Microstructure, mechanical properties and formability of Ti/Al/Ti laminated composites fabricated by hot-pressing

摘要

Ti/Al/Ti laminated composites (LMCs) with different interfacial bonding strength were prepared by hot-pressing at different temperatures. The effects of interfacial morphology, reaction layer and constraint effect on the microstructure, mechanical property and formability of Ti/Al/Ti laminated composites were explored. The results indicate that micron-scale TiAl3 phases are formed at the interface. The degree of curve, the bonding strength and the micro-hardness at the interface all increase with the increasing hot-pressing temperatures. However, both the strength and elongation of laminated composites reduce with the increase of temperature. The reduction of the strength is attributed to the shear fracture tendency at the curved interface and the softening effect at high temperature, while the change of elongation is related to the interfacial debonding and constraint effect. The variation of stretch formability is nonlinear with the increase of hot-pressing temperature, which is related to the crack initiation and propagation behaviors during forming. The LMCs possess excellent ductility and Erichsen values at lower temperature, which results from the increased damage tolerance and fracture absorption energy caused by the local interfacial debonding. Nevertheless, the LMCs exhibit complex mechanical behavior at higher temperature due to two competition mechanisms: coordinated deformation by stress-strain transfer under a strong constraint and unmatched deformation by the intermetallic at the interface.