Material Flow Behavior and Microstructure Evolution During Direct Hot-Press Bonding of Ti/Mg Laminates with Interlocking Structure

Ti/Mg laminates, with an interlocking structure, which is characterized by prefabricated holes, are prepared by direct hot pressing. Reasonable process parameters including temperature, reduction, and interval between prefabricated holes are established. The reasonable temperature range is 350−400 °C, and reduction should be at least 47% at 375 °C. While filling single holes, shearing zones composed of fine-grained bands form throughout the magnesium layer. Their formation can be divided into three stages including the refinement of original coarse grains, preferential recrystallization of the local area, and expansion of fine-grained bands. Coarse grains that remain in the fine-grained band do not fully recrystallize due to the activation of the single slip system. The filling process of adjacent holes is mutually affected. A lamellar heterogeneous structure forms in the magnesium layer, composed of coarse-grained layers at the top and the bottom and fine-grained layer in the middle. The Fine-grained layer is more homogeneous in microstructure, when the interval reaches 9 mm, indicating that the optimum interval is 9 mm. Ti/Mg laminates with multiholes are acquired and a swallow-tailed interlock structure is formed. The fracture load reaches 2.12 kN with prefabricated holes, which is 16.5% higher than that without prefabricated holes.