Microstructure and Mechanical Properties of Rexnbmotaw Thin Films Prepared By RF Magnetron Sputtering

Abstract

High Entropy Alloys (HEAs) and Refractory High-Entropy Alloys (RHEAs) are novel potential materials for high-temperature applications [1]. NbMoTaW, a RHEAs, such as the one in Fig. 1, possess superior mechanical properties, combining high strength, outstanding thermal stability, and resistance to softening at high temperatures [2]. The influence of adding Vanadium [3], Tantalum [4], and Rhenium [5] to NbMoTaW alloys on the bulk mechanical behavior was investigated by the previous studies. In this research, the effect of adding Rhenium with different (Re0, Re0.5, Re1) on the microstructure and the mechanical properties of NbMoTaW thin films will be nvestigated. The larger the enthalpy of mixing in negative values, the higher the binding force between the elements, which has been enhanced with Rhenium addition. As for the entropy of mixing, it increased from 11.53 to 13.38 for Re0 and Re1, respectively. The higher the mixture entropy suggests a more stable solid solution. This is confirmed by calculating the thermodynamic parameters proposed by Yang et. Al [6] where they suggested that a mixture with δ < 6.6 and Ω > 1.1 correspond to solid solution formation. The anticipated crystal structure for the three samples is BCC structure according to the valence electron concentration (VEC) theory, where the VEC values were less than 6.87 as suggested by Gou et. Al [7]. The RexNbMoTaW HEAs thin films are fabricated using RF magnetron sputtering. The film thickness, deposition power, and temperature impact on the films’ characteristics are studied. Field emission (FE-SEM), X-ray diffraction (XRD), and nanoindentation are used to investigate the RexNbMoTaW thin films’ crystal structure, surface morphology, and mechanical properties. The mechanical properties of the thin films will be compared with their counterpart bulk materials. References Kim, H., et al., International Journal of Refractory Metals and Hard Materials, 2019. 80: p. 286-291. Feng, X., et al., Materials Letters, 2018. 210: p. 84-87. Senkov, O.N., et al., Intermetallics, 2011. 19(5): p. 698-706. Han, Z.D., et al., Materials Science and Engineering: A, 2018. 712: p. 380-385. Zhang, J., et al., Journal of Alloys and Compounds, 2020. 827. Yang, X. and Y. Zhang, Materials Chemistry and Physics, 2012. 132(2-3): p. 233-238. Guo, S., et al., Journal of Applied Physics, 2011. 109(10): p. 103505. Figure 1