Mass transport in laser surface alloying: Iron-nickel system

Abstract

The role of fluid flow in producing uniformly alloyed beads in laser surface alloying is examined and the experimental finding that the uniformity of alloying increased with a decrease in the beam diameter is analyzed. Fluid flow can dominate the process of solute redistribution in the melt pool by producing a fine dispersion of solute rich pockets. The fineness of the scale is estimated and found to compare favorably with the experimentally measured scale of local fluctuations in composition. It is found that the magnitude of the surface tension gradients is primarily dependent upon the magnitude of the surface temperature gradients. This can be used to estimate the effect of process parameters on the vigor of the fluid flow in the pool, which controls the process of mass transport in laser surface alloying.