In-situ Fabrication and Fracture Characteristics of Structural Gradient Ni/Ni-aluminide//Ti/Ti-aluminide Layered Materials

摘要

Ni/Ni-alumimde//Ti/Ti-aluminide laminate composite, considered as a functionally gradient material, was manufactured by thin foil hot press technique. Thick intermetallic layers of NiAl and TiAl_3 were formed by a self-propagating high-temperature synthesis (SHS) reaction, and thin continuous layers of Ni_3Al and TiAl were formed by a solid-state diffusion. Fracture resistance with loading along the crack arrester direction is higher than crack divider direction due to the interruption of crack growth in metal layers. The Ni_3Al and NiAl intermetallic layer showed cleavage and intergranular fracture behavior, respectively, while the fracture mode of TiAl_3 layer was found to be a intragranular cleavage. The debonding between metal and intermetallic layer and the pores were observed in the Ni/Ni-aluminide layers, resulting in the lower fracture resistance.