Effect of the chemical composition of multilayer Ni/Al foil on its deformation behaviour during heating under load

Multilayer foils (MFs) derived from reaction systems such as Ni/Al are promising interlayers for forming permanent joints by soldering or diffusion bonding. To obtain soldered joints in the MF, a self-propagating high-temperature synthesis (SHS) reaction is initiated. During diffusion bonding, the reaction-diffusion in the MF is controlled by external heating of the joint zone, thereby reducing heat generation there. The authors of many works showed that, in addition to the MF effect on diffusion processes in the welded zone, there is a correlation between the deformation behaviour of MFs and joint-process parameters. In this work, the impact of the chemical composition of the MF on its deformation behaviour during heating under constant load conditions was investigated using the Ni/Al MF with component ratios of 1:3, 1:1, and 3:1, corresponding to the intermetallics Al 3 Ni, AlNi, and AlNi 3 , respectively. It was shown that the deformation behaviour of MFs changes drastically with an increase in the nickel content from 1:3 to 3:1, due to the activation of various plastic deformation mechanisms. It turns out that the monotonic increase in the rate of plastic deformation upon heating of MF with a ratio of 1:3 is due to its superplastic flow by the mechanism of intergranular slip. The non-monotonic temperature dependence of the rate of deformation of MF with a ratio of 1:1 or 3:1 is realised by both the mechanism of intergranular slip and superplastic flow due to phase transformations that occur only within certain temperature intervals.