Ta/Ti/Ni/Ceramic Multilayered Composites by Combustion Synthesis: Microstructure and Mechanical Properties

Ta/Ti/Ni/ceramic multilayered composites were successfully prepared by combustion synthesis. Laminated composites Ti-Ta-(Ti + 0.65C)-Ni-(Ti + 1.7B)-(Ti + 1.7B)-Ta-Ni-Ti and 3(Ti + 1.7B)-Ta-(5Ti + 3Si)-Ta-(Ti + 1.7B)-Ta-(5Ti + 3Si)-Ta-3(Ti + 1.7B) were combustion synthesized in an Ar atmosphere using (1) metallic foils (Ti, Ta, Ni) and (2) reactive tapes (Ti + 0.65C), (Ti + 1.7B), and (5Ti + 3Si), which, upon combustion, yielded ceramic layers as starting materials. The microstructure, crystal structure, and chemical composition of multilayered composites were characterized by SEM, EDX, and XRD. Their flexural strength was measured at 1100 degrees C. Upon combustion, Ta foils turned strongly joined with Ti ones due to the development of high temperature in the reactive layers yielding TiCx and TiBy. The formation of a liquid phase between metallic foils and reactive tapes and mutual interdiffusion between melted components during combustion favored strong joining between refractory metallic foils. Good joining between metals and ceramics is reached due to the formation of thin interfacial layers in the form of cermets and eutectic solutions.