The scalable synthesis of high-quality single-crystal diamond films remains pivotal for next-generation extreme-performance devices. Iridium substrates offer exceptional promise for heteroepitaxy, yet early-stage growth mechanisms limiting crystal quality are poorly understood. An integrated multiscale investigation combining first-principles DFT calculations, molecular dynamics simulations, and experimental validation is presented to resolve the oriented attachment process governing diamond growth on Ir(100). Robust interfacial bonding at the interface and optimal carbon coverage are revealed to provide thermodynamic driving forces for primary nucleation. A critical angular tolerance enabling defect-free coalescence through crystallographic realignment is identified by molecular dynamics. Concurrent nucleation growth pathways are experimentally confirmed through SEM, AFM, and Raman spectroscopy, where nascent crystallites undergo spontaneous orientational registry to form continuous epitaxial domains. Grain boundary annihilation is observed upon lattice rotation aligning adjacent grains below the critical angle. Crucially, intrinsic atomic steps are generated on the resultant coalesced layer, eliminating conventional etching requirements for homoepitaxial thickening. This work advances fundamental understanding of single-crystal diamond growth mechanisms, facilitating enhanced quality control for semiconductor device manufacturing and quantum applications.

This study investigated the long‐term stability of cemented soil pile foundations in the complex water environment of the Pearl River Delta (PRD). Creep tests of cemented soil were conducted under different moisture conditions, including natural condition, saturated condition, and wet–dry cycling. A creep model was developed by integrating numerical simulations to examine water–stress interaction. Under wet–dry cycling conditions, the required time to achieve stable creep for specimens initially increased, then decreased, and finally increased again with variations in cycle duration. Finally, an innovative creep rate intersection method was proposed to quantify the long‐term strength values of cemented soil under both natural and saturated conditions. The full‐stage creep model developed based on the improved Burgers model significantly outperforms traditional approaches, successfully overcoming the limitation of conventional models in describing the accelerated creep phase. During this stage, it achieves a remarkable goodness‐of‐fit with R ² reaching 0.97. Furthermore, numerical simulations were employed to elucidate the long‐term deformation behavior of subgrade engineering under different moisture conditions.