Laser Gas Alloying

Abstract

Traditionally, laser surface alloying has been a two-step process in which an alloying element has been deposited onto the surface and subsequently laser melted into the substrate (1), The composition of such a layer is dependent on the thickness of the substrate melted. The homogeneity of the layer is ensured by long-range convection as well as short- range diffusion. It is also possible to alloy by heating the substrate in an apropriate atmosphere (2,3,4). Unless the surface is melted, there is very little alloying, as the rate of diffusion in the solid is low. The convection effect is then absent. If melting takes place, alloying over considerable distances becomes possible. The precise mechanism of absorption/desorption in each particular case differs depending on the nature of the gas-metal system. However, the behavior in general can be described by the fundamental law of mass action.