Thermal dissolution mechanisms of AlN/CrN hard coating superlattices studied by atom probe tomography and transmission electron microscopy. (15th February 2015)

• Record Type: Journal Article
• Authors: Tytko, Darius; Choi, Pyuck-Pa; Raabe, Dierk
• Is Part Of: Acta materialia. Volume 85(2015)
• Page Start: 32
• Page End: 41
• Publication Date: 2015-02-15
• Subjects: AlN/CrN -- Hard coatings -- Thermal stability -- Layer pinch-off -- Atom probe tomography; Materials -- Periodicals; Materials science -- Periodicals; Materials -- Mechanical properties -- Periodicals; Metallurgy -- Periodicals; Chemistry, Inorganic -- Periodicals; 620.112
• DOI: 10.1016/j.actamat.2014.11.004
• Languages: English
• ISSNs: 1359-6454

Abstract

Abstract: AlN/CrN superlattices with a B1 cubic crystal structure and a bilayer period of 4 nm were deposited by reactive radiofrequency magnetron sputtering. The coatings were investigated with respect to their thermal stability and changes in microstructure and chemical composition at 900 °C. The AlN layers show high chemical stability but undergo dissolution by pinching off at grain boundaries. A transformation from cubic to hexagonal AlN with subsequent coarsening at grain boundary triple junctions is observed. In contrast to AlN, the CrN layers show poor chemical stability and their compositions are shifted towards Cr2 N upon annealing in a protective argon atmosphere due to nitrogen loss. However, even after establishing Cr2 N stoichiometry the crystal structure of the layers remains cubic.