# Fabrication of Smart Materials Using Laser Processing: Analysis and Prospects
## 2 Laser Modification for Smart Materials  
Laser modification is a powerful technique employed to modify the physical and chemical properties of materials, offering a wide array of applications and the ability to create smart and intelligent materials [50]. By utilizing a laser beam, the material's surface can be heated or melted, enabling precise changes in its structure and properties [51; 52]. This can involve the creation of micro- and nanostructures on the material's surface, influencing its mechanical, optical, or electronic characteristics [53]. One of the notable features of laser material modification is the precise control of laser parameters, such as power, pulse duration, and frequency, allowing for fine-tuned material changes. As a result of laser modification, a material's properties can be tailored to specific tasks. This may include enhancing mechanical strength, improving adhesion to other materials, modifying optical characteristics, and even achieving superhydrophobic and self-cleaning surface properties [54; 55; 56]. To create smart materials, laser modification can be carried out in several ways. Laser shock treatment is used to form gradient nanostructures in the surface layer, which is one of the methods of surface intensive plastic deformation under extreme conditions [57; 58]. Laser hardening selectively heats the material's surface to enhance its hardness and wear resistance, resulting in smart materials with improved durability and resistance to wear and tear [59; 60; 61]. Typically, this process enables the transformation of only the near-surface layer, but in the case of thin elements, it is feasible to harden the entire depth of the material [62]. To optimize the laser hardening process of a thin-walled medium manganese steel sample using oscillating beam technology, a simulation was conducted. The simulation involved defining the power distribution and virtually determining the oscillation frequency. This approach successfully led to the modification of the shape of the hardened zone during the experimental laser hardening process using a disc solid-state laser beam source, applying a power level of 1200 W (Figure 1). The laser hardening process for medium and high-carbon steels entails locally raising the temperature and then self-quenching at rapid cooling due to the high thermal conductivity of the metal, leading to the formation of a martensitic microstructure with greater hardness compared to the original ferrite-perlite microstructure. In [63], laser surface hardening of AISI 420 steel was carried out using a diode laser with a wavelength of 1064 nm. The processing that was aimed at the formation of a hardened surface with slight melting was performed at 480 W power and scanning speed of 20 mm/s; the size of the laser spot with a top-hat profile was 3 mm. In Figure 2, the microstructure of the cross-section of the laser-hardened AISI 420 steel, examined using a stereo microscope, is displayed. The melt pool had a depth of approximately 370 \(\upmu\)m, and each track measured about 2100 \(\upmu\)m in width, with slight overlapping. The geometry of the melt pool is related to the process of heat input, which is influenced by laser power and scanning speed. The modification of these parameters affect the hardening depth. Thus, increasing the laser power or decreasing the scanning speed leads to an increase in the hardening depth. Laser alloying involves melting a thin near-surface layer of the material and introducing alloying elements or compounds, imparting unique properties such as enhanced corrosion resistance and electrical conductivity [64; 65; 66]. Laser bording of martensitic aging steels has proven to be highly effective in increasing wear resistance. The study in [67] demonstrates that changing laser irradiation parameters, such as laser beam energy and scanning speed, influences the bording process results in a variety of microstructures in the obtained boronized layers.