Interaction of Long Time Pulses of an Nd³⁺:YAG Laser Beam with the Heusler AlloyNi₄₅Co₅Mn_35.5In_14.5

In this paper, the laser processing of the surface of bulk and layered samples (of thickness 75 nm) of Ni₄₅Co₅Mn_35.5In_14.5 alloy (NC5MI) was investigated using microsecond laser pulses. A Q-switched pulsed Nd³⁺:YAG laser, operating in the 1st harmonic (which had a wavelength of 1064 nm) with a pulse duration of 250 µs, was used. NC5MI is a metal resistant to thermal laser processing because its reflection coefficient is close to unity for long wavelengths. The aim of this paper was to learn the forms of laser processing (heating, microprocessing, ablation) for which the above-specified type of laser is useful. The samples were irradiated with various fluences in the interval of 5-32 J·cm^-2. The effect of the laser interaction with the surface was explored by SEM microscopy. The threshold fluences for the bulk sample were determined as: the visible damage threshold (F_th^d = 2 ± 0.2 J·cm^-2), the melting threshold (F_th^m = 10 ± 0.5 J·cm^-2), and the deep melting threshold (F_th^dm = 32 J·cm^-2). Unexpectedly, these values wereincreased for the layer sample due to its silicon substrate. We have concluded that this type of laser radiation is advantageous for the annealing and melting of, or drilling holes in, the alloy, but disadvantageousto the ablation of the alloy.