Effects of interfacial Al oxide layers: Control of reaction behavior in micrometer-scale Al/Ni multilayers

Exothermic reaction behaviors of compression-bonded Al–Ni multilayers are investigated through controlling the interfacial layers of the multilayers. The native interfacial Al oxide layers between the Al/Ni bilayers are intentionally preserved to induce a thermal explosion (TE) during slow heating with up to a few tens of K/min. In contrast, the thermal annealing (TA) occurs in the highly shear-deformed multilayers with many broken Ni layers because the ductile Al fills the gaps in the broken Ni layers to form reactive Al/Ni interfaces. Increased onset temperatures of 865–893K and activation energies, 470kJ/mol, are measured in the multilayers exhibiting the TE. The onset temperature is increased by 60–80K over that of the multilayers exhibiting the TA. The influences of the interfacial native Al oxide layers that are preserved in order to delay the Al/Ni inter-diffusion on the exothermic reaction behavior of the compression-bonded multilayers are discussed.