High temperature decomposition and age hardening of single-phase wurtzite Ti$_{1-x}$Al$_{x}$N thin films grown by cathodic arc deposition

J. Salamania; F. Bock; L. J. S. Johnson; F. Tasnádi; K. M. Calamba Kwick; A. F. Farhadizaeh; I. A. Abrikosov; L. Rogström; M. Odén

arXiv · 2305.18950

High temperature decomposition and age hardening of single-phase wurtzite Ti$_{1-x}$Al$_{x}$N thin films grown by cathodic arc deposition

J. Salamania·F. Bock·L. J. S. Johnson·F. Tasnádi·K. M. Calamba Kwick·A. F. Farhadizaeh·I. A. Abrikosov·L. Rogström·M. Odén

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Abstract

We investigated the high temperature decomposition behavior of wurtzite phase Ti$_{1-x}$Al$_{x}$N films using experimental methods and first-principles calculations. Single phase metastable wurtzite Ti$_{1-x}$Al$_{x}$N (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$_{1-x}$Al$_{x}$N 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$^{\circ}$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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J. Salamania, F. Bock, L. J. S. Johnson, F. Tasnádi, K. M. Calamba Kwick, A. F. Farhadizaeh, I. A. Abrikosov, L. Rogström, M. Odén. 2023-05-30. High temperature decomposition and age hardening of single-phase wurtzite Ti$_{1-x}$Al$_{x}$N thin films grown by cathodic arc deposition. https://arxiv.org/abs/2305.18950

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