Melting Point of Pure Cr and Phase Equilibria in the Cr-Si Binary System

Ioroi, Kazushige; Aono, Yuki; Xu, Xiao; Omori, Toshihiro; Kainuma, Ryosuke

doi:10.1007/s11669-022-00954-9

Cited by 5 publications

(1 citation statement)

References 33 publications

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“…The purpose of preparing this layer of Cr film was to prevent the VG from growing on the substrate area covered by the Cr. In addition, metal Cr with a high melting point (about 1907 °C [ 20 ]) was chosen to ensure the integrity and regularity of the pattern, since it would not melt or agglomerate during the synthesis of VG. The synthesis of VG can be performed indiscriminately on the surfaces of the Cr and the exposed SiO 2 .…”

Section: Resultsmentioning

confidence: 99%

Direct Growth of Patterned Vertical Graphene Using Thermal Stress Mismatch between Barrier Layer and Substrate

Qian

Deng

et al. 2023

Nanomaterials

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Vertical graphene (VG) combines the excellent properties of conventional graphene with a unique vertical nanosheet structure, and has shown tremendous promise in the field of electronics and composites. However, its complex surface morphology brings great difficulties to micro-nano fabrication, especially regarding photolithography induced nanosheet collapse and remaining chemical residues. Here, we demonstrate an innovative method for directly growing patterned VG on a SiO2/Si substrate. A patterned Cr film was deposited on the substrate as a barrier layer. The VG was synthesized by PECVD on both the patterned Cr film and the exposed SiO2/Si substrate. During the cooling process, the patterned Cr film covered by VG naturally peeled off from the substrate due to the thermal stress mismatch, while the VG directly grown on the SiO2/Si substrate was remained. The temperature-dependent thermal stress distribution in each layer was analyzed using finite element simulations, and the separation mechanism of the Cr film from the substrate was explained. This method avoids the contamination and damage caused by the VG photolithography process. Our work is expected to provide a convenient and reliable solution for the manufacture of VG-based electronic devices.

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Section: Resultsmentioning

confidence: 99%

Direct Growth of Patterned Vertical Graphene Using Thermal Stress Mismatch between Barrier Layer and Substrate

Qian

Deng

et al. 2023

Nanomaterials

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Strength of Disordered and Ordered Al‐Containing Refractory High‐Entropy Alloys

Laube,

Winkens,

Kauffmann

et al. 2024

Adv Eng Mater

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Body‐centered cubic refractory high entropy alloys (RHEA) are promising for high‐temperature structural application due to their exceptional properties, particularly in terms of yield strength at elevated temperatures. For certain alloy systems, such as Mo‐Ti‐Cr‐Al, both disordered (A2) and ordered (B2) crystal structures are possible. In this particular system, a solid‐state transformation from A2 to B2 during cooling occurs. For Al concentrations above approximately 10 at.%, B2 order is obtained from the transformation temperature down to room temperature, while A2 is stable above room temperature below the critical Al content. In this study, two alloys from the Mo‐Ti‐Cr‐Al system close to the transition between A2 and B2 were investigated. Nanoindentation tests revealed that the magnitude of strain rate sensitivity for both alloys is small compared to classical alloys, however, significantly temperature dependent up to the strength plateau temperatures. The yield strength plateau, which is insensitive to the strain rate, was observed at temperatures exceeding 573 K. Modelling of solid solution strengthening reproduces the experimental data in the Al‐lean A2 alloys. However, the observed discontinuous increase of strength in the Al‐rich B2 alloys can only be rationalized by the appearance of B2 order and to no significant other obvious strengthening mechanisms.This article is protected by copyright. All rights reserved.

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The Influence of Mo Content and Annealing on the Oxidation Behavior of Arc‐Melted Cr–xMo–8Si Alloys

Koliotassis,

White,

Galetz

2024

Adv Eng Mater

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The influence of Mo (10‐40at.%) additions to Cr‐8at.%Si was systematically studied by producing arc melted alloys and analyzing the as‐cast and annealed microstructures as well as the oxidation resistances. The majority of the alloys contained a solid solution A2 matrix with the intermetallic A15 = (Cr,Mo)3Si phase. The oxidation resistance was tested by thermogravimetric analysis (TGA) at 1200 °C in air for 50 and 100 h. Samples were characterized by XRD, SEM and EPMA (WDS). The studied Cr‐xMo‐8Si alloy series showed a beneficial effect of Mo on the corrosion behavior of the annealed arc melted alloys exposed at 1200 °C in air. An increased amount of A15 led to the formation of a continuous SiO2 scale beneath the Cr2O3 layer during high temperature exposure. The internal SiO2 layer inhibited further internal oxidation of the A15 phase. Prior annealing also influenced the oxidation behavior of the alloys. Higher annealing temperatures, resulted in an overall reduced fraction of the A15 phase, as well as coarsening, but also showed a more uniform size and distribution of the precipitates, which seems to benefit the formation of a protective duplex oxide scale. Cr‐25Mo‐8at.%Si annealed at 1350 °C for 100 h, showed the most promising oxidation behavior after exposure in air at 1200 °C for 100 h. For all of the investigated Mo contents, no nitridation was observed when compared to the Cr‐8Si reference composition. The oxide scale adhesion also was improved. For Mo >25 at.% no spallation was observed. Evaluation of the TGA data showed it follows the paralinear law, with both the growth rate, kp, and volatilization rate, kv, of Cr2O3 being reduced by adding 10‐25 at.% Mo. A binary Cr/Mo‐Si phase diagram was generated for the studied alloy series in order to determine accurate annealing conditions and estimate the stability range of the metastable σ phase.This article is protected by copyright. All rights reserved.

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Melting Point of Pure Cr and Phase Equilibria in the Cr-Si Binary System

Cited by 5 publications

References 33 publications

Direct Growth of Patterned Vertical Graphene Using Thermal Stress Mismatch between Barrier Layer and Substrate

Direct Growth of Patterned Vertical Graphene Using Thermal Stress Mismatch between Barrier Layer and Substrate

Strength of Disordered and Ordered Al‐Containing Refractory High‐Entropy Alloys

The Influence of Mo Content and Annealing on the Oxidation Behavior of Arc‐Melted Cr–xMo–8Si Alloys

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