超短脉冲激光诱导单晶铜熔化的物理机制

 采用校正的分子动力学方法研究了超短脉冲熔化单晶铜的动力学微观机制，建模时将熔化潜热的消耗及自由电子的热传导均考虑在内，使熔化过程的模拟更加真实。皮秒激光熔化单晶铜是一种过热熔化，可归因于液相在固相中的均匀形核。熔沿传播的速度高达5.8 nm/ps ，高于铜中声速。熔化发生在热约束区域内部，导致温度分布不太复杂，且卸载波对应力波的影响与应力约束区域相比较弱。

Physical mechanisms of ultrashort pulse laser induced melting in copper

The kinetics and microscopic mechanisms of ultrashort laser melting of a copper film is studied by modified molecular dynamics method.A model considering the thermal conductivity of free electrons and the consumption of latent heat of melting is used to make the simulation more realistic.The mechanism responsible for the melting of copper under picosecond laser pulse irradiation can be attributed to the homogeneous nuclea-tion of the liquid phase inside the solid region.The melting is a overheated melting caused by homogeneous nu-cleation.and the velocity of propagation of"melt front"is found up to be 5.8 nm/ps.Picosecond laser pulse in-duced melting occurring under the condition of thermal confinement results in a less complicate temperature dis-tribution and a weaker effect of unloading wave on stress wave compared with those in stress confinement re-gion.