Modelling of transport phenomena in laser surface alloying with distributed species mass source

In this paper, a three-dimensional transient macroscopic numerical model is developed for the description of transport phenomena during laser surface alloying. In order to make accurate estimates for the species composition distribution during the process, the addition of alloying elements is formulated by devising a species generation term for the solute transport equation. By employing a particle-tracking algorithm and a simultaneous particle-melting consideration, the species source term is estimated by the amount of fusion of a spherical particle as it passes through a particular control volume. Numerical simulations are performed for two cases. The first case corresponds to aluminium as alloying element on a nickel substrate, while the second case is for alloying nickel on aluminium substrate. It is observed for the latter case that the melting of the alloying element is not instantaneous, and hence it cannot be modelled as a species mass flux boundary condition at the top surface. The predicted results are compared with experiments, and the agreement is found to be good.