Abstract (EN):
Ni/Al multilayers are known to transform into NiAl in a highly exothermic and self-sustaining reaction. The fact that this reaction has a high heat release rate and can be triggered by an external impulse, are reasons why it has already attracted much research attention. There is a huge potential in the use of Ni/Al multilayers as a controllable and localized heat source for joining temperature-sensitive materials such as microelectronic components. The heat released and the phases resulting from the reaction of Ni and Al multilayers depend on the production methods, their composition, as well as the bilayer thickness and annealing conditions. The present research aims to explore the influence of these variables on the reaction of different multilayers, namely those produced by accumulative roll bonding (ARB) and sputtering. Structural evolution of Ni/Al multilayers with temperature was studied by differential scanning calorimetry, x-ray diffraction and scanning electron microscopy. Phase evolution, heat release rate and NiAl final grain size are controlled by the ignition method used to trigger the reaction of Ni and Al. The potential use of these multilayers in the diffusion bonding of TiAl was analyzed. The ARB multilayers allow the production of joints with higher strength than the joints produced with commercial multilayers (NanoFoilA (R)) produced by sputtering. However, the formation of brittle intermetallic phases (Ni3Al, Ni2Al3 and NiAl3) compromises the mechanical properties of the joint.
Idioma:
Inglês
Tipo (Avaliação Docente):
Científica
Nº de páginas:
8