采用脉冲宽度为100 ns和2.1 ps激光对厚度为0.8 mm DD6镍基单晶合金进行了表面烧蚀、加工小孔等实验。观察不同脉冲能量下材料的烧蚀形貌和直径,得到了DD6镍基单晶合金等效脉冲数为670时纳秒和皮秒激光的烧蚀阈值。对纳秒和皮秒激光烧蚀凹槽剖面进行金相观察,以确定两种激光烧蚀材料的区别。在相同能量密度条件下,纳秒和皮秒激光制孔,观察孔表面和孔壁质量。实验结果表明,纳秒激光和皮秒激光对DD6镍基单晶合金的烧蚀阈值分别为1.63、0.11 J/cm2;纳秒激光烧蚀凹槽内充满再铸层和微裂纹等热缺陷,而皮秒激光烧蚀凹槽内无再铸层且边缘材料的显微组织无任何变化;纳秒激光制孔表面存在飞溅物,孔口堆积冠状熔化物,孔壁存在微裂纹和20 μm厚的连续再铸层,皮秒激光制孔,孔表面基本无飞溅物,孔壁上存在微裂纹和间断的再铸层,孔口较圆整。

The DD6nickel-based single-crystal alloy film with a thickness of 0.8 mm is ablated and drilled in nanosecond(100 ns)and picosecond(2.1 ps)lasers. The 670 equivalent pulses ablation threshold of DD6in the above both lasers is obtained, based on observing ablation surface appearance and ablation area in different laser energy. The metallographic phases of the groove ablated by nanosecond and picosecond laser are researched in detail to observe the difference of the ablation by nanosecondand picosecond laser. While setting the fluence as 22 J/cm2, the micro-holes whose diameter is 400 μm are drilled in the DD6 film, then the surface and wall quality of the hole are researched. Experimental results demonstrate that the ablation threshold of DD6 in the nanosecond and picosecond laser are1.63J/cm2 and 0.11 J/cm2 separately. The groove ablated by nanosecond laser is full of micro cracks and continuous recast layer. But there is no heat affect edzone in the groove ablated by picosecond laser whose metallographic phase is not changed too. There are spatters and coronary melted material surrounding the micro-hole drilled by nanosecond laser, while some micro cracks and recast layer with thickness of 20μm appear in the wall of micro-hole. There is nearly no spatter on the surface of the micro-hole and there are some micro crack and discontinuous recast layer in the wall of micro-holes. And the shape of the hole is round.