Comparative study of amorphous and crystalline Zr-based alloys in response to nanosecond pulse laser ablation

Abstract

In this work, we comprehensively investigate the response of amorphous and crystalline Zr-based alloys under nanosecond pulse laser ablation. The in situ multiphysics processes and ablation morphologies of the two alloy targets are explored and compared. The results indicate that the dynamics of laser-induced plasma and shock waves obey the idea blast wave theory and are insensitive to the topological structures of targets. Both targets experience significant superheating and culminate in explosive boiling. This ablation process leads to the formation of a hierarchical structure in the resultant ablation crater: microdents covered by widespread nanovoids. The amorphous target shows shallower microdents and smaller nanovoids than their crystalline counterparts because the former has a smaller heat-affected zone and experiences a higher degree of superheating. The hierarchical structure can adjust the surface wettability of targets from initial hydrophilic to hydrophobic, showing an increase of the contact angle approximately 119% for amorphous alloy compared with the crystal approximately 64%. This work demonstrates that amorphous alloys have a better performance against nanosecond pulse laser ablation and provides a feasible and one-step method of wettability modification for either amorphous or crystalline alloys.

摘要

本文系统性地对比研究了非晶态与晶态锆基合金对纳秒脉冲激光的烧蚀响应, 主要关注两种合金靶的多物理烧蚀过程以及 靶表面烧蚀形貌. 结果表明, 激光诱导等离子体及其产生的冲击波动力学均符合理想爆轰波理论, 并且与靶材原子拓扑结构无关. 两种合金靶在纳秒激光烧蚀中均承受显著的过热并最终发生爆炸沸腾. 爆炸沸腾在靶表面形成一种多层级烧蚀形貌: 由纳米孔洞 广泛分布的微米凹坑. 相比于晶态靶, 非晶合金靶呈现出较浅的凹坑以及较小的纳米孔洞. 这是由于非晶合金靶在激光烧蚀中具有 较浅的热影响区, 但过热程度较高. 进一步研究发现, 这种微纳多层级烧蚀形貌可有效调节两种合金靶的表面润湿性能, 从初始亲 水性改变为疏水性; 非晶和晶态靶的表面接触角分别提高约119%和64%. 本工作表明非晶合金对纳秒脉冲激光烧蚀具有更好的防 护性能, 并为非晶态或晶态合金的润湿性调节提供了一种可行且便捷的方法.