Amorphous phase stability of NbTiAlSiN X high-entropy films

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High-entropy amorphous NbTiAlSiW x N y films (x = 0 or 1, i.e., NbTiAlSiN y and NbTiAlSiWN y ) were prepared by magnetron sputtering method in the atmosphere of a mixture of N 2 + Ar (N 2 + Ar = 24 standard cubic centimeter per minute (sccm)), where N 2 = 0, 4, and 8 sccm). All the as-deposited films present amorphous structures, which remain stable at 700˝C for over 24 h. After heat treatment at 1000˝C the films began to crystalize, and while the NbTiAlSiN y films (N 2 = 4, 8 sccm) exhibit a face-centered cubic (FCC) structure, the NbTiAlSiW metallic films show a body-centered cubic (BCC) structure and then transit into a FCC structure composed of nanoscaled particles with increasing nitrogen flow rate. The hardness and modulus of the as-deposited NbTiAlSiN y films reach maximum values of 20.5 GPa and 206.8 GPa, respectively. For the as-deposited NbTiAlSiWN y films, both modulus and hardness increased to maximum values of 13.6 GPa and 154.4 GPa, respectively, and then decrease as the N 2 flow rate is increased. Both films could be potential candidates for protective coatings at high temperature.

Section: Chemical Compositionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nano-Crystallization of High-Entropy Amorphous NbTiAlSiWxNy Films Prepared by Magnetron Sputtering

Sheng

Yang

Wang

et al. 2016

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“…The Al x FeCrCoNiCu HEA coating prepared on a steel substrate by magnetron sputtering has good anti-corrosive properties [31]. Sheng et al [32] used direct-current (DC) bias magnetron sputtering amorphous NbTiAlSiNx films with high hardness and modulus. The microstructures of the films are amorphous, and the microstructures are transformed into crystal structures at temperatures above 1000 • C. Sheng et al [23] reported that amorphous NbTiAlSiW x N y HEA films have high hardness and modulus, and are thermally stabile up to 700 • C, whereas the films transformed into crystal structures at temperatures greater than 1000 • C. Xing et al [33] reported that NbTiAlSiZrN x HEA films sputtered by direct current power had good thermal stability at 600 • C. The Cr 6 Fe 6 V 6 Ta 42 W 40 multicomponent alloy film exhibited great solar absorption at room temperature [34].…”

Section: Introductionmentioning

confidence: 99%

“…TiAlN and ZrN films have been widely used as protective coating. The NbTiAlSi system HEA films have been reported to possess high hardness and modulus [23,32,33]. CoCrFeNiAl 0.3 films fabricated by RF sputtering demonstrate better corrosion resistance than in 3.5 wt.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Corrosion Resistance of NbTiAlSiZrNx High-Entropy Films Prepared by RF Magnetron Sputtering

Xing

Wang

Chen

et al. 2019

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In this study, we designed and fabricated NbTiAlSiZrNx high-entropy alloy (HEA) films. The parameters of the radio frequency (RF) pulse magnetron sputtering process were fixed to maintain the N2 flux ratio at 0%, 10%, 20%, 30%, 40%, and 50%. Subsequently, NbTiAlSiZrNx HEA films were deposited on the 304 stainless steel (SS) substrate. With an increasing N2 flow rate, the film deposited at a RN of 50% had the highest hardness (12.4 GPa), the highest modulus (169 GPa), a small roughness, and a beautiful color. The thicknesses of the films were gradually reduced from 298.8 nm to 200 nm, and all the thin films were of amorphous structure. The electrochemical corrosion resistance of the film in a 0.5 mol/L H2SO4 solution at room temperature was studied and the characteristics changed. The HEA films prepared at N2 flow rates of 10% and 30% were more prone to corrosion than 304 SS, but the corrosion rate was lower than that of 304 SS. NbTiAlSiZrNx HEA films prepared at N2 flow rates of 20%, 40%, and 50% were more corrosion-resistant than 304 SS. In addition, the passivation stability of the NbTiAlSiZrNx HEA was worse than that of 304 SS. Altogether, these results show that pitting corrosion occurred on NbTiAlSiZrNx HEA films.

“…Based on a similar scientific concept, HEFs have been designed and investigated gradually and show a great potential for application in the coating industry [ 7 , 8 , 9 , 10 , 11 , 12 ]. To date, many excellent properties of HEFs have been discovered and studied, such as high-wear resistance [ 13 , 14 ], high-corrosion resistance [ 15 , 16 , 17 ], diffusion-barriers effects [ 18 , 19 , 20 ], solar-thermal-conversion effects [ 10 , 21 ], plastic-deformation characteristics [ 22 , 23 ], thermal stabilities [ 7 , 24 , 25 ], and soft magnetic properties [ 26 ]. However, there are few theories that can explain the mechanism of the phase formation of the HEFs.…”

Section: Introductionmentioning

confidence: 99%

Effects of Nitrogen Content on the Structure and Mechanical Properties of (Al0.5CrFeNiTi0.25)Nx High-Entropy Films by Reactive Sputtering

Zhang

Yan

Liao

et al. 2018

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In this study, (Al0.5CrFeNiTi0.25)Nx high-entropy films are prepared by a reactive direct current (DC) magnetron sputtering at different N2 flow rates on silicon wafers. It is found that the structure of (Al0.5CrFeNiTi0.25)Nx high-entropy films is amorphous, with x = 0. It transforms from amorphous to a face-centered-cubic (FCC) structure with the increase of nitrogen content, while the bulk Al0.5CrFeNiTi0.25 counterpart prepared by casting features a body-centered-cubic (BCC) phase structure. The phase formation can be explained by the atomic size difference (δ). Lacking nitrogen, δ is approximately 6.4% for the five metal elements, which is relatively large and might form a BCC or ordered-BCC structure, while the metallic elements in this alloy system all have a trend to form nitrides like TiN, CrN, AlN, and FeN. Therefore, nitride components are becoming very similar in size and structure and solve each other easily, thus, an FCC (Al-Cr-Fe-Ni-Ti)N solid solution forms. The calculated value of δ is approximately 23% for this multicomponent nitride solid solution. The (Al0.5CrFeNiTi0.25)Nx films achieve a pronounced hardness and a Young’s modulus of 21.45 GPa and 253.8 GPa, respectively, which is obviously much higher than that of the as-cast Al0.5CrFeNiTi0.25 bulk alloys.