MONTE-CARLO SIMULATION OF NONEQUILIBRIUM SEGREGATION DURING CRYSTAL-GROWTH

Ising model simulations of the crystallization of two component mixtur es have been performed for crystallization conditions both near and fa r from equilibrium. These simulations reproduce the phenomenon which h as been termed 'solute trapping', where rapid crystallization results in crystals with concentrations which are far from equilibrium concent rations. Thermodynamic properties of Si doped with Bi have been used a s a model alloy system in the simulations because there are extensive experimental results for these alloys. Simulations predict that crysta llization far from equilibrium follows quite different rules from crys tallization near equilibrium. This has significant implications for al l first order phase changes in mixtures which take place under conditi ons which are far from equilibrium. (C) 1997 Published by Elsevier Sci ence B.V.