A novel method for fabricating micro-dimple arrays with good surface quality on metallic glass substrate by combining laser irradiation and mechanical polishing under wax sealing

Surface micro-patterning is an emerging technique to endow a wide range of materials with specific functions, such as superhydrophobicity and anti-reflection, but it is still technically challenging and inordinately expensive via existing manufacturing approaches. Compared with crystalline metals, metallic glasses (MGs) are talented with some unique mechanical and chemical properties due to their isotropic internal structure. Here, a novel two-step method, involving nanosecond pulsed laser irradiation and mechanical polishing, was proposed to fabricate micro-dimple arrays with good surface quality on the MG substrate. In the first step, multi-pulse laser irradiation experiments were performed to study the correlation between the peak laser power intensity and the feature sizes of the micro-dimple (i.e. the depth and diameter of the micro-dimple as well as the height of the pile-up), and then various micro-dimple arrays were fabricated on the MG substrate by adjusting the peak laser power intensity and the interval between adjacent laser shots. Subsequently, aiming at improving the surface quality, the micro-dimple arrays were mechanically polished under wax sealing. The experimental results indicated that after polishing, the pile-ups around the micro-dimples were completely removed, and at the same time, the surface quality of their inner walls was improved. Furthermore, based on experimental results, the possible material removal mechanism during polishing was discussed. This study provides a convenient method to fabricate micro-dimple arrays with good surface quality on the MG substrate, which would be one of the potential alternatives for large-area, low-cost micro/nano-manufacturing.