Thermal stability of TiAlN/CrN multilayer coatings studied by atom probe tomography

Pyuck-Pa Choi; Ivan Povstugar; Jae-Pyeong Ahn; Aleksander Kostka; Dierk Raabe

doi:10.1016/j.ultramic.2010.11.012

Thermal stability of TiAlN/CrN multilayer coatings studied by atom probe tomography

Ultramicroscopy. 2011 May;111(6):518-23. doi: 10.1016/j.ultramic.2010.11.012. Epub 2010 Nov 19.

Authors

Pyuck-Pa Choi¹, Ivan Povstugar, Jae-Pyeong Ahn, Aleksander Kostka, Dierk Raabe

Affiliation

¹ Max-Planck-Institut für Eisenforschung, Department for Microstructure Physics and Metal Forming, Max-Planck-Strasse 1, 40237 Düsseldorf, Germany.

PMID: 21146308
DOI: 10.1016/j.ultramic.2010.11.012

Abstract

This study is about the microstructural evolution of TiAlN/CrN multilayers (with a Ti:Al ratio of 0.75:0.25 and average bilayer period of 9 nm) upon thermal treatment. Pulsed laser atom probe analyses were performed in conjunction with transmission electron microscopy and X-ray diffraction. The layers are found to be thermally stable up to 600 °C. At 700 °C TiAlN layers begin to decompose into Ti- and Al-rich nitride layers in the out-of-plane direction. Further increase in temperature to 1000 °C leads to a strong decomposition of the multilayer structure as well as grain coarsening. Layer dissolution and grain coarsening appear to begin at the surface. Domains of AlN and TiCrN larger than 100 nm are found, together with smaller nano-sized AlN precipitates within the TiCrN matrix. Fe and V impurities are detected in the multilayers as well, which diffuse from the steel substrate into the coating along columnar grain boundaries.