Laser surface nanoalloying of Fe, Si, and C on aluminum substrates with excellent optical and electronic properties

Abstract

Laser surface alloying of Fe, Si, and C on aluminium is demonstrated using a Q-switched Nd:YAG laser as the source of energy. The fundamental wavelength of the laser beam was 1064 nm with an output energy of 100 mJ and a pulse duration of 10 ns. The exposure was conducted in repetitive mode with a frequency rate of 1 Hz. The laser was focused to induce plasma formation. A pure aluminium plate was employed as the substrate to be alloyed. Iron (Fe) and ceramic material silicon carbide SiC were selected as the alloy elements. Two step deposition techniques were employed to predeposit the aluminium substrate. The substrate was painted with a cohesive material gum before powder spray coating on it. The predeposited aluminium was then exposed to a focused laser at various numbers of pulses (1–13 pulses). The resulting materials were examined via scanning electron microscopy (SEM), X-ray diffraction (XRD), and microhardness techniques, revealing the formation of a homogenized resolidified surface. The plasma temperature was much higher than the melting point of Fe and SiC, enabling an immediate interaction with coating materials. The different melting points of Fe, SiC, and Al allowed the formation of a new composite during quenching. The formation of such a new composite is identified via XRD analysis. Inherently, several new composites were revealed, such as Al–Fe–Si, SiAl, and Fe–Si, with enhanced mechanical strength. Apparently, the hardness of the modified surface is confirmed to be two times greater than that of the original substrate. The sensitivity of the MSM photodetector (PD) made of the resulting alloy is reasonably high and increases with increasing the bias voltage. The response times (T_Res) of the MSM PD for various numbers of laser pulses (1–13 pulses) were 0.60 s, 0.28 s, and 0.67 s with corresponding recovery times (T_Rec) of 0.53 s, 0.21 s, and 1.81 s, respectively.