Effects of the Al/Ni ratio on the reactions in the compression-bonded Ni-sputtered Al foil multilayer

The effects of the Al/Ni atomic ratio on the reactions of various Al/Ni multilayers are investigated. A compression-bonded Ni-sputtered Al foil multilayer process is proposed in order to study the phase formation and reaction heating in mechanically bonded multilayers. The compression-bonded multilayers exhibit advantages over the sputtered multilayers due to the negligible formation of an intermixed region and low process costs. Moreover, the process provides uniform and continuous layers that cold rolled foils cannot obtain. When the thermal annealing of Al/Ni is investigated using differential scanning calorimetry (DSC), the reaction paths differ significantly to the varying Al/Ni ratios. When the Ni/Al ratio of the multilayers was set to 3:1 and 3:2, the corresponding compounds (Al3Ni and Al3Ni2, respectively) were formed. Meanwhile, the reaction was not completed when sufficient Ni, above 40 at.%, was provided in the reaction. As the Ni atomic ratio increases from 41.2% to 57.6%, the reaction heating decreased from the theoretical values by up to 24.4%.