Ultrafast lasers, with their ultrashort pulse widths and ultrahigh energy densities, have emerged as a powerful tool for modulating the surface morphology and properties of metallic materials. However, the complex interaction between ultrafast lasers and metals—involving multi-scale energy transfer, transient material state evolution, and plasma dynamics—poses significant challenges to understanding the underlying thermal-mechanical mechanisms and surface regulation laws. This review systematically examines the coupled thermal-mechanical processes during ultrafast laser-metal interactions. From the perspective of multi-scale structural responses at the single-point, line-scan, area-scan, and subsurface levels, the physical mechanisms underlying ablation morphology evolution, grain refinement, dislocation proliferation, and residual stress distribution are analyzed in depth. Key advances in surface property modulation strategies based on these mechanisms are reviewed, including direct ultrafast laser shock peening, magnetic field-assisted processing, and the tailoring of optical absorption and radiation properties. Representative results from our research group are highlighted, such as the dynamic evolution of electron-lattice temperatures, time-resolved plasma expansion, and the role of thermal-mechanical coupling in forming micro/nano surface structures. Current challenges—such as the limited understanding of multi-physics coupling, difficulties in precise multi-scale structure control, and the trade-off between processing efficiency and uniformity—are discussed. Future directions are proposed, including the exploration of material responses under extreme conditions, the development of multi-energy field hybrid modulation strategies, and the integration of ultrafast laser processing with artificial intelligence and in-situ monitoring. These efforts are expected to advance ultrafast laser-based surface engineering from "morphology-property modulation" toward "intelligent manufacturing," providing theoretical and technical support for high-performance metal components in aerospace, precision instrumentation, and electronic information applications.

Ultrafast Laser