Formation of leaf-shaped microstructure on Zr-based metallic glass via nanosecond pulsed laser irradiation

Abstract Formation of regular micro/nano-structures on the surface of metallic glasses (MGs) is beneficial to their functional applications. To pattern the MG surface, in this work, a polished Zr-based MG sample was processed by using a nanosecond pulsed laser under various parameters. Experimental results showed that the regular leaf-shaped microstructure consisting of ripples and vein-like structures was generated in the irradiated area. The effects of processing parameters, including the average power, scanning speed, repetition frequency and pulse overlap rate, on the formation and evolution of leaf-shaped microstructure were investigated in detail. Furthermore, by analyzing the surface characteristics and morphological evolution, the formation mechanism of the leaf-shaped microstructure was analyzed. The ripples with spacing slightly smaller than the wavelength of incident laser were caused by interaction of the incident laser and excited molten surface waves, and the vein-like structures were formed by the subsequent laser pulses induced evolution of precedingly generated micro-cracks. The interaction between the ripples and the vein-like structures resulted in the formation of the leaf-shaped microstructure. After patterning, the MG surface with leaf-shaped microstructure showed enhanced hydrophilicity.