Distribution of α-, β-, and γ-Phases in a Multi-flow Injection-molded Hierarchical Structure

In the current work, a custom-made vibration injection molding device that can provide oscillatory pressure was utilized to create an injection-molded hierarchical structure. Growth competition among alpha, beta, and gamma phases in the injection-molded structure can be studied because of the presence of this hierarchical structure, wherein shish-kebab and spherulite layers were arranged alternately along the thickness direction. The gamma crystals only existed in layers subjected to high pressure and shear stress, whereas beta crystals formed between the shear layers. The change in trend of the gamma fraction was similar to that of parent-to-daughter ratio. In addition, this hierarchical and alternating crystal structure can sharply increase the mechanical properties.