Ultra-short pulsed laser ablation of decagonal AlCoNi and AlCoCuNi quasicrystals

Abstract

Al70Co20Ni10 and Al70Co15Cu10Ni5 (at%) decagonal quasicrystals (DQCs) were subjected to femtosecond laser ablation at a laser wavelength of 800 nm, in deionized water (DI). The generated nanoparticles (NPs) confined within the liquid medium were studied for optical and structural properties. The structural analysis revealed the retention of the targets phase in the NPs. In case of Al70Co20Ni10, formation of Al3Ni2 phase was confirmed through the SAED patterns and HRTEM micrographs. Contrary to this, the formation of Al-Ni phase was not observed in Al70Co15Cu10Ni5. This is attributed to the presence of Cu in the latter sample, which restricts the mixing of Ni with Al. The HRTEM micrographs in both cases showed that Al2O3 was present at the edges of the NPs. The optical analysis confirmed the formation of Al2O3 in both cases. However, in the case of Al70Co15Cu10Ni5, a very weak signal corresponding to CuO was detected. This is attributed to the diffusion of Cu along with Al at the edge. The ablated region of the target’s surface was studied for the formation of laser-induced periodic surface structures (LIPSS) also known as ripples, and the type of ripples formed was identified.