Effect of Inserted Ti Layers on the Phase Transformation of Al/Ni Multilayer Foils

The thin Ti layers were inserted in the interfaces of base Al/Ni multilayer foils to form the Al/Ti/Ni/Ti (ATNT) foils through magnetron deposition. Al and Ni were determined in the as-deposited foils, while the absence of Ti was due to the strongly textured polycrystalline structure. TEM analysis implied an asymmetric interface structure between the Ni/Ti/Al interfaces and Al/Ti/Ni interfaces. After annealing at 473 K and 573 K for 3 h, the phase composition was the same as the initial state, which changed to be Al3Ni2, Ni3(AlTi), Ni and a small amount of Al3Ti when the treating temperature reached 673 K. Further increasing the annealing temperature to 773 K and 873 K leads to the appearance of stable AlNi. The obtained results implied that the inserted Ti layers impeded atomic interdiffusion and the formation of Al3Ni at the early stage, but had less impact on the final products. This further indicated that adding the inserted transition layer provides a reference to balance the storage stability and reaction performance of Al/Ni foils with regard to the applications.