Mechanical properties measurements on alumina/aluminum nanolaminates

Nowadays, the characterisation of thin films is very important for all kinds of applications, in electronics or coating. This research work is carried out with the aim of determining the mechanical properties of nanolaminates composed of alumina and aluminium. To this end, nanoindentation tests are carried out in the first instance, but also Lab On-Chip tests (LOC), a technique developed by UCLouvain, and tensile tests on polymer. First, a Young's modulus of 145 GPa and a hardness of 7.5 GPa are found, but also variations in Young's modulus and hardness as a function of the strain rate showing a viscoelastic and viscoplastic character. Continuous stiffness measurements at different strain rates are used to obtain a strain rate sensitivity coefficient of 0.04 at higher strain rates and Paul Baral's method is used for the strain rate sensitivity coefficient of 0.24 at lower strain rates. A strain up to 3.4 % is achieved using the lab on-chip technique and even up to 4.7 % after some relaxation. Plastic strain is reached. Relaxation of the material also allows to determine a strain rate sensitivity coefficient between 0.01 and 0.03. Finally, nanoindentation deforms plastically the nanolaminate while the LOC tests seem to show a brittle fracture and the tensile tests on polymer give very sharp cracks with a rapid propagation.