Analysis of monotectic growth: infinite diffusion in the L-2 phase

The Jackson-Hunt model of eutectic solidification is applied to monotectic solidification in which a liquid (L-1) transforms into rods of a different liquid (L-2) in a solid matrix. Limiting cases of no diffusion and infinite diffusion (complete mixing) in the L-2 phase are considered. An adaptive refinement and multigrid algorithm (MGGHAT) is used to obtain numerical solutions for the concentration field in the L-1 phase; this allows consideration of a general phase diagram. Density differences between the three phases, which cause fluid flow, are treated approximately. Specific calculations are carried out for aluminum-indium alloys. Infinite diffusion in the L-2 phase has only a small effect on the relationship between interface undercooling and rod spacing.