摘要
We investigate the surface stress of solid-liquid diffusive interfaces at equilibrium using the phase field crystal model in two dimensions. To analytically study the surface energy dependence on elastic strains, we employ the amplitude equation formalism and recast the free energy functional in terms of strains and amplitudes of density waves to examine the intricate coupling between them. For planar interfaces, the surface stress and its anisotropy are explored using the phase field crystal model and its amplitude equations. The anisotropy of surface stress is shown to be closely related to the anisotropic density waves across the interface, and a stronger anisotropy is observed in the surface stress than that in the surface energy. In addition, to investigate the curvature effect, we examine resultant strain fields at equilibrium within nanoparticles of various sizes subjected to their surface stresses. The measured strains are compared with the classical sharp interface model. The discrepancy in strain fields arises as the size of nanoparticles becomes smaller which suggests a curvature dependent surface stress for diffusive interfaces. We construct the effective surface stress using the measured strain fields and classical linear elasticity theory. The overall magnitude of the effective surface stress decreases with the radius of the nanoparticle, and the effective surface stress is shown to be more isotropic for small nanoparticles.