Rapid multicomponent alloy solidification with allowance for the local nonequilibrium and cross-diffusion effects

Materials. 2023. Vol. 16. No. 4. Article 1622.

Sobolev S. L., Tokmachev M., Kolobov Y. R.

Abstract: Motivated by the fast development of various additive manufacturing technologies, we
consider a mathematical model of re-solidification of multicomponent metal alloys, which takes place
after ultrashort (femtosecond) pulse laser melting of a metal surface. The re-solidification occurs
under highly nonequilibrium conditions when solutes diffusion in the bulk liquid cannot be described
by the classical diffusion equation of parabolic type (Fick law) but is governed by diffusion equation
of hyperbolic type. In addition, the model takes into account diffusive interaction between different
solutes (nonzero off-diagonal terms of the diffusion matrix). Numerical simulations demonstrate
that there are three main re-solidification regimes, namely, purely diffusion-controlled with solute
partition at the interface, partly diffusion-controlled with weak partition, and purely diffusionless
and partitionless. The type of the regime governs the final composition of the re-solidified material,
and, hence, may serve as one of the main tools to design materials with desirable properties. This
implies that the model is expected to be useful in evaluating the most effective re-solidification regime
to guide the optimization of additive manufacturing processing parameters and alloys design.

Keywords: mathematical modeling, numerical calculations, metallic alloys, multi-component diffusion, ternary systems