毫秒激光致铝熔融液体准稳态喷溅的模型

通过对毫秒激光致铝(Al)熔融液体喷溅过程中 热通量的研究,建立了熔液在轴对称坐标下形成准稳态 喷溅的运动模型；进而通过解析和数值计算相结合的方法,得到了熔液准稳态喷溅过程中靶 材的中心点温 度、熔液表面的流动速率、熔池中心点的下降速度以及熔液喷溅后熔池的形貌。计算得到的 熔池中心点下 降速度随脉冲激光作用时间的增加而减小,熔液表面流动速率在准稳态喷溅时随熔池半径的 增加而增大。 计算得到的熔池形貌与实验结果相吻合,继而分析了毫秒激光致Al熔液准稳态喷溅时熔池中 心点温度和气 化区域半径随作用激光功率密度的变化关系。随作用激光功率密度的增加,更多的激光能量 转化为靶材的 内能,从而增加了熔液准稳态喷溅时熔池中心点的温度和气化区域半径。

A quasi-steady state model of liquid expulsion induced by millisecond pulsed laser

An axisymmetric quasi-steady state model of liquid expulsion induced by millisecond pulsed laser is built through the research of heat flux in the liquid ejection.The temp erature of central point,the flow velocity of molten liquid on quasi-steady state of liquid expulsion,the ablati on speed of central point and the molten pool shape are obtained by the analytic and numerical calculation.The des cend velocity of the central point on molten pool obtained from the calculation decreases with the time in mi llisecond pulse duration,and the decreasing rate reduces gradually.The liquid velocity o n molten pool surface in quai-steady state condition increases with the increasing radius of the molten pool,and the increasing rate reduces gradually.The shape of the molten pool after irradiating obtained from the calculation agrees with the experimental result,and then the dependences of temperature on central point and the radius of evaporation area on pulsed laser power density are discussed.With the increasin g power density of millisecond pulsed laser irradiated on the metal sample surface,more and more l aser pulse energy converts into heat of metal target.Then the temperature on central point of molten pool and radius of the evaporating area on liquid surface both increase.