Periodic and uniform nanogratings formed on cemented carbide by femtosecond laser scanning

SEM images of the nanogratings formed on the surface of YS8 cemented carbide by femtosecond laser pulses with different single pulse energies, (a) 2.75 μJ, (b) 2.5 μJ, (c) 2.25 μJ, (d) 2 μJ, (e) 1.75 μJ, and (f) EDX composition analysis in the selected area point 1 of (a). P denotes the orientation of the laser beam polarization. S denotes the orientation of the laser scanning. (Scanning speed V = 500 μm/s, scanning spacing D = 5 μm).