▎ 摘　　要

The CVD of graphene on metal substrates serves as an ideal platform for studying the nucleation and growth of two-dimensional crystals. In this paper, the size distribution and shape transformation of graphene domains at early stages of CVD are investigated. The transformation of round-shaped graphene disks into hexagonal domains during atmospheric pressure (AP)CVD on copper substrates is identified. The critical transformation size from graphene disks to hexagonal domains is similar to 0.8?mu m2 according to the size distribution statistics.