强激光辐照下纳米晶体铜薄膜层裂破坏的实验研究

Experimental studies of spallation in nanocrystalline copper film by laser irradiation

采用强激光辐照加载技术和激光速度干涉(VISAR)测试技术,对纳米晶体铜薄膜的层裂特性进行实验测量和分析.基于VISAR实测的自由面速度波形,计算得到纳米晶体铜薄膜在超高拉伸应变率下的层裂强度高达3GPa,明显高于多晶铜的层裂强度,其原因归咎于纳米晶体材料中存在大量晶界阻碍了位错运动.

The spall behavior of nanocrystalline copper film synthesized by electrodeposition technique is investigated by laser irradiation. The push-pull type VISAR with sub-nanosecond time resolution is used to measure the rear free surface velocity profile of the sample. The spall strength in nanocrystalline copper film is calculated from the measured free surface velocity profile as a function of tensile strain rate. Results show that the dynamic tensile strength of nanocrystalline copper film is about 3 GPa, which is much higher than that of polycrystalline bulk copper, but lower than that of single crystal copper. This difference may be attributed to the effective obstacles to dislocation motion by the presence or more grain boundaries in nanocrystalline copper.