MICROSTRUCTURES AND MECHANICAL PROPERTIES OF TiAl/Ti3Al MULTI- LAYERED COMPOSITE

In recent years, intennetallic compounds have received a lot of considerable attentions for high temperature applications in modem aircraft manufacturers, high temperature engine components, shape memory devices and power generation industry. Among these materials, Ti-Al intermetallic compounds are fascinating materials owing to their low density, high stiffness and good creep properties. However, the structure of the metallic bonding in these intermetallics is the important reason for their insufficient ductility at room temperature. In this work, large-sized TiAl/Ti3Al multi-layered composite thin sheet with uniform chemical composition was prepared by electron beam physical vapor deposition (EB-PVD) technology. The composite and microstructure of multi-layered composite were analyzed by XRD and SEM. The results indicated that the prepared material with visible lamellar structure was composed of alpha(2)-Ti(3)A1 and gamma-TiAl phases. The densification process of composite was carried out by hot isostatic pressing. The multi-layered material was evaluated with static tensile test before and after hot isostatic pressing. The multi-layered composite after hot isostatic pressing had a higher tensile strength and a good characteristic of tensile elongation. Based on the tensile fracture morphology, the microscopic deformation mechanisms and fracture mechanism were investigated. After hot isostatic pressing, the fracture mechanism transforms to a mixed mode which consists of intergranular fracture and cleavage fracture.