Physics of the Effect of High-Temperature Pulse Heating On Defects in the Surface Layer of a Metal Alloy.

Selective laser processing of thin surface layers of metallic alloys selectively affects certain defective areas, such as stress concentrators, fracture nuclei, crack tips, and nanoscale particles. The rest of the material is practically unaffected. The method of selective laser processing increases both the microhardness and fracture toughness of, particularly, thin ribbons of hard and brittle amorphous- nanocrystalline metal alloys. It is essential that the initial amorphous-nanocrystalline structure of the material is preserved. The impact of a nanosecond laser pulse of high power density on the surface of a metal alloy is accompanied by laser-induced breakdown plasma, shock wave, and impulsive heating. The heating of the material is preceded by the passage of a compression shock wave capable of initiating local deformations and damages. The uneven heating of the material is primarily manifested in the defective areas and can lead to the relaxation of mechanical stresses due to plastic deformation. To study the interaction between the thermal front initiated by a laser pulse and defects in the surface layer of a metal alloy, it is necessary to improve the physical and mathematical models of these processes. [ABSTRACT FROM AUTHOR]