obtain stabilized nanograined metals for metallurgy and materials engineering applications.