Flexible and controllable fabrication of micro-nano structures on metallic glasses (MGs) endow them with more functional applications, but it is still challenging due to the unique mechanical, physical, and chemical properties of MGs. In this study, inspired by a new physical phenomenon observed in the nanosecond laser-MG interaction (i.e., the surface structure is transformed from the normally observed microgroove into the micro-nano bulge at a critical peak laser power intensity), a nanosecond laser "pulling" method is proposed to pattern the MG surface. The formation mechanism and evolution of the micro-nano bulge are investigated in detail, and accordingly, various micro-nano structures including the unidirectional stripe, pillar, cross-hatch patterns, "JLU", circle, triangle, and square, are derived and created on the MG surface, which affects the surface optical diffraction. Overall, this study provides a highly flexible and controllable method to fabricate micro-nano structures on MGs.
Keywords: marangoni effect; metallic glass; micro-nano bulge pattern; nanosecond lasers; volume expansion.
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