Transient Hydrogen-Manipulated Nonequilibrium Kinetics of Abnormal Grain Growth for Single-Crystal Copper Foils

Single-crystal copper foil is a distinguished material for electrical transmission, thermal conduction, and two-dimensional material epitaxy. However, the speed of producing a large-area single-crystal copper foil by annealing polycrystalline copper is limited by slow nucleation rates of abnormal grains constrained by thermodynamic equilibrium, as well as by homogeneous nucleation, which prevents single-crystalline growth. Here, we propose a transient hydrogen introduction method based on a nonequilibrium kinetic strategy. By introducing hydrogen at high temperature, we instantly induce the formation of a desired density of abnormal grains while keeping the normal grains nearly unchanged in size, thereby enabling the accelerated growth of abnormal grains into a single crystal. This method enables rapid single-crystallization during high-temperature annealing, by which a 6 cm × 18 cm polycrystalline copper foil can be converted into a single crystal within a few minutes at the annealing temperature, representing an order-of-magnitude acceleration in abnormal grain growth kinetics compared with conventional annealing. This work provides mechanistic insight into nonequilibrium abnormal grain growth and offers a controllable route for the efficient high-temperature processing of large-area single-crystal copper foils.