Plastic behaviour of high-strength lightweight Al/Ti multilayered films

In the present work, a high-strength lightweight Al/Ti multilayered film was fabricated using a magnetron sputtering method, and its deformation behaviour was studied under nanoindentation. The Al and Ti layers were approximately 70 and 50 nm, respectively, in thickness, with the total film thickness of 2.4 mu m. According to the measured hardness, the specific strength of the Al/Ti multilayer film was estimated at 245 kN m/kg, higher than most reported nanostructured metallic multilayer films. After nanoindentation, the deformation behaviour of each layer was examined in detail using SEM-FIB. It shows that the two materials exhibited co-deformation behaviour when the layers were thinned to approximately 30 nm. It was also found that the co-deformation behaviour of the Al/Ti multilayers resulted in cooperative-layer-induced shear bands under nanoindentation. Further, nanoscratch-induced deformation behaviour of the Al/Ti multilayers, such as layer buckling, was investigated.