Self-organized nanostructuring in Zr0.69Al0.31N thin films studied by atom probe tomography

• Atom probe tomography of sputtered self-organized nanostructured Zr(Al)N/Al(Zr)N thin films.
• APT observations show thin Al-rich plates between thicker Al-deficient ones; Zr and N maps lack such features.
• It is shown that steady state growth originates about 5–8 nm above the substrate.
• The phase purity of self-organized lamellas is determined.
• Breakdown of nanolabyrinthine growth by ZrN precipitation is observed.

We have applied atom probe tomography (APT) to analyze self-organizing structures of wear-resistant Zr0.69Al0.31N thin films grown by magnetron sputtering. Transmission electron microscopy shows that these films grow as a three-dimensional nanocomposite, consisting of interleaved lamellae in a labyrinthine structure, with an in-plane size scale of ~ 5 nm. The structure was recovered in the Al APT signal, while the Zr and N data lacked structural information. The onset of the self-organized labyrinthine growth was observed to occur by surface nucleation, 5–8 nm above the MgO substrate, due to increasing Zr–Al compositional fluctuations during elemental segregation. At a final stage, the labyrinthine growth mode was observed to be interrupted by the formation of larger ZrN grains.