摘要

The interaction of Ti:sapphire laser, operating at high repetition rate of 75 MHz, with nickel-based super-alloy Inconel 600 was studied. The laser was emitting at 800 nm and ultrashort pulse duration was 160 fs. Nickel-based super-alloy surface modification was studied in a low laser energy/fluence regime of maximum 20 nJ-15 mJ/cm(2), for short (10 s) and long irradiation times (range of minutes). Surface damage threshold of this material was estimated to be 1.46 nJ, i.e., 0.001 J/cm(2) in air. The radiation absorbed from Ti:sapphire laser beam under these conditions generates at the surface a series of effects. such as direct material vaporization, plasma creation, formation of nano-structures and their larger aggregates, damage accumulation, etc. Laser induced surface morphological changes observed on Inconel 600 were: (1) intensive removal Of Surface material with crater like features; (2) material deposition at near and farther periphery and creation of nano-aggregates/nano-structures; (3) sporadic micro-cracking of the inner and outer damage area. Generally. features created on nickel-based super-alloy surface by high repetition rate femtosecond pulses are characterized by low inner/outer damage diameter of less than 11 mu m/30 mu m and relatively large depth on the order of 150 mu m, in both low (10 s) and high (minutes) irradiation time regimes.

  • 出版日期2009-12