Microstructure and Phase Selection in Laser Treatment of Materials

Abstract

Microstructure formation during the laser treatment of materials is discussed so as to enable one to design appropriate alloys and laser processing conditions which will produce a microstructure that has optimum properties. In order to predict microstructures for different laser processing conditions, the theoretical models for single phase and two-phase eutectic growth under a wide range of solidification rates have been developed. Specific emphasis is placed on the new physics that become important under rapid solidification conditions of laser processing. Based on these models, the selection of a specific microstructure under given laser processing conditions has been established. These results are then used to construct microstructure/ processing condition maps for the laser treatment of materials. These diagrams theoretically predict the variation in the microstructure along the depth of the solidified pool as a function of laser scanning velocity.