液态金属在铸造、焊接、柔性电子器件、新型电池和核工业等多个领域中具有广阔的应用前景，其浸润性显著影响着材料的性能和应用效果，因而吸引了研究者广泛的关注。然而，目前关于液态金属浸润性与调控的研究相对匮乏且局限，存在涉及浸润体系有限、调控不够全面、基体表面结构影响不明等诸多问题，尤其缺乏普适、便捷、高效的调控手段，严重制约了液态金属材料的进一步发展和实际应用。本文基于激光与材料的相互作用机理和表面润湿理论，在模具钢、铜、钽等多种基体表面制备出丰富的微结构，系统研究了室温镓基液态金属、熔融锡和熔融铈等典型液态金属在多种微结构表面上的润湿行为和演变规律，证实基体表面成分与环境条件决定体系的初始亲疏液特性、基体表面结构进一步放大体系浸润性的基本规律，总结分析了多种体系中影响液态金属润湿状态的基体表面微结构钉扎三相接触线和诱发毛细铺展等现象，丰富了对不同液态金属浸润体系的研究，拓展了针对液态金属的浸润性调控思路。提出了改变液态金属-基体体系初始浸润性叠加激光制备表面微结构的双重调控策略，在H13模具钢、铜和钽等多种常用基体表面上制备出独特的微结构，结合表面成分调整、环境条件改变等辅助手段，便捷灵活地实现了室温镓基液态金属的超亲液/超疏液化调控、熔融锡的疏液/超疏液化调控和高温熔融铈的超亲液/疏液化调控，极大拓宽了液态金属浸润性的调控范围。通过对液态金属浸润性的可控调节，进一步实现了相应体系中多种性能的调控和优化。增强基体表面的疏液性能，实现了多种金属基体对室温镓基液态金属抗粘附性能和耐腐蚀性能的显著提升；对金属铜表面进行亲液化微结构处理，以室温镓基液态金属为热界面材料，铜基体间的界面热阻率大幅降低至"0.37 " 〖"mm" 〗^"2" "?K/W" ，仅为原始铜基体试样数值的四分之一和铜基体干接触时数值的万分之三；经激光处理制备出H13模具钢表面的微结构，实现了锡/模具钢界面结合强度在0.66 ~1.05 N/mm2范围内的大幅调控。本文研究成果丰富、拓宽了对液体金属润湿行为的理解，显著增强了对液态金属浸润性的调控能力，使液态金属材料在柔性电子器件、热管理、异种材料连接和熔融金属精炼脱模等多个领域中的应用潜力得到了极大拓展。
Liquid metals are promising in many fields, e.g., casting, welding, flexible electronics, newly-developed batteries and nuclear fusion, etc. The wetting behaviors of liquid metals on various substrate surfaces have a prominent impact on the properties of the materials and the performance of their final products, and have thus attracted great attention of researchers. However, up to now, the studies relevant to the wettability of liquid metals and the associated control remain insufficient and limited, and there still exist several challenges which severely impede the further development and practical applications of liquid metals. For example, the covered wetting systems were limited, the control of the wetting of liquid metals kept partial and inadequate, the effect of the substrate surface micro-structures remained unclear, and most importantly, a controlling method which was universal, convenient as well as powerful was still lacking.In this work, a variety of micro-structured surfaces was successfully fabricated on various substrates, e.g., steel, copper and tantalum, and the wetting behaviors of many typical liquid metals, e.g., room-temperature gallium-based liquid metal, molten tin and molten cerium, etc., on the obtained surfaces were systematically studied based on the interaction mechanism between laser and materials and the wetting theory. Basic rules that the composition of substrate surfaces and the environmental conditions would determind the initial wettability of the wetting systems, and that the surface micro-structures of the substrates would further strengthen their wetting properties were proved to be applicable for liquid metals. Phenomena related to the substrate surface micro-structures, i.e., the three-phased contact line (TPCL) pinning effect and the liquid metal wicking effect, which were both observed in different systems and had an effect on their wetting behaviors were summarized and theoretically analyzed. The knowledge about different liquid metal wetting systems was enriched by this work, and the ways of controlling the liquid metal wettability were opened and widened as well.A novel, practical, and efficient controlling strategy which based on the regulation of the initial wettability of the liquid metal-substrate wetting system plus with a laser surface-micro-structuring step was proposed. Through this strategy, room-temperature gallium-based liquid metal could be turned super-lyophilic or super-lyophobic, molten tin became more lyophobic or even super-lyophobic, and molten cerium achieved to be super-lyophilic or more lyophobic at a relatively high temperature on laser-treated H13 steel, copper, tantalum or other common substrate surfaces with typical micro-structures under the assistance of the substrate surface composition modification and the environmental condition alteration.Variety of properties of the discussed systems could be optimized by controlling the liquid metal wetting behaviors flexibly. The anti-adhesion properties and the anti-corrosion properties against room-temperature gallium-based liquid metal of many metallic substrates were significantly strengthened by improving their lyophobicity. By fabricating micro-structured copper surfaces with better lyophilicity, the thermal interface resistance (TIR) between two copper blocks using room-temperature gallium-based liquid metal as the thermal interface material (TIM) was lowered down to "0.37 " 〖"mm" 〗^"2" "?K/W" , which was only a quarter of the value of the sample with bare copper surfaces, and 0.03% of the one without any TIMs. Besides, the bonding strength of the tin/H13 steel interface was able to vary within a large range of 0.66 ~1.05 N/mm2 with different laser-micro-structured H13 steel surfaces.This paper enriched and widened the relevant understanding of the wetting of liquid metals, and significantly strengthened the capability of efficiently and conveniently controlling their wetting behaviors as well. The results were meaningful and helpful to enhance the potential of liquid metals in applications like flexible electronics, thermal management, dissimilar material connection, molten metal refining and demolding, etc.
