Spatial Grain Orientation Induced Structural Coloration Anisotropy of the Micro V-Shaped Metal Arrays for Metallurgical Structure Characterizing

Nature is the original creator of beauty. Sometimes, the beauty is plain to see, but in some cases, only a suitable stimulation can unveil it. Here, a micro-grating assistant method is used to stimulate the brilliant random structural colors on the surface of polycrystalline metals. In cutting of micro V-shaped gratings on the micro-grains having different orientations, the anisotropic mechanical property of the micro-grains can cause the anisotropic micro-deformation of the geometric profile of the gratings, thereby stimulating the structural colors of the machined surface. As an example, the suitable structural coloration stimulation condition is investigated for the polycrystalline aluminum, considering the cutting depth, tool-included angle, and grating period. Furthermore, the V-shaped gratings are also machined on the polycrystalline tin and copper samples. The results indicate that the grating-based structural coloration method is a potential new technology to characterize the size and shape of the micro-crystals of various polycrystalline metals. Compared with the conventional metallographic analysis method, which uses grinding and polishing technologies to pre-treat the sample, this novel method has unmatched advantages in the high-efficiency, soft metal availability, and micro-area availability.