L. Lazov, N. Angelov, Physical model about laser impact on metals and alloys Contemporary Materials I−2 (2010) Page 124 of 128 Original scientific papers UDK 535.42:528.8.04 DOI: 10.5767/anurs.cmat.100102.en.114L PHYSICAL MODEL ABOUT LASER IMPACT ON METALS AND ALLOYS L. Lazov * , N. Angelov Technical University of Gabrovo, Hadzhi Dimitar 4, 5300 Gabrovo, Bulgaria Abstract: In this article we present our physical model for interaction of laser radia- tion with metals and alloys through structural changes, melting and vaporizing. We describe the interaction of laser radiation with materials, kinetic process of energy transmitting from free electrons to the crystal lattice and propagation of heat and the processing zone. We consider influence of optical and thermal properties over exploring process as they change with temperature and in the presence of mixtures. Keywords: physical model, laser, metals, alloys, characteristics. INTRODUCTION Laser marking is a technological process in which a number of mutual connected physical phe- nomena and effects participate, and with interaction of laser radiation with material. These processes are connected with each other in many cases, i.e. they interact with each other. In order to manage the qua- lity and the results of technology process, it is neces- sary to know these processes, as well as to know the principles connecting them. This knowledge is also necessary for successful monitoring of technological process in on-line regime and for selection of appro- priate device for creating of technological systems. Laser processing occurs in space and time and represents an impact of radiation on the material. Therefore, there is a need to explore the quantity of absorbed energy of laser radiation in substrate and its impact on the material. Figure 1 presents the prin- cipal scheme of energy balance of laser impact on metals and alloys. This gives us a notion of comple- xity of interaction of laser radiation with material and connections between these phenomena and pro- cesses [1]. As a result of interaction, electromagnetic energy is transformed in thermal energy. The effic- iency of the entire process is strongly impacted by the losses that are a result of scattering and reflect- ion. Only actually absorbed quantity has a direct i- mpact on the technology method and the result of the processing. It is clear that with regards to the te- chnological method of melting, vaporizing, or struct- ural changes in the material, only a part of that energy makes a real contribution, because the losses appear as a result of convection, heat radiation and thermal conductivity. Figure 1. Principal scheme of energy balance of laser impact over metals and alloys PRESENTATION We may examine the absorbed energy as a de- gree of efficiency η А of total laser energy that falls onto the material, i.e. that is a part of falling energy LASER ENERGY For technological process Structural changes Melting Vaporization Interaction of laser radiation Atmosphere Covering Sample Absorbed laser energy Dissipation Reflection Useful energy Losses Convection Thermal radiation Conduction * Corresponding author: llazov@abv.bg