High-strength Ni/Al nanolaminates fabricated by magnetron sputtering and their nanoindentation and nanowear behaviors

Abstract

Here we report on the fabrication of face-centered cubic/face-centered cubic (fcc/fcc) crystal-structured high-strength nickel (Ni)/aluminum (Al) nanolaminates with individual layer thicknesses of 10 and 50 nm using magnetron sputtering on a silicon (Si) substrate. Soft and lightweight Al is introduced as a constituent material into Ni/Al nanolaminates in order to develop lightweight and high-strength metallic nanolaminates. The microstructures of the nanolaminates have been characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Their mechanical properties and their nanowear behaviors have been studied by nanoindentation and nanowear tests, respectively. Our results show that the individual layer thickness affected the strength and the nanowear behavior of the nanolaminates. The nanohardness and reduced elastic modulus increased from ∼3.36 GPa and ∼78.30 GPa for the nanolaminate with 50 nm individual layers to ∼5.07 GPa and ∼130.52 GPa for the nanolaminate with 10 nm individual layers, respectively. The wear rate of the nanolaminates increased with an increase in the applied loads, but decreased with a decrease in individual layer thickness from 50 nm to 10 nm with different applied loads. The existence of nanotwinned structures in the high stacking fault energy (SFE) Ni and Al layers may have contributed to the enhanced strength of these Ni/Al nanolaminates.