High temperature decomposition and age hardening of single-phase wurtzite Ti_1-xAl_xN thin films grown by cathodic arc deposition

2023/05/30 by Salamania, J., Bock, F., Johnson, L. J. S. +6
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Other Condensed Matter (cond-mat.other)

paper · doi:10.48550/arxiv.2305.18950

Abstract

We investigated the high temperature decomposition behavior of wurtzite phase Ti_1-xAl_xN films using experimental methods and first-principles calculations. Single phase metastable wurtzite Ti_1-xAl_xN (x = 0.65, 0.75, 085 and 0.95) solid solution films were grown by cathodic arc deposition using low duty cycle pulsed substrate-bias voltage. First-principles calculated elastic constants of the wurtzite Ti_1-xAl_xN phase show a strong dependence on alloy composition. The predicted phase diagram shows a miscibility gap with an unstable region. High resolution scanning transmission electron microscopy and chemical mapping demonstrate decomposition of the films after high temperature annealing (950^∘C), which resulted in nanoscale chemical compositional modulations containing Ti-rich and Al-rich regions with coherent or semi coherent interfaces. This spinodal decomposition of the wurtzite film causes age hardening of 1-2 GPa.

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