Al80Cr20N-layer thickness-dependent microstructure and mechanical properties of Al50Cr50N/Al80Cr20N nanomultilayered films

Abstract

New Al50Cr50N/Al80Cr20N nanomultilayered films with different Al80Cr20N layer thicknesses were synthesized by reactive magnetron sputtering. The effect of the thickness of the Al80Cr20N layer on the microstructure and mechanical properties of the Al50Cr50N/Al80Cr20N nanomultilayered films was investigated by X-ray diffraction, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and nanoindentation techniques. The results indicated that when the Al80Cr20N layer thickness was less than 0.9 nm, the Al80Cr20N layers were forced to transform to the face-centered cubic structure under the template effect of the Al50Cr50N layers and grew epitaxially with the Al50Cr50N layers, while the average crystallite size decreased. For the nanomultilayered film with the Al80Cr20N layer thickness of 0.9 nm, the maximum hardness and elastic modulus reached 39.2 GPa and 356.4 GPa, respectively. As the thickness of the Al80Cr20N layer increased from 0.9 nm to 1.35 nm, the average crystallite size increased, and the epitaxial growth between the Al50Cr50N and Al80Cr20N layers was terminated, resulting in the decrease of elastic modulus and hardness. In addition, the strengthening effect of the Al50Cr50N/Al80Cr20N nanomultilayered film was discussed.