Self-organized anisotropic (Zr1−xSix)Ny nanocomposites grown by reactive sputter deposition.

The physical properties of hard and superhard nanocomposite thin films are strongly dependent on their nanostructure. Here, we present the results of an investigation of nanostructural evolution and the resulting mechanical properties of (Zr 1− x Si x )N y films, with 0 ⩽ x ⩽ 1 and 1 ⩽ y ⩽ 1.27, grown on MgO(0 0 1) and Al 2 O 3 (0 0 0 1) substrates at temperatures T s = 500–900 °C by reactive magnetron sputter deposition from Zr and Si targets. X-ray diffraction and transmission electron microscopy (TEM) results show that there is a T s /composition window in which stoichiometric Zr–Si–N and amorphous a-Si 3 N 4 phases mutually segregate and self-organize into encapsulated 3–5 nm wide ZrN-rich (Zr 1− x Si x )N columns which extend along the growth direction with a strong (0 0 2) texture. Lattice-resolved scanning TEM and energy-dispersive X-ray spectroscopy reveal that the (Zr 1− x Si x )N y nanocolumns are separated by a bilayer tissue phase consisting of a thin crystalline SiN y -rich (Zr 1− x Si x )N y layer with an a-Si 3 N 4 overlayer. Incorporation of metastable SiN into NaCl-structure ZrN leads to an enhanced nanoindentation hardness H which is a function of T s and film composition. For nanocomposites with composition (Zr 0.8 Si 0.2 )N 1.14 (10 at.% Si) H, increases from 26 GPa at 500 °C to 37 GPa at 900 °C. For comparison, the hardness of epitaxial ZrN/MgO(0 0 1) layers grown at T s = 800 °C is 24 GPa. [ABSTRACT FROM AUTHOR]