Predicting high temperature mechanical properties of CrN and CrAlN coatings from in-situ synchrotron radiation X-ray diffraction

• We investigated the phase composition of CrN and CrAlN coatings by in-situ high SR-XRD.
• At the high temperature, a Cr2N phase was observed in the CrN coating.
• SR-XRD measurements elucidate predictions of the crystallite size and strain of the main phases.
• Observation showed that CrN is the major phase in Al and Cr coatings.

This contribution investigates the phase composition of CrN and CrAlN coatings by in-situ high temperature synchrotron radiation (SR-XRD), with the coatings deposited on steel substrate by closed field unbalance magnetron sputtering. Rietveld refinement on the SR-XRD spectra indicated CrN as the major phase, over the temperature range of 25 °C – 700 °C, for both coatings. At the high temperature of 700 °C, a Cr2N phase was observed in the CrN coating while the CrAlN coating also had a Cr phase. Williamson–Hall plots, from the refined data, afforded estimating variations of the strain and crystallite size of the major phase, up to 700 °C. The crystallite size (10 nm) for the CrAlN coating, at 25 °C, agrees very well with previous GI-XRD and TEM results obtained at room temperature Li et al. (2012).