Abrupt transition from wavelength structure to subwavelength structure in a single-crystal superalloy induced by femtosecond laser

• Published in: Applied surface science 2011-02, Vol.257 (9), p.4321-4324
• Main Authors: Zhang, Wei, Cheng, Guanghua, Feng, Qiang, Cao, Lamei, Wang, Fengping, Hui, Rongqing
• Format: Article
• Language: English
• Subjects: Abrupt transition; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Femtosecond; Femtosecond laser; Grooves; Lasers; Microstructure; Nickel base alloys; Physics; Ridges; Ripples; Second harmonic generation; Superalloys; Wavelengths
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2010.12.050

▶ Transition from wavelength structure (LSFL) to subwavelength structure (HSFL). ▶ Transition is initiated by generation of new grooves on main ridges of LSFL ripples. ▶ Relationship between structures and their parametric dependence is established. ▶ Second harmonic generation is responsible for the formation of HSFL. The abrupt transition from low-spatial-frequency laser-induced periodic surface structure (LSFL) to high-spatial-frequency laser-induced periodic surface structure (HSFL) in single-crystal superalloy CMSX-4 during femtosecond laser irradiation has been reported. Microstructural investigations indicate that the transition was initiated by the generation of new grooves on the main ridges of LSFL ripples. This transition resulted in the period of HSFL nearly equal to half of LSFL period. Furthermore, the relationship between both LSFL and HSFL and their parametric dependence was established. The microstructural observation of the abrupt transition provides a morphological evidence of second harmonic generation being responsible for the formation of HSFL.