Formation of Nano-sized Films on the Surface of Pure Al by Nd: YAG Pulsed Laser Irradiation
Chengyun Cui, Jiandong Hu, Yue Yang, Hongying Wang and Zuoxing Guo
Experiments were conducted to investigate the ultra-fine microstructures on the surface layer of pure Al by Nd:YAG pulsed laser irradiation. When lower laser power densities were employed, nano-crystalline films with a grain size of 50–120 nm were formed on the pure Al surface. When larger laser power densities were employed, the films with small spherical grains of 150–300 nm were formed. The formation process of nano-crystalline films on the pure Al surface was explained by an increase in the laser power density of the solidification process following the one-dimensional numerical simulation of the thermal process. The finer nano-structures were significant features, which were also confirmed by TEM. XRD showed that nano-structured films had almost the same phase compositions with the original pure Al surface. It was found that the micro-hardness values of all these Al nano-films were higher than that of pure Al without laser treatment.
Keywords: Nano-structured films, Pure Al, Nd:YAG pulsed laser, numerical simulation, TEM, microhardness.