The organization of materials determines their performance under specific conditions. To obtain the ideal material organization, controlling the crystallization process has become an important way to improve the performance of traditional materials and develop new materials. The theoretical study of directional solidification technology began in 1953, proposed by Charlmers and his colleagues. Since its inception, it has developed rapidly and is now widely used to obtain materials with special orientations and excellent performance. The emergence of directional solidification technology provides an important experimental basis for the research and development of solidification theory, as the two most critical parameters in the metal solidification process—temperature gradient and solidification rate—can be independently controlled during directional solidification. In addition, the directional solidification organization is very regular, which is convenient for accurately measuring its morphology and scale characteristics.