Research On The Preparation Of Reactive Multilayer Foils And Combustion Synthesis

Combustion synthesis is a rapid, high-temperature, efficient, and energy-savingreaction. As the theory of combustion synthesis, the reactive multilayer foils, preparedby kinds of methods and using the energy generated by the combustion synthesis, canbe applied to join different materials as the inter-media material for joining. Comparedwith conventional soldering and brazing techniques, the reactive multilayer foilshave the advantages of high temperature, rapid reaction, elimination of any externalheat sources, and energy saving, so it has great potential for application.In this article, the reactive multilayer foils with kinds of systems wereprepared by the rolled method, which is a simple, efficient, and low-costtechnique. The combustion synthesis properties and the effects of thepreparation procedures on the properties of the reactive multilayer foils havebeen studied. The Al3Ni reactive multilayer foils were achieved by rolling thestacked raw materials of Al and Ni sheet foil with the atomic ratio3:1. Theforming mechanism of the multilayer by rolling has been studied and it wasfound that the harder Ni sheet foils break into long particles embedded in Almatrix after rolling passes so as to make the Al and Ni foils mixed and joinedtogether as a uniform multilayer. The effects of the preparation procedures onthe macro forming properties and the combustion synthesis properties have alsobeen analyzed to optimizing the rolling procedures and to improve theproperties of the reactive multilayer foils. The rolling temperature wasintroduced into the rolling procedure to increase the deformation of the Al andNi, so it improved the macro forming properties obviously. However, it led tothe increase of the Ni particle size, and the decrease of mix homogeneity, so itworsened the combustion synthesis. To improve the combustion synthesis ofreactive multilayer foils, the Al and Ni sheet foil with atomic ratio1:1and highadiabatic temperature, were introduced to prepare the AlNi reactive multilayerfoils by the optimized rolling procedures. The phase transformation of AlNireactive multilayer foils’ combustion synthesis was studied by the quenchingtechnique. According to the microstructure and phase characteristic, the combustion synthesis can be observed as a two-stage reaction. During the firststage, the nucleation of Al-rich phase forms followed by the coalescence of theAl-rich grains. And then the Al-rich phase reacts with Ni and continues to growuntil the formation of final product of AlNi phase, emitting a strong white light.In order to develop the application potential and improve the properties ofnew reactive multilayer foils system, the Al foil/Ni powder reactive multilayerfoils was achieved. The added Ni powder improved the forming property and themix homogeneity of Al and Ni obviously, but the stacking problem of Al foilwith Ni powder needs to be improved. Finally, the AlTi reactive multilayer foilswere prepared by cold rolling with the raw materials of Al and Ti sheet foil. Thecombustion synthesis could not be ignited because of the bigger particle size ofTi and the decrease of the mix homogeneity of Al and Ti.