Approaching non-destructive surface chemical analysis of CMSX-4 superalloy with double-pulsed laser induced breakdown spectroscopy

Laser induced breakdown spectroscopy (LIBS) was performed on the CMSX-4 Ni-based superalloy using a femtosecond pulsed laser. An orthogonal double-pulse technique was used to minimize surface damage associated with LIBS. With this technique, the depth of ablation craters was reduced from 200 nm for single-pulse LIBS down to less than 60 nm using orthogonal double-pulse LIBS. The technique also allowed the average velocity of the ablated material to be determined, which ranged from 4720 ± 560 m/s at a pump laser fluence of 3.1 J/cm2 to 8150 ±1800 m/s at 10.1 J/cm2.