纳秒激光加工中脉冲能量对熔体体积的影响

Effects of Pulse Energy on Melt Volume in Nanosecond Pulsed Laser Processing

目的考察调节激光脉冲能量对纳秒激光加工中熔体体积控制的途径。方法通过纳秒激光加工实验中的微结构火山口相对高度随脉冲能量的变化规律,来间接反映熔体体积随脉冲能量的变化规律。在MATLAB环境下,通过有限元法基于双温模型模拟,研究纳秒激光脉冲作用于铝合金材料表面时脉冲能量对熔体体积的影响规律。结果在低能量密度下,可实现低于10%的火山口相对高度,远低于文献记载的高能量密度下~100%的火山口相对高度。随着激光脉冲能量的增加,模拟结果和实验结果都表明熔体体积随能量密度的增加而略有减少,这与文献模型相悖。结论在较宽的能量范围内,纳秒激光加工产生的熔体体积随激光脉冲能量密度的变化规律符合C Korner等人提出的模型,表明通过控制激光能量密度能够有效控制纳秒激光加工中的熔体体积。然而,在较低的能量密度下,熔体体积随能量密度反常变化规律意味着有其他因素伴随能量密度共同影响熔体体积,这种影响还有待进一步研究。

The work aims to investigate the way of controlling melt volume in nanosecond laser processing by regulating the laser pulse energy. The variation of melt volume with pulse energy was reflected through the variation of the relative height of the microstructure crater in nanosecond laser processing experiment with the pulse energy. In MATLAB environment, the finite element method based on the double temperature model simulation was used to study the effect of pulse energy on the melt volume when the nanosecond laser pulse was applied on the surface of aluminum alloy material. At low energy density, the relative height of the crater below 10% could be achieved, which was much lower than the relative height of the crater of ~100% under high energy density recorded in the literature. At low energy density, with the increase of laser pulse energy, the simulation results and experimental results showed that the melt volume decreased slightly with the increase of energy density, which was contrary to the model in the literature. In the wider energy range, the melt volume produced by nanosecond laser processing conforms to the model proposed by C K?rner et al, which shows that the melt volume in nanosecond laser processing can be controlled effectively by controlling the laser energy density. However, the abnormal variation of melt volume with energy density at lower energy density means that there are other factors that accompany this energy density to affect melt volume together, and this effect has yet to be further studied.