光学学报, 2010, 30 (9): 2613, 网络出版: 2014-05-15
脉冲激光冲击镁合金表面产生周期性波纹结构的现象及分析
Phenomenon and Analysis of Periodic Ripple Structure on Magnesium Alloy Surface Induced by Laser Shock Processing
激光光学 激光冲击处理 表面波纹 冲击波波阵面 等离子体 laser optics laser shock processing(LSP) surface ripple shock wave front plasma
摘要
为了研究激光辐照材料引起表面波纹现象及原因,采用钕玻璃激光器产生的脉冲激光来冲击黑漆作为吸收层的AZ91镁合金试样。激光冲击后采用表面三维轮廓仪对试样冲击区域表面进行测量,结果得到在冲击区域存在波纹分布现象;观测并描绘了表面形貌及表面波纹的分布情况,并分析了材料表面波纹特性与激光能量的关系;得出波纹特性受激光能量影响。最后从等离子体对试样的作用和等离子体内部相干受激光散射机制引起的光栅效应两个方面出发,讨论了热传导、热辐射以及激光照射等因素在试样表面产生热微扰动现象的耦合过程,进而从表面热微扰动的非平衡状态探讨了表面波纹的形成机理。
Abstract
In order to study the ripple phenomena and its causing mechanism on material surface that caused by the laser irradiation, the pulse generated by neodymium glass laser was used to shock the specimen of magnesium alloy AZ91 covered with black paint as the absorption layer. The threedimensional surface measurement instrument is applied to measure the shocked region of the specimen surface after shocking. And the ripples phenomenon is observed in the shocked region from the measurement results. The surface morphology, as well as the distribution of the surface ripples, is observed and described; and the relation between the characteristics of the ripples and the laser energy is analyzed. It can be concluded that the characteristics of the ripples are affected by laser energy. Based on the effects of the plasma to the specimen and the grating effects caused by the mechanism of coherent stimulated light scattering within plasma, the process of generating thermal microdisturbance on the sample surface by coupling the thermal conductivity, the thermal radiation and the laser irradiation is discussed, and then the formation mechanism of the surface ripples caused by the nonequilibrium state of the surface thermal microdisturbance is discussed.
张永康, 裴旭, 陈菊芳, 顾永玉, 任爱国, 尤建. 脉冲激光冲击镁合金表面产生周期性波纹结构的现象及分析[J]. 光学学报, 2010, 30(9): 2613. Zhang Yongkang, Pei Xu, Chen Jufang, Gu Yongyu, Ren Aiguo, You Jian. Phenomenon and Analysis of Periodic Ripple Structure on Magnesium Alloy Surface Induced by Laser Shock Processing[J]. Acta Optica Sinica, 2010, 30(9): 2613.