Informace o publikaci

Influence of ion irradiation-induced defects on phase formation and thermal stability of Ti0.27Al0.21 N (0.52) coatings

Autoři	HOLZAPFEL Damian M MUSIC Denis MRAZ Stanislav AGHDA Soheil Karimi ETTER Martin ONDRAČKA Pavel HANS Marcus BOGDANOVSKI Dimitri EVERTZ Simon PATTERER Lena SCHMIDT Paul SCHOKEL Alexander ERIKSSON Anders O ARNDT Mirjam PRIMETZHOFER Daniel SCHNEIDER Jochen M
Rok publikování	2022
Druh	Článek v odborném periodiku
Časopis / Zdroj	Acta Materialia
Citace
Doi	http://dx.doi.org/10.1016/j.actamat.2022.118160
Klíčová slova	Frenkel pairs; thermal stability; TiAlN; Hard coatings; Cathodic arc evaporation
Popis	The influence of changes induced by ion irradiation on structure and thermal stability of metastable cu-bic (Ti,Al)N coatings deposited by cathodic arc evaporation is systematically investigated by correlating experiments and theory. Decreasing the nitrogen deposition pressure from 5.0 to 0.5 Pa results in an ion flux-enhancement by a factor of three and an increase of the average ion energy from 15 to 30 eV, caus-ing the stress-free lattice parameter to expand from 4.170 to 4.206 A, while the chemical composition of Ti0.27Al0.21N0.52 remains unchanged. The 0.9% lattice parameter increase is a consequence of formation of Frenkel pairs induced by ion bombardment, as revealed by density functional theory (DFT) simulations. The influence of the presence of Frenkel pairs on the thermal stability of metastable Ti0.27Al0.21N0.52 is investigated by scanning transmission electron microscopy, differential scanning calorimetry, atom probe tomography and in-situ synchrotron X-ray powder diffraction. It is demonstrated that the ion flux and ion energy induced formation of Frenkel pairs increases the thermal stability as the Al diffusion enabled crystallization of the wurtzite solid solution is retarded. This can be rationalized by DFT predictions since the presence of Frenkel pairs increases the activation energy for Al diffusion by up to 142%. Hence, the thermal stability enhancement is caused by a hitherto unreported mechanism -the Frenkel pair impeded Al mobility and thereby retarded formation of wurtzite solid solution. (C) 2022 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.