强脉冲激光在AZ31B镁合金中诱导冲击波的实验研究

Experimental study of shock waves induced by high-power pulsed laser in AZ31B magnesium alloy

为了研究强脉冲激光在镁合金中诱导冲击波的衰减,采用Nd:Glass脉冲激光(1054nm,23ns)对AZ31B变形镁合金试样表面进行冲击,并利用响应快、测量范围大的PVDF压电膜传感器以及示波器实时测量了强脉冲激光在镁合金靶中诱导激光冲击波的相对压力.根据冲击波每次在靶材背面反射时,所经过距离的不同得到激光冲击波在镁合金中的衰减规律.结果表明,在激光能量为5J的强脉冲激光作用下,镁合金中冲击波衰减的平均速度为5.83×103m/s,与镁合金中应力波纵波的传播速度相符;强脉冲激光诱导冲击波在镁合金中是以指数规律衰减的.试验所得分析结果对激光冲击强化镁合金的应用具有重要意义.

In order to study the attenuation of shock waves induced by a high-power pulsed laser in magnesium alloy,an AZ31B magnesium alloy sample is processed with an Nd：Glass laser with a wavelength of 1054 nm and pulse width of 23 ns,and the relative pressures of the shock waves are measured on time by a polyvinglidene fluoride （ PVDF） gauge with a short rise time and a wide linear response range,combined together with an oscilloscope. The law of attenuation of laser shock wave is obtained by measuring the intensity pressures on the rear surface of the target for different thicknesses through which the shock waves pass each time. The experimental results show that the average velocity of the shock wave attenuation in magnesium alloy is 5. 83 × 103 m /s with using a laser pulsed energy of 5 J is in good agreement with the propagation velocity of stress longitudinal wave; the law of the shock wave attenuation is exponential. The experimental result can be very useful for the laser shock processing on magnesium alloy.