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

Abstract

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 865-893 K and activation energies, 470 kJ/mol, are measured in the multilayers exhibiting the TE. The onset temperature is increased by 60-80 K 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.