The mechanism of eutectic growth in highly anisotropic materials

In the past 50 years, there has been increasing interest—both theoretically and experimentally—in the problem of pattern formation of a moving boundary, such as a solidification front. One example of pattern formation is that of irregular eutectic solidification, in which the solid–liquid interface is non-isothermal and the interphase spacing varies in ways that are poorly understood. Here, we identify the growth mode of irregular eutectics, using reconstructions from four-dimensional (that is, time and space resolved) X-ray microtomography. Our results show that the eutectic growth process can be markedly different from that seen in previously used model systems and theories based on the ex situ analysis of microstructure. In light of our experimental findings, we present a coherent growth model of irregular eutectic solidification.