Tetragonal distortion in magnetron sputtered bcc-W films with supersaturated carbon

Autor: B.O. Mukhamedov, S. Fritze, M. Ottosson, B. Osinger, E. Lewin, B. Alling, U. Jansson, I.A. Abrikosov
Jazyk: angličtina
Rok vydání: 2022
Předmět:
Zdroj: Materials & Design, Vol 214, Iss , Pp 110422- (2022)
Druh dokumentu: article
ISSN: 0264-1275
DOI: 10.1016/j.matdes.2022.110422
Popis: Carbon has a low solid solubility in bcc tungsten at equilibrium. However, metastable supersaturated solid solutions can be synthesized with magnetron sputtering. Here, we present a systematic study on the phase stability and mechanical properties of such supersaturated W–C solid solutions. Θ–2θ scans show a split of the 200/020 and the 002 peaks for supersaturated films which is explained by a tetragonal distortion of the bcc structure. This split increases with increasing C content and is maximized at 4 at.% C, where we observe an a/b axis of 3.15–3.16 Å and a c-axis of 3.21–3.22 Å. We performed first-principles calculations of lattice parameters, mixing enthalpies, elastic constants and polycrystalline elastic moduli for cubic and tetragonal W–C solid solutions. Calculations show that tetragonal structure is more stable than the bcc supersaturated solid solution and the calculated lattice parameters and Young’s moduli follow the same trends as the experimental ones as a function of C concentration. The results suggest that supersaturated films with lattice distortion can be used as a design approach to improve the properties of transition metal films with a bcc structure.
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