Limit of steady-state lamellar eutectic growth

Under rapid solidification conditions, a eutectic microstructure becomes unstable beyond a certain velocity that places a limit on the finest spacing and the largest interface undercooling that can be achieved for such a microstructure. Expressions are developed to characterize the physics that lead to the limit of eutectic growth. Activation energy for diffusion and eutectic temperature are shown to play key roles at the limit of eutectic growth, and this limit modifies the high-velocity branch of the coupled growth regime.

► Under rapid solidification, no steady state eutectic growth can occur beyond a certain growth rate. The conditions at the limit of eutectic growth are developed in this paper.
► It is shown that the largest undercooling that can be obtained for eutectic growth is a function of activation energy for diffusion and the eutectic temperature only, and it does not depend on other system parameters.
► The maximum undercooling for eutectic growth is shown to influence the coupled growth regime.